pilocytic astrocytoma
Pronunciation: pie-loh-SIT-ik as-tro-sy-TOH-mah
A benign, WHO grade I astrocytic tumor characterized by bipolar cells with long hair-like processes, commonly occurring in children.
Full Definition
Pilocytic astrocytoma is a slow-growing, benign astrocytic tumor classified as WHO grade I. It is characterized by a bipolar cell population with long, hair-like (pilocytic) processes and a biphasic pattern of compact and loose areas. Rosenthal fibers and eosinophilic granular bodies are frequently present. These tumors most commonly arise in the cerebellum, optic pathway, and hypothalamus in children and young adults. Despite their infiltrative appearance on imaging, pilocytic astrocytomas have a favorable prognosis with complete surgical resection often being curative. They may be associated with neurofibromatosis type 1 when occurring in the optic pathway.
Usage
Usage note: Grade I tumor with excellent prognosis; distinguish from diffuse astrocytomas which have infiltrative growth pattern.
In Context
- "The cerebellar tumor showed characteristic pilocytic processes and Rosenthal fibers consistent with pilocytic astrocytoma." — Pediatric neuropathology report
- "Complete resection of the pilocytic astrocytoma was achieved with excellent long-term prognosis expected." — Surgical pathology report