Pseudotumoral hemicerebellitis with hemorrhage

Acute cerebellitis is an inflammatory syndrome occurring most commonly in young children. It is caused by a variety of insults and is usually bilateral. Pseudotumoral hemicerebellitis is an exceptionally rare unilateral presentation of acute cerebellitis mimicking a tumor. Magnetic resonance imaging (MRI) reveals a diffusely swollen cerebellar hemisphere, but with the lack of a well-defined mass, which is hyperintense in T2-weighted images and with pial enhancement in post-contrast images. It typically has a benign course with regression in follow-up scans, thus distinguishing it from a tumor. Recognizing this entity is important because erroneous diagnosis may lead to needless surgical intervention. We present a case of pseudotumoral hemicerebellitis in a 12-year-old boy with coagulopathy, with follow-up MRI depicting hemorrhage, and discuss the pathogenesis.