pilocytic astrocytoma
Pronunciation: /paɪloʊˈsɪtɪk/
A WHO grade I benign brain tumor most commonly occurring in children, characterized by its circumscribed growth and excellent prognosis.
Full Definition
Pilocytic astrocytoma is the most common primary brain tumor in children, representing a WHO grade I neoplasm with typically benign behavior. These tumors are characterized by their circumscribed growth pattern, biphasic histology with compact and loose areas, and the presence of Rosenthal fibers and eosinophilic granular bodies. They most commonly arise in the cerebellum, hypothalamus/optic pathway, and brainstem. BRAF alterations, particularly KIAA1549-BRAF fusion, are frequently identified. Complete surgical resection is usually curative, though tumors in eloquent locations may require observation or alternative treatments. The prognosis is excellent with near 100% survival when completely resected.
In Context
- "The cerebellar pilocytic astrocytoma was successfully resected with excellent postoperative outcome." — Surgical report
- "BRAF fusion testing confirmed the diagnosis of pilocytic astrocytoma." — Molecular pathology report