Malignant Solitary Fibrous Tumor

**Semantic type:** Neoplastic Process

**Definition:** A malignant neoplasm of probable fibroblastic derivation characterized by the presence of atypical round to spindle-shaped cells, increased cellularity, necrotic change, and high mitotic activity.

**Synonyms:** - Malignant Hemangiopericytoma - Solitary fibrous tumor, malignant