Central nervous system lymphoma presenting with ataxic hemiparesis: a case report.

An 81-year-old man with central nervous system (CNS) lymphoma presenting with acute, progressive ataxic hemiparesis. Computed tomography and magnetic resonance imaging localized the lesion extending from the right internal capsule to the ventrolateral aspect of rostral midbrain tegmentum. A stereotactical biopsy yielded a microscopic diagnosis of medium-sized diffuse B-cell lymphoma. Although the most frequent cause of the syndrome of ataxic hemiparesis is a lacunar type of cerebral infarction, this article emphasizes that CNS lymphoma can produce the syndrome.