Paraneoplastic chorea: case study with autopsy confirmation.

A 67-year-old man presented with a 7-month history of insidiously progressive chorea, ataxia, and vertigo. Neurologic examination revealed deficits referable to the basal nuclei, cerebellar vermis, and vestibular nuclei. Small-cell lung cancer was diagnosed by fine-needle biopsy of a parahilar mass. After chemotherapy, the patient's chorea worsened. Anti-Hu antibodies were present in serum and cerebrospinal fluid. Microscopic examination of the brain at autopsy revealed diffuse perivascular lymphocytic infiltrates, microglial activation, and neuronophagia throughout the neuraxis, including the brainstem, cerebellum, lenticular nuclei, striatum, and cerebral cortex. Prominent loss of Purkinje cells was seen in the cerebellar vermis and hemispheres to a lesser degree. Chorea is extremely rare as a paraneoplastic manifestation of cancer. The florid presentation and the positive findings contrasted with an unremarkable MRI of the brain. This case illustrates the preeminence of symptoms and signs over negative MRI findings in paraneoplastic encephalitis.