High Grade Astrocytoma with Piloid Features

**Semantic type:** Neoplastic Process

**Definition:** An astrocytoma characterized by high-grade piloid and/or glioblastoma-like histological features. It may occur anywhere in the central nervous system but most often arises in the posterior fossa. Alterations in the following three pathways are responsible for the pathogenesis of this tumor: MAPK pathway, retinoblastoma tumor suppressor protein cell-cycle pathway, and telomere maintenance pathway.

**Synonyms:** - Anaplastic Astrocytoma with Piloid Features - Anaplastic Pilocytic Astrocytoma - High-Grade Astrocytoma with Piloid Features