Epithelial-myoepithelial carcinoma

A rare type of salivary gland tumor

Epithelial-myoepithelial carcinoma (EMC) is a rare type of salivary gland tumor characterized by its biphasic cellular composition, consisting of both epithelial and myoepithelial components. This tumor is most commonly found in the parotid gland, which is the largest of the salivary glands, but it can also occur in other salivary glands and occasionally in other locations.

Histopathology

Epithelial-myoepithelial carcinoma is distinguished by its unique histological appearance. The tumor is composed of duct-like structures lined by an inner layer of cuboidal epithelial cells and an outer layer of clear myoepithelial cells. The clear appearance of the myoepithelial cells is due to the presence of abundant glycogen in the cytoplasm. The stroma surrounding the tumor can vary from being scant to having a myxoid or hyalinized appearance.

Clinical Presentation

Patients with epithelial-myoepithelial carcinoma typically present with a slow-growing, painless mass in the region of the affected salivary gland. Due to its indolent nature, the tumor may be present for several years before diagnosis. In some cases, the tumor may cause facial nerve dysfunction if it invades or compresses the facial nerve.

Diagnosis

The diagnosis of epithelial-myoepithelial carcinoma is primarily based on histological examination of a biopsy specimen. Immunohistochemistry can be used to confirm the biphasic nature of the tumor, with epithelial cells typically expressing cytokeratin and myoepithelial cells expressing S-100 protein, smooth muscle actin, and other myoepithelial markers.

Treatment

The primary treatment for epithelial-myoepithelial carcinoma is surgical excision with clear margins. Due to the potential for local recurrence, complete surgical removal is essential. In some cases, radiation therapy may be considered, especially if surgical margins are positive or if the tumor is inoperable.

Prognosis

The prognosis for patients with epithelial-myoepithelial carcinoma is generally favorable, with a relatively low rate of metastasis. However, the tumor can recur locally, and long-term follow-up is recommended. The overall survival rate is high, but the risk of recurrence necessitates careful monitoring.

Related pages

• Salivary gland tumor
• Parotid gland
• Myoepithelial cell
• Histopathology