A cystic mass with strongly enhancing mural nodule is present in the right posterior frontal region, without significant mass effect or surrounding edema.
pilocytic astrocytoma, pleomorphic xanthoastrocytoma, less likely hemangioblastoma or ganglioglioma
Pilocytic astrocytomas are low grade glial neoplasms, 60% of which arise in the posterior fossa. 50% have a cyst/mural nodule appearance. Prognosis is excellent, with 25 yr survival rate in excess of 90% if resection is complete. Calcification is uncommon, seen in up to 25%. The cystic portion contains proteinaceous fluid and no capsule. Surrounding edema is rare. The mural nodule is usually iso-hypo T1, hyper T2. A solid, centrally necrotic subtype represents the other 50% of PA, which has a more guarded prognosis.
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