Cytologic diagnostic pitfall of dermatofibrosarcoma protuberans masquerading as primary parotid tumor: a case report

We report the cytology of a rare case of dermatofibrosarcoma protuberans (DFSP) involving the parotid region. Our patient was a 55-year-old female who presented with a swelling in the right parotid region, which was clinically interpreted as a "recurrent parotid tumor." Fine needle aspiration revealed a moderate cellular yield with spindle cell component, seen discretely as well as, embedded loosely within a fibrillary magenta matrix. A few cellular spindle cell fascicles and several discrete, naked, spindly nuclei were also noted. Neoplastic cells exhibited a minimal pleomorphism with a relatively bland chromatin and inconspicuous nucleoli. A differential diagnosis of the benign spindle cell tumor/low, or intermediate grade myxoid, spindle cell sarcomas was considered. Owing to its clinical presentation simulating a parotid tumor, possibility of "spindle cell myoepithelioma" was suggested. However, histopathologic examination with immunohistochemistry showed it to be a DFSP. A precise diagnosis of DFSP is not always possible on cytology alone. Owing to its location, as well as the spindle cell morphology, DFSP occurring in the parotid region is likely to be mistaken for a spindle cell myoepithelioma, in which case, an appropriate panel of immunomarkers is required for resolving the diagnostic dilemma.