Mucoepidermoid Carcinoma Histology — ORE Part 1 MCQ
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Correct answer: C — Mucoepidermoid carcinoma
Mucoepidermoid carcinoma (MEC) is definitively diagnosed by the simultaneous presence of three cell types: mucous (mucus-producing), epidermoid (squamous), and intermediate cells arranged in sheets or cystic patterns. The stem's description of 'sheets of mucus-producing cells, epidermoid cells, and intermediate cells in a biphasic pattern' is pathognomonic for MEC. Pleomorphic adenoma (benign) shows mixed epithelial-mesenchymal patterns with stromal diversity (myxoid, chondroid stroma), not this cellular triplet. Adenoid cystic carcinoma presents a distinctive cribriform/cylindromatous pattern. Acinic cell carcinoma is composed primarily of serous acini. Polymorphous adenocarcinoma shows architectural diversity but lacks the MEC cellular combination. The floor-of-mouth location is also consistent with minor salivary gland MEC. The diagnosis is histopathologically definitive.
Reference: Royal College of Surgeons of England & peer-reviewed literature: Discordance between fine-needle aspiration cytology and histopathology in patients with mucoepidermoid carcinoma of parotid gland. The Annals of The Royal College of Surgeons of England, 2020. https://publishing.rcseng.ac.uk/doi/10.1308/rcsann.2020.0022; Salivary mucoepidermoid carcinoma: revisited. PubMed, 2006. https://pubmed.ncbi.nlm.nih.gov/17075295/