Mucoepidermoid carcinoma (MEC) is the most common type of minor

salivary gland The salivary glands in many vertebrates including 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 min ...

malignancy in adults. Mucoepidermoid carcinoma can also be found in other organs, such as

bronchi A bronchus ( ; : bronchi, ) is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi to branch from the trachea at the carina are the right main bronchus and the left main bronchus. Thes ...

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 th ...

, and

thyroid gland The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by ...

. 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. Image:Mucoepidermoid carcinoma (2) HE stain.jpg, Histopathologic image of mucoepidermoid carcinoma of the major salivary gland. H & E stain Image:Mucoepidermoid carcinoma (3) HE stain.jpg, Histopathologic image of mucoepidermoid carcinoma of the major salivary gland. The same lesion as shown in a filename "Mucoepidermoid carcinoma (2) HE stain.jpg". H & E stain Image:Mucoepidermoid carcinoma (1) AB-PAS stain.jpg, Histopathologic image of mucoepidermoid carcinoma. Postoperative recurrence of the submandibular tumor. Alcian blue-PAS stain

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 three main types: "reciprocal", "nonreciprocal" and "Robertsonian" transloc ...

resulting in a MECT1-MAML2

fusion gene In genetics, 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 ...

. 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 des ...

coactivator MECT1 (also known as CRTC1, TORC1 or WAMTP1) is fused to the transactivation domain of the Notch coactivator MAML2. A possible association with radiation exposure has been reported. It has also been proposed that mucoepidermoid tumors arise from subepithelial mucous glands of the upper respiratory or digestive tracts.

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 '' Betaherp ...

(CMV) has been strongly implicated in a 2011 research. File:Relative incidence of parotid tumors.png, Relative incidence of parotid tumors, showing mucoepidermoid carcinoma at top right. 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