Presentation
Ataxia, dystonia and headache of long duration. CT was unremarkable.
Patient Data
A large ill-defined infiltrative lesion is seen involving almost the entire right cerebellar hemisphere, with mass effect on the fourth ventricle and herniation through the foramen magnum. The lesion extends through and widens the middle cerebellar peduncle to involve the right pons. This lesion is isointense on T1WI and hyperintense on T2WI/FLAIR and shows mild diffusion restriction. The postcontrast study reveals a moderately enhancing nodule at the periphery of the right cerebellum; however, most of the lesion does not enhance.
Case Discussion
Microscopy: diffuse astrocytoma (fibrillary type) degenerated into anaplastic astrocytoma (WHO grade III).
Diffuse astrocytomas are classified as WHO grade II tumors, with a median survival of 6-10 years, yet with an intrinsic tendency towards malignant transformation into anaplastic astrocytoma (WHO grade III) or glioblastoma multiforme (WHO grade IV).
Differential considerations for this case include ischemia, cerebellitis and tumefactive demyelination.
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