Mucoepidermoid carcinoma - A common neoplasm at an unusual site, mimicking a benign cyst on cytology: Diagnostic pitfall!

Mucoepidermoid carcinoma (MEC) is known to be a relatively common neoplasm of the major and minor salivary glands that can secondarily involve skin. The clinical manifestations, diagnostic cytology and histopathology of MEC presenting as a clinically benign periauricular cystic nodule have been analyzed. The challenge of accurate diagnosis can be illustrated by the fact that initially, on cytology, this tumor was misdiagnosed as a benign epidermal inclusion cyst due to the presence of mucin-filled cells which were misinterpreted as cyst macrophages. This case report emphasizes the need to include parotid tumors in the differential diagnosis of all periauricular cyst-like expansions. We also briefly discuss the reasons for false-positive cytology in this case. Delay in accurate diagnosis may result in larger surgical procedures, such as radical neck dissection, that may otherwise be avoided.