Cytological features of carcinoma ex pleomorphic adenoma of the salivary glands: A diagnostic challenge.

Carcinoma ex pleomorphic adenoma (CXPA) of the salivary glands is a relatively rare carcinoma. The detection rate of the carcinoma component in the cytological specimens is not high and may be challenging in cytological examination. The purpose of the present study was to analyze the cytological specimens of CXPA with emphasis on the detection of the carcinoma component. We reviewed the cytological characteristics of patients histopathologically diagnosed with CXPA who underwent preoperative cytological examination. Of the 10 patients enrolled in the study, 8 had tumors located in the parotid gland, and 2 in the submandibular gland. A review of the cytological specimens revealed the presence of the carcinoma component in all 10 cases and the pleomorphic adenoma (PA) component in 6 cases, although initial cytodiagnosis detected the carcinoma component in 8 cases. The cytological feature of this component was the presence of variable-sized clusters of polygonal cells with relatively rich cytoplasm and large round to oval nuclei in a necrotic background. Interestingly, carcinoma cells mixed with the PA component were also present. On histopathological analysis, 7 cases were intracapsular, and the remaining 3 cases were widely invasive CXPA. Further, 9 cases had salivary duct carcinoma as carcinoma component. In conclusion, these findings show that careful detection of the carcinoma cells, particularly within the PA component, is crucial for early detection of CXPA, and the presence of necrosis might help with the detection of the carcinoma component.