perineurioma
Pronunciation: per-ih-new-ree-OH-mah
A rare benign tumor composed of perineurial cells that can occur intra- or extraneurally.
Full Definition
Perineurioma is a rare benign tumor composed exclusively of perineurial cells, the specialized cells that normally form the perineurium around peripheral nerve fascicles. These tumors can be classified as intraneural (occurring within nerves) or extraneural (soft tissue). Intraneural perineuriomas typically present as slowly progressive nerve enlargement with gradual functional loss, while extraneural variants present as soft tissue masses. Histologically, perineuriomas show spindle cells arranged in whorled patterns with characteristic long, slender cytoplasmic processes. The cells are strongly positive for EMA (epithelial membrane antigen) and claudin-1, but negative for S-100 protein, helping distinguish them from schwannomas.
Usage
Usage note: Specify intraneural vs extraneural; note EMA positivity as key feature.
In Context
- "The nerve biopsy revealed intraneural perineurioma with characteristic EMA-positive perineurial cells." — Peripheral nerve biopsy report
- "Extraneural perineurioma was confirmed by claudin-1 positivity and S-100 negativity." — Soft tissue pathology report