Mucoepidermoid carcinoma of salivary gland: Limitations and pitfalls on FNA

Mucoepidermoid Carcinoma (MEC) is the most common malignant neoplasm of salivary gland origin. However, its morphologic heterogeneity poses difficulty in interpretation. In the present series we discuss the morphologic features of MEC, limitations and pitfalls in its diagnosis on Fine Needle Aspiration Cytology (FNAC). Fourteen cases of suspected MEC were evaluated cytologically followed by histopathological examination for confirmation. A definite cytological diagnosis was rendered in nine cases; three of the remaining five were underdiagnosed as abscess, pleomorphic adenoma and mucus cyst. Of the remaining two cases, one case each of sebaceous carcinoma and sialadenitis was mislabeled as MEC on cytology. A satisfactory aspirate composed of intermediate cells, mucin secreting cells and squamous cells in a mucinous background may not be obtained in all cases of low grade MEC. High grade MEC can be classified as squamous cell carcinoma. Hence, awareness of confounding factors with clinicopathologic correlation and judicious use of frozen section can help in minimizing errors.