Dysplasia is any of various types of abnormal growth or development of cells (

microscopic scale 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 or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...

) or organs ( macroscopic scale), and the abnormal

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures v ...

or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopic scale include epithelial dysplasia and fibrous dysplasia of bone. Dysplasias on a mainly macroscopic scale include hip dysplasia, myelodysplastic syndrome, and multicystic dysplastic kidney. In one of the modern histopathological senses of the term, dysplasia is sometimes differentiated from other categories of tissue change including

hyperplasia Hyperplasia (from ancient Greek ὑπέρ ''huper'' 'over' + πλάσις ''plasis'' 'formation'), or hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount of organic tissue that results from cell proliferatio ...

, metaplasia, and neoplasia, and dysplasias are thus generally not

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

ous. An exception is that the myelodysplasias include a range of benign, precancerous, and cancerous forms. Various other dysplasias tend to be precancerous. The word's meanings thus cover a spectrum of histopathological variations.

Microscopic scale

Epithelial dysplasia

Epithelial dysplasia consists of an expansion of immature cells (such as cells of the

ectoderm The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...

), with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process. The term dysplasia is typically used when the cellular abnormality is restricted to the originating tissue, as in the case of an early, ''in-situ''

neoplasm 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 ...

. Dysplasia, in which cell maturation and differentiation are delayed, can be contrasted with metaplasia, in which cells of one mature, differentiated type are replaced by cells of another mature, differentiated type.

Myelodysplastic syndrome

''Myelodysplastic syndromes'' (''MDS'') are a group of

s in which immature

blood cell A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a cell produced through hematopoiesis and found mainly in the blood. Major types of blood cells include red blood cells (erythrocytes), white blood cells (leukocytes) ...

s in the

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 ...

do not mature and therefore do not become healthy blood cells. Problems with blood cell formation result in some combination of low red blood cells, low platelets, and

low white blood cells Leukopenia () is a decrease in the number of leukocytes (WBC). Found in the blood, they are the white blood cells, and are the body's primary defense against an infection. Thus the condition of leukopenia places individuals at increased risk of in ...

. Some types have an increase in immature blood cells, called blasts, in the bone marrow or

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

Fibrous dysplasia of bone

Fibrous dysplasia of bone is a disorder where normal

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

and marrow is replaced with fibrous tissue, resulting in formation of bone that is weak and prone to expansion. As a result, most complications result from fracture, deformity, functional impairment and pain.

Macroscopic scale

Hip dysplasia

''Hip dysplasia'' is an abnormality of the hip joint where the socket portion does not fully cover the ball portion, resulting in an increased risk for

joint dislocation A joint dislocation, also called luxation, occurs when there is an abnormal separation in the joint, where two or more bones meet.Dislocations. Lucile Packard Children’s Hospital at Stanford. Retrieved 3 March 2013 A partial dislocation is refe ...

. Hip dysplasia may occur at birth or develop in early life. Regardless, it does not typically produce symptoms in babies less than a year old. Occasionally one leg may be shorter than the other. The left hip is more often affected than the right. Complications without treatment can include

arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...

, limping, and low back pain.

Multicystic dysplastic kidney

''Multicystic dysplastic kidney'' (''MCDK'') is a condition that results from the malformation of the

kidney The kidneys are two reddish-brown bean-shaped 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 arteries; blo ...

during fetal development. The kidney consists of irregular cysts of varying sizes. Multicystic dysplastic kidney is a common type of renal cystic disease, and it is a cause of an abdominal mass in infants.

Etymology

From

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...

δυσ- ''dys-'', "bad" or "difficult" and πλάσις ''plasis'', "formation". The equivalent surface analysis, in parallel with

classical compound Neoclassical compounds are compound words composed from combining forms (which act as affixes or stems) derived from classical Latin or ancient Greek roots. New Latin comprises many such words and is a substantial component of the technical an ...

s, is '' dys-'' + '' -plasia''.