FINE-NEEDLE ASPIRATION OF EPITHELIOID MALIGNANT PERIPHERAL-NERVE SHEATH TUMOR (EPITHELIOID MALIGNANT SCHWANNOMA)

The epithelioid variant of malignant peripheral nerve sheath tumor (MP NST), also known as malignant epithelioid schwannoma, is a relatively rare and recently characterized clinicopathologic entity. The epitheli oid variant of MPNST shares many clinical features with conventional M PNST but is characterized by different histologic and cytologic featur es. These include a distinctive nesting pattern and an abundance of cy toplasm not seen in histology of conventional nerve sheath tumors. Cyt ologically, the epitheliod variant shows a propensity to cellular disc ohesiveness and a plasmacytoid or epitheliod appearance that is in con tradistinction to the spindled appearance of the usual MPNST. Herein, we report our experience with fine-needle aspiration (FNA) of two epit helioid malignant schwannomas and discuss the FNA cytologic differenti al diagnosis. (C) 1997 Wiley-Liss, Inc.