The fine‐needle aspiration cytology of metastatic pleomorphic dermal sarcoma

Dear Dr. Bedrossian: Undifferentiated high-grade sarcomas of the skin, which have until recently been referred to as atypical fibroxanthoma (AFX), are tumors with a characteristic clinical presentation of a superficial, ulcerating mass, usually of the head and neck region of older males, that is limited to the dermis. The recognition that lesions with many of the clinical and pathologic characteristics of AFX can also extend beyond the dermis, with variable necrosis and vascular invasion, and have a more aggressive clinical course, has resulted in a new clinicopathologic entity referred to as pleomorphic dermal sarcoma (PDS). PDS appears to occupy the middle of a spectrum of aggressive behavior between AFX and the much deeper situated undifferentiated pleomorphic sarcoma (UPS). Given the new and evolving nature of the literature regarding PDS, it is not surprising that that there are no reports of the fine-needle aspiration (FNA) cytology of PDS. We believe this is the first report of the cytologic presentation of a metastatic PDS and its histologic correlate from an 87-year-old male who presented with a rapidly enlarging ear lesion that had the typical clinical and pathologic features of an AFX with multiple recurrences and eventual regional lymph node metastases evaluated by FNA cytology. Diff-Quik and Papanicolaou stain smears showed individually scattered and loosely clustered, markedly atypical cells including multinucleated tumor giant cells, and osteoclastic cells (Figs. 1 and 2). The cytoplasm was abundant and amphophilic with occasional cells exhibiting a delicate foamy “xanthomatous” appearance. The nuclei were pleomorphic with irregular contours, coarse chromatin, and readily identifiable single and multiple nucleoli. The previously excised ear lesion demonstrated AFX-like features with invasion beyond the dermis into the subcutaneous tissues adjacent to the auricular cartilage. The cells in the excised ear lesion had similar features to the cytologic smears (Fig. 3). From a cytologic perspective, the cells of PDS present with a spectrum of morphologic findings ranging from relatively small, fusiform to spindle-shaped cells having oval nuclei to markedly enlarged, pleomorphic cells with single and multiple irregular nuclei and prominent nucleoli. The cytoplasm is typically abundant, amphophilic and sometimes delicately foamy, and xanthomatous. These cytologic features raise a differential diagnosis that is primarily centered upon PDS/AFX, UPS, sarcomatoid carcinomas, sarcomatoid melanoma, and metastasizing