Fine Needle Aspiration Cytology of Carcinoma ex Pleomorphic Adenoma of Salivary Gland - Report of five cases -

타액선의 다형성 선종에서 발견한 암종의 세침흡인 세포학적 소견 -5 예 보고-

Carcinoma ex pleomorphic adenoma(CXPA) is a rare malignant tumor of the salivary gland, fine needle aspiration cytology(FNAC) of which are rarely reported. We retrospectively reviewed FNAC of five cases of histologically proven CXPA of the salivary glands diagnosed in Seoul National University Hospital to evaluate their cytologic characteristics. Histologically, the carcinoma components were low-grade in three cases and high-grade in two cases. The cytologic diagnosis were malignancy in two cases(40%), suspicious for malignancy in one(20%), and benign(pleomorphic adenoma) in two(40%). All of the high-grade carcinomas were correctly diagnosed by FNAC, however, 2 cases of low-grade carcinomas were diagnosed as benign by FNAC. The low sensitivity in cytologic diagnosis is due to interpretative difficulties in low-grade tumors. The characteristic cytologic features of CXPA were high cellularity, necrotic, bloody, and inflammatory background, marked nuclear overlapping, coarsely granular chromatin, prominent macronucleoli, and atypical mitosis in epithelial component in addition to the typical biphasic pattern of pleomorphic adenoma consisting of epithelial cells admired with spindle-shaped cells and chondromyxoid stroma. Even though low-grade tumors show mild pleomorphism, the cytologic findings of necrotic background, moderate to high cellularity, and nuclear overlapping could lead to an accurate cytodiagnosis of CXPA.