Malignant Perineurioma

**Semantic type:** Neoplastic Process

**Definition:** A morphologic subtype of perineurioma characterized by the presence of high mitotic activity, hypercellularity, hyperchromasia, and pleomorphism.

**Synonyms:** - Malignant Peripheral Nerve Sheath Tumor with Perineurial Differentiation - Perineural MPNST - Perineurioma, malignant