Malignant Cutaneous Neoplasms with Peripheral Nerve Differentiation

Abstract

Malignant peripheral nerve sheath tumor (MPNST) of the skin is a rare superficial sarcoma, capable of locally destructive growth and systemic metastasis. By definition, MPNST arises from a preexisting peripheral nerve sheath tumor or a nerve de novo. In the former circumstance, nearly all arise from a neurofibroma with a high association with the plexiform variant. Rare deeper variants of MPNST with epithelioid cytology may arise from schwannoma; however, this has not been well established in cutaneous forms. MPNST shows evidence of schwannian differentiation by immunohistochemical or ultrastructural methods. Rare forms with perineurial differentiation (malignant perineurioma) are described in soft tissues but so far not in the skin.