Pilocytic Astrocytoma in adults
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Less common in adults (0.5 per million vs 8.3 per million in children) Mean age of 50. Median age of 45.
Slight predilection for the supratentorial space (55% vs 67% in the cerebellum in children) Infratentorial lesions have a much shorter clinical history.
Associated with NF-1. Up to 90% of patients present with HAs; truncal ataxia (cerebellar lesions); rarely cranial nerve deficits.
MRI: mixed intensities on T1/2, often cystic, marked enhancement, little edema, rarely hemorrhage.
Biphasic pattern: compact bipolar cells with Rosenthal fibers and loosely textured multipolar cells with eosinophilic granular bodies and microcysts.
Treatment and prognosis
Total resection is treatment of choice. Radiation/chemotherapy for lesions of the optic pathway, thalamic, and brainstem lesions. Similar in clinical behavior to pediatric group with excellent prognosis (up to 100% at 5 yrs and 96% at 10 yrs). Very rarely undergo malignant degeneration.