pilocytic astrocytoma
Pronunciation: pie-loh-SIT-ik
A WHO grade I astrocytic tumor characterized by bipolar cells with long hair-like processes.
Full Definition
Pilocytic astrocytoma is a benign WHO grade I astrocytic tumor that primarily affects children and young adults. The tumor is characterized by a biphasic pattern with compact areas containing Rosenthal fibers alternating with loose microcystic areas containing eosinophilic granular bodies. The constituent cells are bipolar with long, hair-like (pilocytic) processes. These tumors most commonly arise in the cerebellum, but can also occur in the hypothalamus, optic pathways, and brainstem. Pilocytic astrocytomas have an excellent prognosis following complete surgical resection, with minimal risk of malignant transformation. Some cases, particularly those in the optic pathway, are associated with neurofibromatosis type 1.
Usage
Usage note: Note biphasic pattern and association with NF1 in optic pathway cases.
In Context
- "The cerebellar tumor was diagnosed as pilocytic astrocytoma with characteristic Rosenthal fibers." — Pediatric brain tumor report
- "Pilocytic astrocytoma showed the typical biphasic architecture with microcysts." — Surgical pathology consultation