Fine-needle aspiration cytology of alveolar soft-part sarcoma.

Alveolar soft-part sarcoma (ASPS) is a rare soft-tissue tumor. Few cases have been reported in the aspiration cytology literature. We discuss the fine-needle aspiration (FNA) cytologic features of ASPS in four patients. The smears were characterized by single cells and clusters of cells associated with thin-walled vasculature, resulting in a distinct pseudoalveolar pattern. The cells had abundant granular cytoplasm and large round nuclei with prominent central nucleoli. Binucleated and occasional multinucleated cells were present. Numerous stripped tumor nuclei were a consistent feature. Periodic acid-Schiff (PAS)-positive diastase-resistant granules were demonstrable within the intact and fragmented cytoplasm. Electron microscopy of aspirated material identified granules and crystals with the characteristic lattice pattern. To conclude, the FNA cytologic features of ASPS are characteristic. Confirmation by special stains and electron microscopy of FNA material is possible. The differential diagnostic considerations include renal cell carcinoma, paraganglioma, granular cell tumor, clear cell sarcoma, and epithelioid sarcoma.