MCQ Pathology Answer 17
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Mucoepidermoid carcinoma is the most common salivary gland malignancy and makes up between 5 and 9% of all salivary gland neoplasms. It develops most commonly in the major salivary glands, most often the parotid (45-70%). The second most common site of occurrence is the palate (18%).
Microscopically, these tumors are characterized by the presence of two populations of cells—the mucus cells and the epidermoid cells, the proportion of which helps to define the grade of the tumor.
- Low-grade mucoepidermoid carcinoma is characterized by prominent cystic structures and mature cellular elements. This tumor contains proportionally more mucus cells, which may form gland-like structures, and fewer epidermoid cells.
- Intermediate-grade tumors display fewer and smaller cysts and occasional solid islands of epidermoid tumor cells. Although mucus cells are still present, there is an increasing proportion of epidermoid cells and occasional keratin pearl formation.
- The high-grade carcinomas are hypercellular, solid tumors with noticeable cellular atypia and frequent mitotic figures. These tumors will often be mistaken for a squamous cell carcinoma and the differentiation between the two can be quite difficult. Positive immunohistochemical staining for mucin indicates a high-grade mucoepidermoid carcinoma rather than a squamous cell carcinoma.
Tags: MCQ, Pathology, Salivary Gland, Neoplasms
Category: Pathology MCQs
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