Salivary gland tumours, or

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 ...

s, are

tumours 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 ...

that form in the tissues of

salivary glands The salivary glands in many vertebrates including 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, submandibula ...

. The salivary glands are classified as major or minor. The major salivary glands consist of the

parotid The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the ...

submandibular The submandibular ganglion (or submaxillary ganglion in older texts) is part of the human autonomic nervous system. It is one of four parasympathetic ganglia of the head and neck. (The others are the otic ganglion, pterygopalatine ganglion, and ci ...

, and

sublingual Sublingual (List of abbreviations used in medical prescriptions, abbreviated SL), from the Latin for "under the tongue", refers to the pharmacological route of administration by which substances diffuse into the blood through Tissue (biology), t ...

glands. The minor salivary glands consist of 800 to 1000 small mucus-secreting glands located throughout the lining of the

oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or ora ...

cavity. People with these types of tumours may be asymptomatic.

Presentation

Salivary gland tumours usually present as a lump or swelling in the affected gland which may or may not have been present for a long time. The lump may be accompanied by symptoms of duct blockage (e.g.

xerostomia Xerostomia, also known as dry mouth, is a subjective complaint of dryness in the mouth, which may be associated with a change in the composition of saliva, reduced salivary flow, or have no identifiable cause. This symptom is very common and is o ...

). Usually, in their early stages, it is not possible to distinguish a benign tumour from a malignant one. One of the key differentiating symptoms of malignant growth is nerve involvement; for example, signs of

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of ta ...

damage (e.g.

facial palsy Facial nerve paralysis is a common problem that involves the paralysis of any structures innervated by the facial nerve. The pathway of the facial nerve is long and relatively convoluted, so there are a number of causes that may result in facial ...

) are associated with malignant parotid tumours. Facial pain and

paraesthesia Paresthesia is a sensation of the skin that may feel like numbness (''hypoesthesia''), tingling, pricking, chilling, or burning. It can be temporary or chronic and has many possible underlying causes. Paresthesia is usually painless and can oc ...

are also very often associated with malignant tumours. Other red flag symptoms which may suggest malignancy and warrant further investigation are fixation of the lump to the overlying skin,

ulcer An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughin ...

ation and induration (hardening) of the mucosa. Massive tumor of the parotid gland

Diagnosis

Many diagnostic methods can be used to determine the type of salivary gland tumour and if it is benign or malignant. Examples of diagnostic methods include: Physical exam and history: An exam of the body to check general signs of health. The head, neck, mouth, and throat will be checked for signs of disease, such as lumps or anything else that seems unusual. A

medical history The medical history, case history, or anamnesis (from Greek: ἀνά, ''aná'', "open", and μνήσις, ''mnesis'', "memory") of a patient is a set of information the physicians collect over medical interviews. It involves the patient, and ev ...

will also be taken. Endoscopy: A procedure to look at organs and tissues inside the body to check for abnormal areas. For salivary gland cancer, an

endoscope An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern ...

is inserted into the mouth to look at the mouth, throat, and larynx. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. MRI or CT Scan: These tests can confirm the presence of a tumour. An MRI or CT Scan can also show whether

metastasis Metastasis is a pathogenic agent's spreading from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, ...

has occurred. Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. Fine needle aspiration (FNA) biopsy: The removal of tissue or fluid using a thin needle. An FNA is the most common type of biopsy used for salivary gland cancer and has been shown to produce accurate results when differentiating between benign and malignant tumours. Radiographs: An OPG (orthopantomogram) can be taken to rule out mandibular involvement. A chest radiograph may also be taken to rule out any secondary tumours. Ultrasound: Ultrasound can be used to initially assess a tumour that is located superficially in either the submandibular or parotid gland. It can distinguish an intrinsic from an extrinsic neoplasm. Ultrasonic images of malignant tumours include ill-defined margins. Furthermore, high resolution ultrasound can identify the exact tumour location within the parotid gland, its relationship to the retromandibular vein and assist surgical excision.

Classification

Relative incidence of submandibular tumors

Due to the diverse nature of salivary gland tumours, many different terms and classification systems have been used. Perhaps the most widely used currently is that system proposed by the

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

in 2005. This system defines five broad categories of salivary gland neoplasms: benign epithelial, malignant epithelial, soft tissue, hematolymphoid, and secondary. Benign epithelial tumours *

Pleomorphic adenoma Pleomorphic adenoma (or benign mixed tumor) is a common benign salivary gland neoplasm characterised by neoplastic proliferation of epithelial (ductal) cells along with myoepithelial components, having a malignant potentiality. It is the most comm ...

Coronal MRI showing right parotid adenoid cystic carcinoma with perineural spread of tumor

Warthin's tumor Warthin's tumor, also known as papillary cystadenoma lymphomatosum, is a benign cystic tumor of the salivary glands containing abundant lymphocytes and germinal centers (lymph node-like stroma). It is named for pathologist Aldred Scott Warthin, ...

Myoepithelioma Myoepithelioma of the head and neck, also myoepithelioma, is a salivary gland tumour of the head and neck that is usually benign. When malignant, which is exceedingly rare, they are known as malignant myoepithelioma or Myoepithelial carcinoma, and ...

Basal cell adenoma Basal cell adenoma is a rare, low-grade benign salivary gland neoplasm. The most common involved site is the parotid gland, however other possible sites include the submandibular gland The paired submandibular glands (historically known as subma ...

Oncocytoma An oncocytoma is a tumor made up of oncocytes, epithelial cell (biology), cells characterized by an excessive amount of mitochondria, resulting in an abundant acidophilic, granular cytoplasm. The cells and the tumor that they compose are often be ...

Canalicular adenoma Canalicular adenoma is a type of growth that occurs in human salivary glands. It is a benign growth which occurs in the epithelial cells, and is typically arranged in columns of cells that form interconnecting cords. Canalicular adenoma is a very ...

* Lymphadenoma ** ''

Sebaceous lymphadenoma Sebaceous lymphadenoma is a benign tumour of the salivary gland. Diagnosis Sebaceous lymphadenoma is a tissue diagnosis, e.g. salivary gland biopsy. It may be confused with a number of benign and malignant neoplasms, including Warthin tumour, m ...

'' ** '' Nonsebaceous lymphadenoma'' * Ductal papilloma ** ''

Inverted ductal papilloma An inverted papilloma, also known as Ringertz tumour, is a type of tumor in which surface epithelial cells grow downward into the underlying supportive tissue. It may occur in the nose and/or sinuses or in the urinary tract (bladder, renal pelv ...

'' ** ''

Intraductal papilloma Intraductal papillomas of the breast are benign lesions with an incidence of approximately 2-3% in humans. They result from abnormal proliferation of the epithelial cells lining the breast ducts. Two types of intraductal papillomas are generally ...

'' ** '' Sialadenoma papilliferum'' *

Cystadenoma Cystadenoma is a type of cystic adenoma. When malignant, it is called cystadenocarcinoma. Classification When not otherwise specified, the ICD-O coding is 8440/0. However, the following classifications also exist: By form * serous cystadenoma ( ...

* Malignant epithelial tumours **

Acinic cell carcinoma Acinic cell carcinoma is a malignant epithelial neoplasm that shows differentiation toward serous acinar cells of salivary gland origin. First described by Godwin et al. in 1954, it represents approximately 6-15% of all salivary gland malignancies ...

Mucoepidermoid carcinoma Mucoepidermoid carcinoma (MEC) is the most common type of minor salivary gland malignancy in adults. Mucoepidermoid carcinoma can also be found in other organs, such as bronchi, lacrimal sac, and thyroid gland. Mucicarmine staining is one stain us ...

Adenoid cystic carcinoma Adenoid cystic carcinoma is a rare type of cancer that can exist in many different body sites. This tumor most often occurs in the salivary glands, but it can also be found in many anatomic sites, including the breast, lacrimal gland, human lung, ...

Polymorphous low-grade adenocarcinoma Polymorphous low-grade adenocarcinoma (PLGA) is a rare, asymptomatic, slow-growing malignant salivary gland tumor. It is most commonly found in the palate. The name of the tumor derives from the fact that: *It has a varied microscopic architectura ...

Epithelial-myoepithelial carcinoma Epithelial-myoepithelial carcinoma is thought to be of intercalated duct origin. This is the first part of the exocrine gland ductal system in salivary glands, lined with cuboidal epithelium. Myoepithelial cells are thought to line the basal side ...

** Clear cell carcinoma, not otherwise specified ** Basal cell adenocarcinoma **

Sebaceous carcinoma Sebaceous carcinoma, also known as sebaceous gland carcinoma (SGc), sebaceous cell carcinoma, and meibomian gland carcinoma, is an uncommon malignant cutaneous (skin) tumor. Most are typically about 1.4 cm at presentation. SGc originates fro ...

Sebaceous lymphadenocarcinoma A sebaceous gland or oil gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in th ...

Cystadenocarcinoma Cystadenocarcinoma is a malignant tumor that arises from glandular epithelial cells and forms cystic structures. It is most commonly found in the ovaries and pancreas, but it can also develop in other organs. The exact cause of cystadenocarcinoma is ...

Low-grade cribriform cystadenocarcinoma Grade most commonly refers to: * Grading in education, a measurement of a student's performance by educational assessment (e.g. A, pass, etc.) * A designation for students, classes and curricula indicating the number of the year a student has reach ...

Mucinous adenocarcinoma A mucinous neoplasm (also called colloid neoplasm) is an abnormal and excessive growth of tissue (neoplasia) with associated mucin (a fluid that sometimes resembles thyroid colloid). It arises from epithelial cells that line certain internal organs ...

Oncocytic carcinoma An oncocytoma is a tumor made up of oncocytes, epithelial cells characterized by an excessive amount of mitochondria, resulting in an abundant acidophilic, granular cytoplasm. The cells and the tumor that they compose are often benign but someti ...

Salivary duct carcinoma Salivary duct carcinoma (SDC) is a rare type of aggressive cancer that arises from the salivary glands. It is predominantly seen in men and, generally, has a poor prognosis. Other high grade carcinomas can mimic SDC. About 40-60% of SDC arise in pl ...

** Salivary duct carcinoma, not otherwise specified ** Adenocarcinoma, not otherwise specified ** Myoepithelial carcinoma ** Carcinoma ex pleomorphic adenoma **

Mammary analogue secretory carcinoma Mammary analogue secretory carcinoma (MASC), also termed MASCSG, (the "SG" subscript indicates salivary gland) is a salivary gland neoplasm. It is a secretory carcinoma which shares the microscopic pathologic features with other types of secretory ...

Carcinosarcoma Carcinosarcomas are malignant tumors that consist of a Mixed tumor, mixture of carcinoma (or epithelial cancer) and sarcoma (or mesenchymal/connective tissue cancer). Carcinosarcomas are rare tumors, and can arise in diverse organs, such as the ski ...

Metastasizing pleomorphic adenoma Metastasis is a pathogenic agent's spreading from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, ...

Squamous cell carcinoma Squamous-cell carcinoma (SCC), also known as epidermoid carcinoma, comprises a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the ...

Large cell carcinoma Large means of great size. Large may also refer to: Mathematics * Arbitrarily large, a phrase in mathematics * Large cardinal, a property of certain transfinite numbers * Large category, a category with a proper class of objects and morphisms ( ...

** Lymphoepithelial carcinoma **

Sialoblastoma A sialoblastoma is a low-grade salivary gland neoplasm that recapitulates primitive salivary gland Primordium, anlage. It has previously been referred to as ''congenital basal cell adenoma'', ''embryoma'', or ''basaloid adenocarcinoma''. It is an e ...

* Soft tissue tumours **

Hemangioma A hemangioma or haemangioma is a usually benign vascular tumor derived from blood vessel cell types. The most common form, seen in infants, is an infantile hemangioma, known colloquially as a "strawberry mark", most commonly presenting on the sk ...

* Hematolymphoid tumours **

Hodgkin lymphoma Hodgkin lymphoma (HL) is a type of lymphoma in which cancer originates from a specific type of white blood cell called lymphocytes, where multinucleated Reed–Sternberg cells (RS cells) are present in the lymph nodes. The condition was named a ...

Diffuse large B-cell lymphoma Diffuse large B-cell lymphoma (DLBCL) is a cancer of B cells, a type of lymphocyte that is responsible for producing antibodies. It is the most common form of non-Hodgkin lymphoma among adults, with an annual incidence of 7–8 cases per 100,000 ...

Extranodal marginal zone B cell lymphoma Marginal zone lymphomas, also known as marginal zone B-cell lymphomas (MZLs), are a heterogeneous group of lymphomas that derive from the malignant transformation of marginal zone B-cells. Marginal zone B cells are innate lymphoid cells that norm ...

* Secondary tumours (i.e. a tumour which has

metastasized Metastasis is a pathogenic agent's spreading from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, ...

to the salivary gland from a distant location) Others, not included in the WHO classification above, include: * Intraosseous (central) salivary gland tumours * Hybrid tumours (i.e. a tumour displaying combined forms of histologic tumour types) **

Hybrid carcinoma Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

** Others * Others ** Keratocystoma ** Sialolipoma

Treatment

Early-stage lesions may be able to be treated surgically. More advanced or unresectable cancers tend to be treated with radiotherapy (RT) alone or chemoradiotherapy (CRT), which hampered the comparison of the efficacy of RT alone with that of surgery combined with adjuvant RT. But some effort had been made to reflect the role of surgery in salivary gland tumours. Treatment may include the following: *

Surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

Complete surgical resection, with adequate free margins, is currently the mainstay treatment for salivary gland tumours. However elective treatment of the N0 neck region remains a controversial topic *

Radiotherapy Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle ...

If a salivary gland tumour is cancerous, Radiation Therapy may be necessary

Fast neutron therapy Fast neutron therapy utilizes high energy neutrons typically between 50 and 70 MeV to treat cancer. Most fast neutron therapy beams are produced by reactors, cyclotrons (d+Be) and linear accelerators. Neutron therapy is currently available i ...

has been used successfully to treat salivary gland tumours, and has shown to be significantly more effective than photons in studies treating unresectable salivary gland tumours. *

Chemotherapy Chemotherapy (often abbreviated chemo, sometimes CTX and CTx) is the type of cancer treatment that uses one or more anti-cancer drugs (list of chemotherapeutic agents, chemotherapeutic agents or alkylating agents) in a standard chemotherapy re ...

Currently little is known about the efficacy of chemotherapy in treating salivary gland tumours. Chemotherapy, which plays an important role in systemic therapy, is generally reserved for the palliative treatment of symptomatic locally recurrent and/or metastatic disease that is not amenable to further surgery or radiation. Conventional chemotherapy regimens, such as cisplatin and 5-FU or CAP (cisplatin, doxorubicin, and cyclophosphamide) are still utilized as first-line therapy for those with advanced lesions. Targeted therapy - Due to the poor results with chemotherapy, it's urgent to explore novel therapeutic interventions for this disease. And great expectations have been put into individualized therapies: in particular, the EGF receptors family (EGFR and HER2), KIT and androgen receptors are the most commonly investigated molecular targets in SGCs. Their expression seems not to be linked to its pathogenetic role in the development of SGCs, but more to the histogenetic origin of the tumour cells. Various targeted agents, such as imatinib, cetuximab, gefitinib, trastuzumab, had been used for exploring new treatment for salivary gland tumours, but on account of the rare incidence of salivary gland tumours, the number of cases available on targeted therapy for analysis is relatively small.

Epidemiology

Little is known about the total incidence of salivary gland tumours as most benign tumours go unrecorded in national cancer registries. The majority of salivary tumours are benign (65-70%). Within the parotid gland 75 - 80% of tumours are benign. Around 50% of the tumours found in the submandibular glands are benign. Sublingual gland tumours are very rare but if present, they are most likely to be malignant. Saku et al. in 1997 and Venturi in 2021, reported the causal role for ionizing radiation in salivary gland tumorigenesis, particularly for mucoepidermoid carcinoma. In the United States, salivary gland cancers are uncommon with an incidence rate of 1.7 in 100000 between 2009 and 2013.

References

External links

Salivary gland cancer
entry in the public domain NCI Dictionary of Cancer Terms {{DEFAULTSORT:Salivary Gland Cancer Rare cancers * Salivary gland pathology