epithelial-myoepithelial carcinoma
Rare low-grade malignant salivary gland tumor with dual cell population. Characterized by epithelial cells surrounded by myoepithelial cells in a biphasic pattern.
Full Definition
A rare malignant salivary gland neoplasm characterized by a distinctive biphasic growth pattern consisting of inner ductal epithelial cells surrounded by outer myoepithelial cells. This tumor most commonly arises in the parotid gland but can occur in any major or minor salivary gland. It typically presents as a slow-growing, painless mass and is generally considered low-grade with good prognosis when completely excised. However, local recurrence can occur if surgical margins are inadequate, and rare cases of transformation to high-grade carcinoma have been reported. The biphasic pattern is best appreciated on immunohistochemical staining, where the inner cells are positive for cytokeratins and the outer myoepithelial cells are positive for smooth muscle actin and S-100 protein.
Usage
Usage note: Often abbreviated as EMC in clinical documentation.
In Context
- "The parotid mass was diagnosed as epithelial-myoepithelial carcinoma based on the characteristic biphasic histologic pattern." — Pathology report
- "Complete surgical excision with negative margins is crucial for epithelial-myoepithelial carcinoma to prevent local recurrence." — Treatment planning