Mucoepidermoid carcinoma (MEC) is the most common type of minor
salivary gland
The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary ...
malignancy in adults. Mucoepidermoid carcinoma can also be found in other organs, such as
bronchi
A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...
,
lacrimal sac
The lacrimal sac or lachrymal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla. It connects the lacrimal canaliculi, which drain tears from the ...
,
and
thyroid gland
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
.
Mucicarmine staining is one stain used by pathologist for detection.
Signs and symptoms
Presents as painless, slow-growing mass that is firm or hard. Most appear clinically as mixed tumors. Usually occurs at 30–50 years of age. More predilection towards female sex.
Diagnosis
Histology
This tumor is not encapsulated and is characterized by squamous cells, mucus-secreting cells, and intermediate cells.
Molecular biology
Mucoepidermoid carcinomas of the salivary and bronchial glands are characterized by a recurrent t(11;19)(q21;p13)
chromosomal translocation
In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal-, and Robertsonian translocation. Reciprocal transl ...
resulting in a MECT1-MAML2
fusion gene A fusion gene is a hybrid gene formed from two previously independent genes. It can occur as a result of translocation, interstitial deletion, or chromosomal inversion. Fusion genes have been found to be prevalent in all main types of human neopla ...
.
The CREB-binding domain of the
CREB
CREB-TF (CREB, cAMP response element-binding protein) is a cellular transcription factor. It binds to certain DNA sequences called cAMP response elements (CRE), thereby increasing or decreasing the transcription of the genes. CREB was first de ...
coactivator
MECT1 (also known as CRTC1, TORC1 or WAMTP1) is fused to the transactivation domain of the Notch coactivator
MAML2.
A possible association with
papillomavirus
''Papillomaviridae'' is a family of non- enveloped DNA viruses whose members are known as papillomaviruses. Several hundred species of papillomaviruses, traditionally referred to as "types", have been identified infecting all carefully inspected ...
has been reported.
Prognosis
Generally, there is a good prognosis for low-grade tumors, and a poor prognosis for high-grade tumors, however recent research have found reoccurring low grade tumors also have a poor prognosis.
Treatment
Surgery is the recommended treatment for localised resectable disease.
When the tumour is incompletely resected (positive margins) post-operative radiotherapy gives local control comparable to a complete resection (clear margins).
Sometimes when surgery is not possible due to extent of disease or if a patient is too frail for surgery, or declines surgery, palliative radiotherapy may be helpful. There has been a report of a case where low dose radiotherapy achieve disease response and control for more than 4 years.
In patients with metastatic disease, chemotherapy response tends to be low (27% partial response rate) and short lived.
Epidemiology
Occurs in adults, with peak incidence from 20–40 years of age. A causal link with
cytomegalovirus
''Cytomegalovirus'' (''CMV'') (from ''cyto-'' 'cell' via Greek - 'container' + 'big, megalo-' + -''virus'' via Latin 'poison') is a genus of viruses in the order '' Herpesvirales'', in the family '' Herpesviridae'', in the subfamily '' Betah ...
(CMV) has been strongly implicated in a 2011 research.
[ Updated: Jan 13, 2021]
Diagrams by Mikael Häggström, MD
File:Relative incidence of submandibular tumors.png, Relative incidence of submandibular tumors, showing mucoepidermoid carcinoma at top right.[
]
References
External links
{{DEFAULTSORT:Mucoepidermoid Carcinoma
Salivary gland neoplasia
Cytomegalovirus-associated diseases