Accessory parotid gland carcinoma ex pleomorphic adenoma. Case study diagnosed by fine needle aspiration

The accessory parotid gland is salivary tissue separated from the main parotid gland and lying on masseter muscle. It has secondary duct emptying into the Stensen's duct. The accessory parotid gland exists in 21-61% of individuals. However, the appearance of an accessory parotid tumor is rare, with a reported frequency of 1-7.7% of all parotid gland tumors. Carcinoma ex pleomorphic adenoma arises from a pre-existing benign mixed tumor. Most of these tumors will have malignant epithelial component, but not malignant stromal component. Reports of Fine Needle Aspiration Cytological (FNAC) diagnosis of malignant mixed tumor are uncommon and have been limited to cases arising in the parotid. We report a case of carcinoma ex pleomorphic adenoma of the accessory lobe of the parotid, and address the cytopathology features and pitfalls of this condition.

A 73 aged female presented with a right nontender midcheek mass. The lesion had been present 18 months, with a recent increase in size. FNA was performed and the smears demonstrated features indicative of pleomorphic adenoma admixed with findings indicative of a poorly differentiated carcinoma.

FNAC can accurately diagnose carcinoma ex pleomorphic adenoma when strongly fixed requirements are implemented.