Cytomorphological features of salivary duct carcinoma ex pleomorphic adenoma: Diagnosis by fine-needle aspiration biopsy with histologic correlation

Abstract

We report a case of salivary duct carcinoma arising from a pleomorphic adenoma (ex pleomorphic adenoma) in a parotid salivary gland of a 70-yr-old man. Fine-needle aspiration biopsy showed two distinct subsets of cells. There was the typical biphasic pattern of pleomorphic adenoma consisting of bland epithelial cells admixed with uniform spindle-shaped cells and chondromyxoid stroma. In addition, there were features of salivary duct carcinoma best demonstrated by necrosis and the presence of large polygonal cells arranged either singly or in rosettes, clusters or sheets reminiscent of ductal carcinoma of the breast. This case illustrates that the presence of background large polygonal cells and necrosis in an otherwise typical pleomorphic adenoma may suggest the diagnosis of a high-grade carcinoma, namely salivary duct carcinoma, which portends poor prognosis and requires aggressive treatment. Differential diagnosis from other carcinomas known to arise in pleomorphic adenoma is discussed.