Altered mental status is a common chief complaint among patients who visit the emergency department. Encephalitis is one of many disease processes that can lead to altered mental status. We present a unique case of a 52-year-old man presenting in the emergency department with aggressive behavior and altered mental status. CT imaging revealed a newly-discovered renal cell cancer, as well as CSF analysis highly suggestive of anti-GAD-associated encephalitis. Patient was successfully treated with steroids and plasmapheresis to achieve significant clinical improvement. To our knowledge, this is the first reported case of anti-GAD paraneoplastic encephalitis in the setting of renal cell cancer that initially presented with aggressive behavior and altered mental status.
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