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Pathology is the study of the causes and effects of
disease A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medica ...
or
injury An injury is any physiological damage to living tissue caused by immediate physical stress. An injury can occur intentionally or Accident, unintentionally and may be caused by blunt trauma, penetrating trauma, burning, Toxin, toxic exposure, asp ...
. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of Cell (biology), cells that proce ...
research fields and medical practices. However, when used in the context of modern medical treatment, the term is often used in a narrower fashion to refer to processes and tests that fall within the contemporary medical field of "general pathology", an area which includes a number of distinct but inter-related
medical specialties A medical specialty is a branch of medical practice that is focused on a defined group of patients, diseases, skills, or philosophy. Examples include those branches of medicine that deal exclusively with children (pediatrics, paediatrics), cancer ...
that diagnose disease, mostly through analysis of tissue,
cell Cell most often refers to: * Cell (biology) The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a Cell membrane, membrane, and contains many biomolecules such as proteins, D ...
, and
body fluid Body fluids, bodily fluids, or biofluids, sometimes body liquids, are liquids within the human body. In lean healthy adult men, the total body water is about 60% (60–67%) of the total Human body weight, body weight; it is usually slightly lower ...
samples. Idiomatically, "a pathology" may also refer to the predicted or actual progression of particular diseases (as in the statement "the many different forms of
cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Poss ...
have diverse pathologies", in which case a more proper choice of word would be " pathophysiologies"), and the
affix In linguistics Linguistics is the scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, objective, and precise analysis of all aspects of language, particularly its nature and ...
''pathy'' is sometimes used to indicate a state of disease in cases of both physical ailment (as in
cardiomyopathy Cardiomyopathy is a group of diseases that affect the heart muscle. Early on there may be few or no symptoms. As the disease worsens, dyspnea, shortness of breath, feeling fatigue (medical), tired, and pedal edema, swelling of the legs may occu ...
) and
psychological Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between ...
conditions (such as
psychopathy Psychopathy, sometimes considered synonymous with sociopathy, is characterized by persistent antisocial behavior, impaired empathy Empathy is the capacity to understand or feel what another person is experiencing from within their fram ...
). A
physician A physician (American English), medical practitioner (English in the Commonwealth of Nations, Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, mai ...
practicing pathology is called a ''pathologist''. As a field of general inquiry and research, pathology addresses components of disease: cause, mechanisms of development (
pathogenesis Pathogenesis is the process by which a disease or Disease#Disorder, disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes from Anci ...
), structural alterations of cells (morphologic changes), and the consequences of changes (clinical manifestations). In common medical practice, general pathology is mostly concerned with analyzing known clinical abnormalities that are markers or precursors for both
infectious An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmiss ...
and non-infectious disease, and is conducted by experts in one of two major specialties,
anatomical pathology Anatomical pathology (''Commonwealth'') or Anatomic pathology (''U.S.'') is a medical specialty that is concerned with the diagnosis of disease based on the macroscopic, microscopic, biochemical, immunologic and molecular examinatio ...
and
clinical pathology Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the Medical laboratory, laboratory analysis of bodily fluids, such as blood, urine, and tissue homogenates or extracts using the tools of clinic ...
. Further divisions in specialty exist on the basis of the involved sample types (comparing, for example,
cytopathology Cytopathology (from Ancient Greek, Greek , ''kytos'', "a hollow"; , ''pathos'', "fate, harm"; and , ''-logy, -logia'') is a branch of pathology that studies and diagnoses diseases on the cellular level. The discipline was founded by George Nico ...
,
hematopathology Hematopathology or hemopathology (both also spelled haem-, see American_and_British_English_spelling_differences#ae_and_oe, spelling differences) is the study of diseases and disorders affecting and found in blood cells, their production, and any ...
, and
histopathology Histopathology (compound of three Greek language, Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία ''-logy, -logia'' "study of") refers to the light microscope, microscopic examination of Tissue (biology), ti ...
), organs (as in
renal pathology The kidneys are two reddish-brown bean-shaped organs In biology, an organ is a collection of Tissue (biology), tissues joined in a structural unit to serve a common function. In the biological organization, hierarchy of life, an organ lies ...
), and physiological systems (
oral pathology Oral and maxillofacial pathology refers to the diseases of the mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also ...
), as well as on the basis of the focus of the examination (as with
forensic pathology Forensic pathology is pathology that focuses on determining the cause of death by examining a corpse. A post mortem examination is performed by a medical examiner or forensic pathologist, usually during the investigation of criminal law cases an ...
). Pathology is a significant field in modern
medical diagnosis Medical diagnosis (abbreviated Dx, Dx, or Ds) is the process of determining which disease or condition explains a person's symptoms and medical sign, signs. It is most often referred to as diagnosis with the medicine, medical context being implic ...
and
medical research Medical research (or biomedical research), also known as experimental medicine, encompasses a wide array of research, extending from " basic research" (also called ''bench science'' or ''bench research''), – involving fundamental scienti ...
.


History

The study of pathology, including the detailed examination of the body, including dissection and inquiry into specific maladies, dates back to antiquity. Rudimentary understanding of many conditions was present in most early societies and is attested to in the records of the earliest
historical societies This is a partial List of Historical society, historical and heritage societies from around the world. The sections provided are not mutually exclusive. Many historical societies websites are their museums' websites. List is organized by location a ...
, including those of the
Middle East The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabian Peninsula, Arabia (including the Arabian Peninsula and Bahrain), Anatolia, Asia Minor (Asian part of Turkey except Hatay Pro ...
,
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
, and
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
. By the
Hellenic period In Classical antiquity Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the in ...
of
ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
, a concerted causal study of disease was underway (see Medicine in ancient Greece), with many notable early physicians (such as
Hippocrates Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the Classical Greece, classical period who is considered one of the most outstanding figures ...
, for whom the modern
Hippocratic Oath The Hippocratic Oath is an oath of ethics historically taken by physicians. It is one of the most widely known of Greek medical texts. In its original form, it requires a new physician to swear, by a number of List of health deities, healing god ...
is named) having developed methods of
diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different academic discipline, disciplines, with variations in the use of logic, analytics, and experience, to determine "causality, cause a ...
and
prognosis Prognosis (Ancient Greek, Greek: πρόγνωσις "fore-knowing, foreseeing") is a medicine, medical term for predicting the likely or expected development of a disease, including whether the sign (medicine), signs and symptoms will improve or ...
for a number of diseases. The medical practices of the Romans and those of the Byzantines continued from these Greek roots, but, as with many areas of scientific inquiry, growth in understanding of medicine stagnated some after the
Classical Era Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the interlocking civilizations of ...
, but continued to slowly develop throughout numerous cultures. Notably, many advances were made in the medieval era of Islam (see
Medicine in medieval Islam In the history of medicine, "Islamic medicine" is the Science in the medieval Islamic world, science of medicine developed in the Middle East, and usually written in Arabic language, Arabic, the ''lingua franca'' of Islamic civilization. Islam ...
), during which numerous texts of complex pathologies were developed, also based on the Greek tradition. Even so, growth in complex understanding of disease mostly languished until knowledge and experimentation again began to proliferate in the
Renaissance The Renaissance ( , ) , from , with the same meanings. is a Periodization, period in History of Europe, European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an e ...
, Enlightenment, and
Baroque The Baroque (, ; ) is a Style (visual arts), style of Baroque architecture, architecture, Baroque music, music, Baroque dance, dance, Baroque painting, painting, Baroque sculpture, sculpture, poetry, and other arts that flourished in Europe from ...
eras, following the resurgence of the empirical method at new centers of scholarship. By the 17th century, the study of rudimentary
microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...
was underway and examination of tissues had led
British Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
member
Robert Hooke Robert Hooke Fellow of the Royal Society, FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using ...
to coin the word "
cell Cell most often refers to: * Cell (biology) The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a Cell membrane, membrane, and contains many biomolecules such as proteins, D ...
", setting the stage for later
germ theory The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to be seen without magnification, invade h ...
. Modern pathology began to develop as a distinct field of inquiry during the 19th Century through natural philosophers and physicians that studied disease and the informal study of what they termed "pathological anatomy" or "morbid anatomy". However, pathology as a formal area of specialty was not fully developed until the late 19th and early 20th centuries, with the advent of detailed study of
microbiology Microbiology () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriolog ...
. In the 19th century, physicians had begun to understand that disease-causing pathogens, or "germs" (a catch-all for disease-causing, or pathogenic, microbes, such as
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometre The micrometre (Amer ...
,
viruses A virus is a wikt:submicroscopic, submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and ...
,
fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...
,
amoebae An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism A unicellular organism, also known as a single-celled organism, is an organism ...
, molds,
protist A protist () is any eukaryotic organism (that is, an organism whose Cell (biology), cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a Common descent, common ancestor (the last eukary ...
s, and
prion Prions are Proteinopathy, misfolded proteins that have the ability to transmit their misfolded shape onto normal variants of the same protein. They characterize several fatal and transmissible neurodegenerative diseases in humans and many othe ...
s) existed and were capable of reproduction and multiplication, replacing earlier beliefs in humors or even spiritual agents, that had dominated for much of the previous 1,500 years in European medicine. With the new understanding of causative agents, physicians began to compare the characteristics of one germ's symptoms as they developed within an affected individual to another germ's characteristics and symptoms. This approach led to the foundational understanding that diseases are able to replicate themselves, and that they can have many profound and varied effects on the human host. To determine causes of diseases, medical experts used the most common and widely accepted assumptions or symptoms of their times, a general principal of approach that persists into modern medicine. Modern medicine was particularly advanced by further developments of the microscope to analyze tissues, to which
Rudolf Virchow Rudolf Ludwig Carl Virchow (; or ; 13 October 18215 September 1902) was a Germans, German physician, anthropologist, pathologist, prehistorian, biologist, writer, editor, and politician. He is known as "the father of modern pathology" and as th ...
gave a significant contribution, leading to a slew of research developments. By the late 1920s to early 1930s pathology was deemed a medical specialty. Combined with developments in the understanding of general
physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying the ...
, by the beginning of the 20th century, the study of pathology had begun to split into a number of distinct fields, resulting in the development of a large number of modern specialties within pathology and related disciplines of diagnostic medicine.


Etymology

The terms ''pathology'' comes from the
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek Dark ...
roots of ''pathos'' (), meaning "experience" or "suffering" and ''
-logia ''-logy'' is a suffix In linguistics, a suffix is an affix which is placed after the Stem (linguistics), stem of a word. Common examples are case endings, which indicate the grammatical case of nouns, adjectives, and verb endings, which form t ...
'' (), "study of". The Latin term is of early sixteenth-century origin and became increasingly popularized after the 1530s.


General pathology

The modern practice of pathology is divided into a number of subdisciplines within the discrete but deeply interconnected aims of biological research and
medical practice Medicine is the science and Praxis (process), practice of caring for a patient, managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, and Health promotion ...
.
Biomedical research Medical research (or biomedical research), also known as experimental medicine, encompasses a wide array of research, extending from " basic research" (also called ''bench science'' or ''bench research''), – involving fundamental scienti ...
into disease incorporates the work of a vast variety of life science specialists, whereas, in most parts of the world, to be licensed to practice pathology as a medical specialty, one has to complete
medical school A medical school is a tertiary educational institution, or part of such an institution, that teaches medicine, and awards a professional degree for physicians. Such medical degrees include the Bachelor of Medicine, Bachelor of Surgery (MBBS, MB ...
and secure a license to practice medicine. Structurally, the study of disease is divided into many different fields that study or diagnose markers for disease using methods and technologies particular to specific scales,
organs In biology, an organ is a collection of Tissue (biology), tissues joined in a structural unit to serve a common function. In the biological organization, hierarchy of life, an organ lies between Tissue (biology), tissue and an organ system. Tiss ...
, and tissue types. The information in this section mostly concerns pathology as it regards common medical practice in these systems, but each of these specialties is also the subject of voluminous pathology research as regards the disease pathways of specific pathogens and disorders that affect the tissues of these discrete organs or structures.


Anatomical pathology

Anatomical pathology (''Commonwealth'') or anatomic pathology (''United States'') is a medical specialty that is concerned with the diagnosis of disease based on the gross,
microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens (optics), lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded a ...
, chemical, immunologic and
molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...
examination of organs, tissues, and whole bodies (as in a general examination or an
autopsy An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough Physical examination, examination of a Cadaver, corpse by dissection to determine the cause, mode, and manner o ...
). Anatomical pathology is itself divided into subfields, the main divisions being
surgical pathology Surgical pathology is the most significant and time-consuming area of practice for most anatomical pathology, anatomical pathologists. Surgical pathology involves gross and microscopic examination of surgery, surgical specimens, as well as biop ...
,
cytopathology Cytopathology (from Ancient Greek, Greek , ''kytos'', "a hollow"; , ''pathos'', "fate, harm"; and , ''-logy, -logia'') is a branch of pathology that studies and diagnoses diseases on the cellular level. The discipline was founded by George Nico ...
, and
forensic pathology Forensic pathology is pathology that focuses on determining the cause of death by examining a corpse. A post mortem examination is performed by a medical examiner or forensic pathologist, usually during the investigation of criminal law cases an ...
. Anatomical pathology is one of two main divisions of the medical practice of pathology, the other being clinical pathology, the diagnosis of disease through the
laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which science, scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: ...
analysis of bodily fluids and tissues. Sometimes, pathologists practice both anatomical and clinical pathology, a combination known as general pathology.


Cytopathology

Cytopathology (sometimes referred to as "cytology") is a branch of pathology that studies and diagnoses diseases on the cellular level. It is usually used to aid in the diagnosis of cancer, but also helps in the diagnosis of certain infectious diseases and other inflammatory conditions as well as thyroid lesions, diseases involving sterile body cavities (peritoneal, pleural, and cerebrospinal), and a wide range of other body sites. Cytopathology is generally used on samples of free cells or tissue fragments (in contrast to histopathology, which studies whole tissues) and cytopathologic tests are sometimes called smear tests because the samples may be smeared across a glass microscope slide for subsequent staining and microscopic examination. However, cytology samples may be prepared in other ways, including
cytocentrifugation A cytocentrifuge, sometimes referred to as a cytospin, is a specialized centrifuge A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by rotation around a fixed axis, spinning the f ...
.


Dermatopathology

Dermatopathology is a subspecialty of anatomic pathology that focuses on the skin and the rest of the
integumentary system The integumentary system is the set of organs forming the outermost layer of an animal's body. It comprises the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: ...
as an organ. It is unique, in that there are two paths a physician can take to obtain the specialization. All general pathologists and general dermatologists train in the pathology of the skin, so the term dermatopathologist denotes either of these who has reached a certainly level of accreditation and experience; in the US, either a general pathologist or a
dermatologist Dermatology is the branch of medicine dealing with the skin.''Random House Webster's Unabridged Dictionary.'' Random House, Inc. 2001. Page 537. . It is a speciality with both medical and surgical aspects. A List of dermatologists, dermatologist ...
can undergo a 1 to 2 year fellowship in the field of dermatopathology. The completion of this fellowship allows one to take a subspecialty board examination, and becomes a board certified dermatopathologist. Dermatologists are able to recognize most skin diseases based on their appearances, anatomic distributions, and behavior. Sometimes, however, those criteria do not lead to a conclusive diagnosis, and a
skin biopsy Skin biopsy is a biopsy technique in which a skin lesion is removed to be sent to a pathologist to render a microscopic diagnosis. It is usually done under local anesthetic in a physician's office, and results are often available in 4 to 10 days. ...
is taken to be examined under the microscope using usual histological tests. In some cases, additional specialized testing needs to be performed on biopsies, including
immunofluorescence Immunofluorescence is a technique used for optical microscope, light microscopy with a fluorescence microscope and is used primarily on microbiological samples. This technique uses the specificity of antibodies to their antigen to target fluores ...
,
immunohistochemistry Immunohistochemistry (IHC) is the most common application of immunostaining. It involves the process of selectively identifying antigens (proteins) in cells of a tissue section by exploiting the principle of antibody, antibodies binding specifica ...
,
electron microscopy An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...
,
flow cytometry Flow cytometry (FC) is a technique used to detect and measure physical and chemical characteristics of a population of cells or particles. In this process, a sample containing cells or particles is suspended in a fluid and injected into the fl ...
, and molecular-pathologic analysis. One of the greatest challenges of dermatopathology is its scope. More than 1500 different disorders of the skin exist, including cutaneous eruptions ("
rashes A rash is a change of the human skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cra ...
") and
neoplasms A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
. Therefore, dermatopathologists must maintain a broad base of knowledge in clinical dermatology, and be familiar with several other specialty areas in Medicine.


Forensic pathology

Forensic pathology focuses on determining the cause of death by post-mortem examination of a corpse or partial remains. An autopsy is typically performed by a coroner or medical examiner, often during criminal investigations; in this role,
coroner A coroner is a government or judicial official who is empowered to conduct or order an inquest into Manner of death, the manner or cause of death, and to investigate or confirm the identity of an unknown person who has been found dead within th ...
s and medical examiners are also frequently asked to confirm the identity of a corpse. The requirements for becoming a licensed practitioner of forensic pathology varies from country to country (and even within a given nation) but typically a minimal requirement is a medical doctorate with a specialty in general or anatomical pathology with subsequent study in forensic medicine. The methods forensic scientists use to determine death include examination of tissue specimens to identify the presence or absence of natural disease and other microscopic findings, interpretations of
toxicology Toxicology is a scientific discipline (academia), discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnos ...
on body tissues and fluids to determine the chemical cause of overdoses, poisonings or other cases involving toxic agents, and examinations of
physical trauma An injury is any physiological damage to living tissue caused by immediate physical stress. An injury can occur intentionally or Accident, unintentionally and may be caused by blunt trauma, penetrating trauma, burning, Toxin, toxic exposure, asp ...
. Forensic pathology is a major component in the trans-disciplinary field of
forensic science Forensic science, also known as criminalistics, is the application of science to Criminal law, criminal and Civil law (legal system), civil laws, mainly—on the criminal side—during criminal investigation, as governed by the legal standard ...
.


Histopathology

Histopathology refers to the microscopic examination of various forms of
human tissue In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of Cell (biology), ...
. Specifically, in clinical medicine, histopathology refers to the examination of a biopsy or surgical specimen by a pathologist, after the specimen has been processed and histological sections have been placed onto glass slides. This contrasts with the methods of cytopathology, which uses free cells or tissue fragments. Histopathological examination of tissues starts with
surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...
,
biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves extraction of sampling (medicine), sample Cell (biology), cells or Biologica ...
, or autopsy. The tissue is removed from the body of an organism and then placed in a fixative that stabilizes the tissues to prevent decay. The most common fixative is
formalin Formaldehyde ( , ) (systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclat ...
, although frozen section fixing is also common. To see the tissue under a microscope, the sections are stained with one or more pigments. The aim of staining is to reveal cellular components; counterstains are used to provide contrast. Histochemistry refers to the science of using chemical reactions between laboratory chemicals and components within tissue. The histological slides are then interpreted diagnostically and the resulting pathology report describes the histological findings and the opinion of the pathologist. In the case of cancer, this represents the tissue diagnosis required for most treatment protocols.


Neuropathology

Neuropathology is the study of disease of nervous system tissue, usually in the form of either surgical biopsies or sometimes whole brains in the case of autopsy. Neuropathology is a subspecialty of anatomic pathology,
neurology Neurology (from el, wikt:νεῦρον, νεῦρον (neûron), "string, nerve" and the suffix wikt:-logia, -logia, "study of") is the branch of specialty (medicine), medicine dealing with the diagnosis and treatment of all categories of co ...
, and
neurosurgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the specialty (medicine), medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the Human ...
. In many English-speaking countries, neuropathology is considered a subfield of anatomical pathology. A physician who specializes in neuropathology, usually by completing a fellowship after a residency in anatomical or general pathology, is called a neuropathologist. In day-to-day clinical practice, a neuropathologist is a consultant for other physicians. If a disease of the nervous system is suspected, and the diagnosis cannot be made by less invasive methods, a biopsy of nervous tissue is taken from the brain or spinal cord to aid in diagnosis. Biopsy is usually requested after a mass is detected by
medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
. With autopsies, the principal work of the neuropathologist is to help in the post-mortem diagnosis of various conditions that affect the central nervous system. Biopsies can also consist of the skin. Epidermal nerve fiber density testing (ENFD) is a more recently developed neuropathology test in which a punch skin biopsy is taken to identify small fiber
neuropathies Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve tra ...
by analyzing the nerve fibers of the skin. This test is becoming available in select labs as well as many universities; it replaces the traditional nerve biopsy test as less invasive.


Pulmonary pathology

Pulmonary pathology is a subspecialty of anatomic (and especially surgical) pathology that deals with diagnosis and characterization of
neoplastic A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
and non-neoplastic diseases of the
lung The lungs are the primary Organ (anatomy), organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the vertebral co ...
s and
thoracic The thorax or chest is a part of the anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization o ...
pleura The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls. The inner pleura, called the visceral pleura, covers the surface of each lung and dips bet ...
. Diagnostic specimens are often obtained via bronchoscopic transbronchial biopsy, CT-guided percutaneous biopsy, or video-assisted thoracic surgery. These tests can be necessary to diagnose between infection,
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and mol ...
, or fibrotic conditions.


Renal pathology

Renal pathology is a subspecialty of anatomic pathology that deals with the diagnosis and characterization of disease of the
kidney The kidneys are two reddish-brown bean-shaped organ (anatomy), organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal ...
s. In a medical setting, renal pathologists work closely with nephrologists and transplant surgeons, who typically obtain diagnostic specimens via percutaneous renal biopsy. The renal pathologist must synthesize findings from traditional microscope histology,
electron microscopy An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...
, and
immunofluorescence Immunofluorescence is a technique used for optical microscope, light microscopy with a fluorescence microscope and is used primarily on microbiological samples. This technique uses the specificity of antibodies to their antigen to target fluores ...
to obtain a definitive diagnosis. Medical renal diseases may affect the
glomerulus ''Glomerulus'' () is a common term used in anatomy to describe globular structures of entwined vessels, fibers, or neurons. ''Glomerulus'' is the diminutive of the Latin ''glomus'', meaning "ball of yarn". ''Glomerulus'' may refer to: * the filter ...
, the tubules and
interstitium The interstitium is a wikt:contiguity, contiguous fluid-filled space existing between a structural barrier, such as a cell membrane or the skin, and internal structures, such as organ (anatomy), organs, including muscles and the circulatory syste ...
, the vessels, or a combination of these compartments.


Surgical pathology

Surgical pathology is one of the primary areas of practice for most anatomical pathologists. Surgical pathology involves the gross and microscopic examination of surgical specimens, as well as biopsies submitted by surgeons and non-surgeons such as general internists, medical subspecialists, dermatologists, and interventional radiologists. Often an excised tissue sample is the best and most definitive evidence of disease (or lack thereof) in cases where tissue is surgically removed from a patient. These determinations are usually accomplished by a combination of gross (i.e., macroscopic) and histologic (i.e., microscopic) examination of the tissue, and may involve evaluations of molecular properties of the tissue by immunohistochemistry or other laboratory tests. There are two major types of specimens submitted for surgical pathology analysis: biopsies and surgical resections. A biopsy is a small piece of tissue removed primarily for surgical pathology analysis, most often in order to render a definitive diagnosis. Types of biopsies include core biopsies, which are obtained through the use of large-bore needles, sometimes under the guidance of radiological techniques such as
ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
, CT scan, or
magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. Physics of magnetic resonance imaging#MRI scanner, MRI scanners use strong magnetic ...
. Incisional biopsies are obtained through diagnostic surgical procedures that remove part of a suspicious
lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or Trauma (medicine), trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no ...
, whereas excisional biopsies remove the entire lesion, and are similar to therapeutic surgical resections. Excisional biopsies of
skin lesions A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of ...
and
gastrointestinal The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongu ...
polyps A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa (biology), medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposi ...
are very common. The pathologist's interpretation of a biopsy is critical to establishing the diagnosis of a benign or malignant tumor, and can differentiate between different types and grades of cancer, as well as determining the activity of specific molecular pathways in the tumor. Surgical resection specimens are obtained by the therapeutic surgical removal of an entire diseased area or organ (and occasionally multiple organs). These procedures are often intended as definitive surgical treatment of a disease in which the diagnosis is already known or strongly suspected, but pathological analysis of these specimens remains important in confirming the previous diagnosis.


Clinical pathology

Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the
laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which science, scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: ...
analysis of bodily fluids such as blood and
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...
, as well as tissues, using the tools of
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, properties ...
,
clinical microbiology Medical microbiology, the large subset of microbiology Microbiology () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses ...
,
hematology Hematology (American and British English spelling differences#ae and oe, always spelled haematology in British English) is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to ...
and molecular pathology. Clinical pathologists work in close collaboration with
medical technologist A medical laboratory scientist (MLS) or clinical laboratory scientist (CLS) or medical technologist (MT) performs diagnostic testing of blood and body fluids in clinical laboratories. The scope of a medical laboratory scientist's work begins wit ...
s, hospital administrations, and referring physicians. Clinical pathologists learn to administer a number of visual and microscopic tests and an especially large variety of tests of the biophysical properties of tissue samples involving
automated analyser An automated analyser is a medical laboratory A medical laboratory or clinical laboratory is a laboratory where tests are conducted out on clinical specimens to obtain information about the health of a patient to aid in diagnosis, treatment, and ...
s and
culture Culture () is an umbrella term which encompasses the social behavior, institutions, and Social norm, norms found in human Society, societies, as well as the knowledge, beliefs, arts, laws, Social norm, customs, capabilities, and habits of the ...
s. Sometimes the general term "laboratory medicine specialist" is used to refer to those working in clinical pathology, including medical doctors, Ph.D.s and doctors of pharmacology. Immunopathology, the study of an organism's immune response to infection, is sometimes considered to fall within the domain of clinical pathology.


Hematopathology

Hematopathology is the study of diseases of blood cells (including constituents such as
white blood cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of path ...
,
red blood cells Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek language, Greek ''erythros'' for "red" and ''k ...
, and
platelets Platelets, also called thrombocytes (from Greek language, Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the Coagulation#Coagulation factors, coagulation factors) is to react to bleeding ...
) and the tissues, and organs comprising the hematopoietic system. The term hematopoietic system refers to tissues and organs that produce and/or primarily host hematopoietic cells and includes
bone marrow Bone marrow is a semi-solid biological tissue, tissue found within the Spongy bone, spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It i ...
, the
lymph nodes A lymph node, or lymph gland, is a kidney-shaped Organ (anatomy), organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphoc ...
,
thymus The thymus is a specialized primary Lymphatic system#Structure, lymphoid organ of the immune system. Within the thymus, T cell, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body ada ...
,
spleen The spleen is an organ (biology), organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .
, and other lymphoid tissues. In the United States, hematopathology is a board certified subspecialty (licensed under the American Board of Pathology) practiced by those physicians who have completed a general pathology residency (anatomic, clinical, or combined) and an additional year of fellowship training in hematology. The hematopathologist reviews biopsies of lymph nodes, bone marrows and other tissues involved by an infiltrate of cells of the hematopoietic system. In addition, the hematopathologist may be in charge of flow cytometric and/or molecular hematopathology studies.


Molecular pathology

Molecular pathology is focused upon the study and diagnosis of disease through the examination of molecules within organs, tissues or bodily fluids. Molecular pathology is multidisciplinary by nature and shares some aspects of practice with both anatomic pathology and clinical pathology,
molecular biology Molecular biology is the branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interact ...
,
biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology a ...
,
proteomics Proteomics is the large-scale study of proteins. Proteins are vital parts of living organisms, with many functions such as the formation of structural fibers of muscle tissue, enzymatic digestion of food, or synthesis and replication of DNA. In ...
and
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian fr ...
. It is often applied in a context that is as much scientific as directly medical and encompasses the development of molecular and genetic approaches to the diagnosis and classification of human diseases, the design and validation of predictive biomarkers for treatment response and disease progression, and the susceptibility of individuals of different genetic constitution to particular disorders. The crossover between molecular pathology and
epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and risk factor, determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decision ...
is represented by a related field "
molecular pathological epidemiology Molecular pathological epidemiology (MPE, also molecular pathologic epidemiology) is a Discipline (specialism), discipline combining epidemiology and pathology. It is defined as "epidemiology of molecular pathology and heterogeneity of disease". Pat ...
". Molecular pathology is commonly used in diagnosis of cancer and infectious diseases. Molecular Pathology is primarily used to detect cancers such as melanoma, brainstem glioma, brain tumors as well as many other types of cancer and infectious diseases. Techniques are numerous but include quantitative polymerase chain reaction (qPCR), multiplex PCR,
DNA microarray A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the Gene expression, expression levels of large numbers of genes simult ...
,
in situ hybridization ''In situ'' hybridization (ISH) is a type of hybridization that uses a labeled complementary DNA, RNA or modified nucleic acids strand (i.e., probe) to localize a specific DNA or RNA sequence in a portion or section of tissue (''in situ ...
,
DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. The ...
, antibody-based
immunofluorescence Immunofluorescence is a technique used for optical microscope, light microscopy with a fluorescence microscope and is used primarily on microbiological samples. This technique uses the specificity of antibodies to their antigen to target fluores ...
tissue assays, molecular profiling of pathogens, and analysis of bacterial genes for
antimicrobial resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. P ...
. Techniques used are based on analyzing samples of DNA and RNA. Pathology is widely used for gene therapy and disease diagnosis.


Oral and maxillofacial pathology

Oral and Maxillofacial Pathology is one of nine dental specialties recognized by the
American Dental Association The American Dental Association (ADA) is an American professional association established in 1859 which has more than 161,000 members. Based in the American Dental Association Building in the Near North Side, Chicago, Near North Side of Chicago ...
, and is sometimes considered a specialty of both dentistry and pathology. Oral Pathologists must complete three years of post doctoral training in an accredited program and subsequently obtain diplomate status from the American Board of Oral and Maxillofacial Pathology. The specialty focuses on the diagnosis, clinical management and investigation of diseases that affect the oral cavity and surrounding maxillofacial structures including but not limited to odontogenic, infectious,
epithelial Epithelium or epithelial tissue is one of the four basic types of animal Tissue (biology), tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed Cell (biology), ...
,
salivary gland The salivary glands in mammals are exocrine glands that produce saliva through a system of Duct (anatomy), ducts. Humans have three paired major salivary glands (Parotid gland, parotid, Submandibular gland, submandibular, and sublingual gland, sub ...
,
bone A bone is a rigid organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic ...
and
soft tissue Soft tissue is all the Tissue (biology), tissue in the body that is not hard tissue, hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connective tissue, connects, surrounds or supports internal organs ...
pathologies. It also significantly intersects with the field of dental pathology. Although concerned with a broad variety of diseases of the oral cavity, they have roles distinct from otorhinolaryngologists ("ear, nose, and throat" specialists), and speech pathologists, the latter of which helps diagnose many neurological or
neuromuscular A neuromuscular junction (or myoneural junction) is a chemical synapse Chemical synapses are biological junctions through which neurons' signals can be sent to each other and to non-neuronal cells such as those in neuromuscular junction, ...
conditions relevant to speech phonology or
swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. Swallowing is ...
. Owing to the availability of the
oral cavity In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on t ...
to non-invasive examination, many conditions in the study of oral disease can be diagnosed, or at least suspected, from gross examination, but biopsies, cell smears, and other tissue analysis remain important diagnostic tools in oral pathology.


Medical training and accreditation

Becoming a pathologist generally requires specialty-training after
medical school A medical school is a tertiary educational institution, or part of such an institution, that teaches medicine, and awards a professional degree for physicians. Such medical degrees include the Bachelor of Medicine, Bachelor of Surgery (MBBS, MB ...
, but individual nations vary some in the medical licensing required of pathologists. In the United States, pathologists are physicians ( D.O. or M.D.) who have completed a four-year undergraduate program, four years of medical school training, and three to four years of postgraduate training in the form of a pathology residency. Training may be within two primary specialties, as recognized by the American Board of Pathology:
anatomical pathology Anatomical pathology (''Commonwealth'') or Anatomic pathology (''U.S.'') is a medical specialty that is concerned with the diagnosis of disease based on the macroscopic, microscopic, biochemical, immunologic and molecular examinatio ...
and
clinical Pathology Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the Medical laboratory, laboratory analysis of bodily fluids, such as blood, urine, and tissue homogenates or extracts using the tools of clinic ...
, each of which requires separate board certification. The American Osteopathic Board of Pathology also recognizes four primary specialties: anatomic pathology, dermatopathology, forensic pathology, and
laboratory medicine A medical laboratory or clinical laboratory is a laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which science, scientific or technological research, experiments, and measurement may be perfo ...
. Pathologists may pursue specialised fellowship training within one or more subspecialties of either anatomical or clinical pathology. Some of these subspecialties permit additional board certification, while others do not. In the United Kingdom, pathologists are physicians licensed by the UK
General Medical Council The General Medical Council (GMC) is a public body that maintains the official register of medical practitioners within the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom ...
. The training to become a pathologist is under the oversight of the Royal College of Pathologists. After four to six years of undergraduate medical study, trainees proceed to a two-year foundation program. Full-time training in histopathology currently lasts between five and five and a half years and includes specialist training in surgical pathology, cytopathology, and autopsy pathology. It is also possible to take a Royal College of Pathologists diploma in forensic pathology, dermatopathology, or cytopathology, recognising additional specialist training and expertise and to get specialist accreditation in forensic pathology, pediatric pathology, and neuropathology. All postgraduate medical training and education in the UK is overseen by the General Medical Council. In France, pathology is separated into two distinct specialties, anatomical pathology, and clinical pathology. Residencies for both lasts four years. Residency in anatomical pathology is open to physicians only, while clinical pathology is open to both physicians and
pharmacist A pharmacist, also known as a chemist (English in the Commonwealth of Nations, Commonwealth English) or a druggist (North American and, archaically, Commonwealth English), is a healthcare professional who prepares, controls and distributes med ...
s. At the end of the second year of clinical pathology residency, residents can choose between general clinical pathology and a specialization in one of the disciplines, but they can not practice anatomical pathology, nor can anatomical pathology residents practice clinical pathology.


Overlap with other diagnostic medicine

Though separate fields in terms of medical practice, a number of areas of inquiry in medicine and medical science either overlap greatly with general pathology, work in tandem with it, or contribute significantly to the understanding of the pathology of a given disease or its course in an individual. As a significant portion of all general pathology practice is concerned with
cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Poss ...
, the practice of
oncology Oncology is a branch of medicine that deals with the study, treatment, diagnosis and prevention of cancer. A medical professional who practices oncology is an ''oncologist''. The name's etymological origin is the Greek word ὄγκος (''ó ...
makes extensive use of both anatomical and clinical pathology in diagnosis and treatment. In particular, biopsy, resection, and blood tests are all examples of pathology work that is essential for the diagnoses of many kinds of cancer and for the staging of cancerous masses. In a similar fashion, the tissue and blood analysis techniques of general pathology are of central significance to the investigation of serious
infectious disease An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmiss ...
and as such inform significantly upon the fields of
epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and risk factor, determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decision ...
,
etiology Etiology (pronounced ; alternatively: aetiology or ætiology) is the study of Causality, causation or origination. The word is derived from the Ancient Greek, Greek (''aitiología'') "giving a reason for" (, ''aitía'', "cause"); and (''wikt:-l ...
,
immunology Immunology is a branch of medicineImmunology for Medical Students, Roderick Nairn, Matthew Helbert, Mosby, 2007 and biology that covers the medical study of immune systems in humans, animals, plants and sapient species. In such we can see there ...
, and
parasitology Parasitology is the study of parasites, their host (biology), hosts, and the relationship between them. As a List of biology disciplines, biological discipline, the scope of parasitology is not determined by the organism or environment in questio ...
. General pathology methods are of great importance to biomedical research into disease, wherein they are sometimes referred to as "experimental" or "investigative" pathology.
Medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
is the generating of visual representations of the interior of a body for clinical analysis and medical intervention. Medical imaging reveals details of internal physiology that help medical professionals plan appropriate treatments for tissue infection and trauma. Medical imaging is also central in supplying the
biometric Biometrics are body measurements and calculations related to human characteristics. Biometric authentication Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proof (truth) ...
data necessary to establish baseline features of
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
and
physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying the ...
so as to increase the accuracy with which early or fine-detail abnormalities are detected. These diagnostic techniques are often performed in combination with general pathology procedures and are themselves often essential to developing new understanding of the
pathogenesis Pathogenesis is the process by which a disease or Disease#Disorder, disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes from Anci ...
of a given disease and tracking the progress of disease in specific medical cases. Examples of important subdivisions in medical imaging include
radiology Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...
(which uses the imaging technologies of X-ray
radiography Radiography is an imaging technology, imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnos ...
)
magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. Physics of magnetic resonance imaging#MRI scanner, MRI scanners use strong magnetic ...
,
medical ultrasonography Medical ultrasound includes diagnostic techniques (mainly medical imaging, imaging techniques) using ultrasound, as well as therapeutic ultrasound, therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal ...
(or ultrasound),
endoscopy An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...
,
elastography Elastography is any of a class of medical imaging modalities that map the elasticity (physics), elastic properties and stiffness of soft tissue.Sarvazyan A, Hall TJ, Urban MW, Fatemi M, Aglyamov SR, Garra BSOverview of elastography–an emerging ...
, tactile imaging,
thermography Infrared thermography (IRT), thermal video and/or thermal imaging, is a process where a Thermographic camera, thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are ...
, medical photography,
nuclear medicine Nuclear medicine or nucleology is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease A disease is a particular abnormal condition that negatively affects the structure or ...
and
functional imaging Functional imaging (or physiological imaging) is a medical imaging technique of detecting or measuring changes in metabolism, blood flow, regional chemical composition, and absorption. As opposed to structural imaging, functional imaging centers ...
techniques such as
positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in Metabolism, metabolic processes, and in other physiological activities including bl ...
. Though they do not strictly relay images, readings from diagnostics tests involving
electroencephalography Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...
,
magnetoencephalography Magnetoencephalography (MEG) is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electric current, electrical currents occurring naturally in the human brain, brain, using very sensitive magne ...
, and
electrocardiography Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the hear ...
often give hints as to the state and function of certain tissues in the brain and heart respectively.


Psychopathology

Psychopathology is the study of
mental illness A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitti ...
, particularly of severe disorders. Informed heavily by both
psychology Psychology is the science, scientific study of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconscious phenomena, including feelings and thoughts. It is an academic discipline of immens ...
and
neurology Neurology (from el, wikt:νεῦρον, νεῦρον (neûron), "string, nerve" and the suffix wikt:-logia, -logia, "study of") is the branch of specialty (medicine), medicine dealing with the diagnosis and treatment of all categories of co ...
, its purpose is to classify mental illness, elucidate its underlying causes, and guide clinical
psychiatric Psychiatry is the specialty (medicine), medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psych ...
treatment accordingly. Although diagnosis and classification of mental norms and disorders is largely the purview of psychiatry—the results of which are guidelines such as the
Diagnostic and Statistical Manual of Mental Disorders The ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM; latest edition: DSM-5-TR, published in March 2022) is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common langua ...
, which attempt to classify mental disease mostly on behavioural evidence, though not without controversyDalal PK, Sivakumar T. (2009
Moving towards ICD-11 and DSM-5: Concept and evolution of psychiatric classification.
Indian Journal of Psychiatry, Volume 51, Issue 4, Page 310-319.
—the field is also heavily, and increasingly, informed upon by
neuroscience Neuroscience is the science, scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a Multidisciplinary approach, multidisciplinary science that combines physiology, an ...
and other of the biological cognitive sciences. Mental or social disorders or behaviours seen as generally unhealthy or excessive in a given individual, to the point where they cause harm or severe disruption to the person's lifestyle, are often called "pathological" (e.g., pathological gambling or pathological liar).


Non-humans

Although the vast majority of lab work and research in pathology concerns the development of disease in humans, pathology is of significance throughout the biological sciences. Two main catch-all fields exist to represent most complex organisms capable of serving as host to a pathogen or other form of disease: veterinary pathology (concerned with all non-human species of kingdom of
Animalia Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
) and
phytopathology Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungus, fung ...
, which studies disease in plants.


Veterinary pathology

Veterinary pathology covers a vast array of species, but with a significantly smaller number of practitioners, so understanding of disease in non-human animals, especially as regards veterinary practice, varies considerably by species. Nonetheless, significant amounts of pathology research are conducted on animals, for two primary reasons: 1) The origins of diseases are typically
zoonotic A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has Cross-species transmission, jumped from a non-human (usuall ...
in nature, and many infectious pathogens have animal vectors and, as such, understanding the mechanisms of action for these pathogens in non-human hosts is essential to the understanding and application of
epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and risk factor, determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decision ...
and 2) those animals that share physiological and genetic traits with humans can be used as surrogates for the study of the disease and potential treatments as well as the effects of various synthetic products. For this reason, as well as their roles as
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool Wool is the textile fibre obtained from sheep an ...
and companion animals,
mammals Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a ...
generally have the largest body of research in veterinary pathology. Animal testing remains a controversial practice, even in cases where it is used to research treatment for human disease. As in human medical pathology, the practice of veterinary pathology is customarily divided into the two main fields of anatomical and clinical pathology.


Plant pathology

Although the pathogens and their mechanics differ greatly from those of animals, plants are subject to a wide variety of diseases, including those caused by
fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...
,
oomycete Oomycota forms a distinct phylogeny, phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are mycelia, filamentous and heterotrophic, and can reproduce both Sexual reproduction, sexually and Asexual reproductio ...
s,
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometre The micrometre (Amer ...
,
virus A virus is a wikt:submicroscopic, submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and ...
es,
viroid Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike virus A virus is a wikt:submicroscopic, submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. ...
s, virus-like organisms,
phytoplasma Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect Vector (epidemiology), vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who term ...
s,
protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of Unicellular organism, single-celled eukaryotes, either free-living or Parasitism, parasitic, that feed on organic matter such as other microorganisms or o ...
,
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
s and
parasitic plant A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All Parasite, parasitic plants develop a specialized organ ...
s. Damage caused by
insects Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, Thorax (ins ...
,
mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...
s,
vertebrate Vertebrates () comprise all animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually ...
, and other small herbivores is not considered a part of the domain of plant pathology. The field is connected to
plant disease epidemiology Plant disease epidemiology is the study of disease in plant populations. Much like diseases of humans and other animals, plant pathology, plant diseases occur due to pathogens such as bacterium, bacteria, plant virus, viruses, fungus, fungi, oomyce ...
and especially concerned with the
horticulture Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
of species that are of high importance to the
human diet Human nutrition deals with the provision of essential nutrient A nutrient is a Chemical substance, substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungus, ...
or other human utility.


See also

*
Biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves extraction of sampling (medicine), sample Cell (biology), cells or Biologica ...
*
Causal inference Causal inference is the process of determining the independent, actual effect of a particular phenomenon that is a component of a larger system. The main difference between causal inference and inference of association (statistics), association is ...
*
Cell (biology) The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a Cell membrane, membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of ...
*
Disease A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medica ...
* Environmental pathology *
Epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and risk factor, determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decision ...
*
Etiology (medicine) Cause, also known as etiology () and aetiology, is the reason Reason is the capacity of Consciousness, consciously applying logic by Logical consequence, drawing conclusions from new or existing information, with the aim of seeking the truth. I ...
*
Hematology Hematology (American and British English spelling differences#ae and oe, always spelled haematology in British English) is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to ...
*
Histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larg ...
*
Immunology Immunology is a branch of medicineImmunology for Medical Students, Roderick Nairn, Matthew Helbert, Mosby, 2007 and biology that covers the medical study of immune systems in humans, animals, plants and sapient species. In such we can see there ...
* List of pathologists *
Medical diagnosis Medical diagnosis (abbreviated Dx, Dx, or Ds) is the process of determining which disease or condition explains a person's symptoms and medical sign, signs. It is most often referred to as diagnosis with the medicine, medical context being implic ...
*
Medical jurisprudence Medical jurisprudence or legal medicine is the branch of science Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the unive ...
*
Medicine Medicine is the science and Praxis (process), practice of caring for a patient, managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, and Health promotion ...
*
Microbiology Microbiology () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriolog ...
*
Micrography Micrography (from Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the as ...
*
Microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...
* Minimally-invasive procedures *
Oncology Oncology is a branch of medicine that deals with the study, treatment, diagnosis and prevention of cancer. A medical professional who practices oncology is an ''oncologist''. The name's etymological origin is the Greek word ὄγκος (''ó ...
*
Parasitology Parasitology is the study of parasites, their host (biology), hosts, and the relationship between them. As a List of biology disciplines, biological discipline, the scope of parasitology is not determined by the organism or environment in questio ...
*
Pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ ...
*
Pathogenesis Pathogenesis is the process by which a disease or Disease#Disorder, disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes from Anci ...
*
Pathophysiology Pathophysiology ( physiopathology) – a convergence of pathology with physiology – is the study of the disordered biological process, physiological processes that cause, result from, or are otherwise associated with a disease or injur ...
*
Precision medicine Precision, precise or precisely may refer to: Science, and technology, and mathematics Mathematics and computing (general) * Accuracy and precision, measurement deviation from true value and its scatter * Significant figures, the number of digit ...
*
Spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectrum, electromagnetic spectra that result from the interaction between Electromagnetism, electromagnetic radiation and matter as a function of the wavelengt ...
*
Speech–language pathology Speech-language pathology (or speech and language pathology) is a healthcare field of expertise practiced globally. Speech-language pathology (SLP) specializes in the evaluation, diagnosis, treatment, and prevention of communication disorders ( ...
* Telepathology


References


External links

*
American Society for Clinical Pathology (ASCP) American Society for Investigative Pathology (ASIP) Pathpedia online pathology resource
Comprehensive pathology website with numerous resources.
College of American Pathologistshumpath.com
(Atlas in Human Pathology)
Intersociety Council for Pathology Training (ICPI)Pathological Society of Great Britain and IrelandRoyal College of Pathologists (UK)Royal College of Pathologists of Australasia (Australia & Oceania)United States and Canadian Academy of Pathology
* ttp://atlases.muni.cz Atlases: High Resolution Pathology Images {{Authority control Branches of biology