Ancient neurilemmoma: a pitfall in the cytologic diagnosis of soft-tissue tumors.

A case of ancient neurilemmoma (Schwannoma) is presented that, owing to a severe cell pleomorphism, was falsely interpreted as a malignant spindle-cell sarcoma by fine-needle aspiration cytology. Cytological features of the tumor are given together with its histopathology and electron microscopy findings. The usefulness of electron microscopy on material obtained by fine-needle aspiration biopsies in the diagnosis of soft-tissue tumors is discussed.