Perineurioma of the finger: case report of a rare peripheral nerve sheath neoplasm of pure perineurial cell lineage.

A 1.9-cm extraneural soft tissue tumor located on the palmar aspect of the index finger of a 50-year-old woman was excised. Depicting many histopathologic patterns and a full range of cellularity, the tumor was exclusively composed of epithelial membrane antigen/vimentin-positive and S-100 protein/Leu-7-negative neoplastic cells of perineurial lineage. Soft tissue (extraneural) perineurioma, a rare variant of benign peripheral nerve sheath tumor, should be included in the differential diagnosis of tumor and tumor-like conditions affecting soft parts of the hand.