We present a 66-year-old woman with 2 months of visual hallucinations, unintentional weight loss, and short-term memory decline, whose clinical presentation and EEG supported a diagnosis of limbic encephalitis. Subsequent evaluation for a paraneoplastic etiology revealed a renal mass, which was resected and identified as clear cell renal carcinoma. The patient's clinical condition improved after resection of the mass. When patients present with incongruous subacute neuropsychiatric symptoms, clinicians should be mindful of paraneoplastic neurological disorders, as early diagnosis and treatment of malignancy may lead to symptomatic improvement.
CASE DESCRIPTIONA 66-year-old woman presented with 2 months of new visual hallucinations. She initially saw spiders on the walls; at the time of her presentation, however, she was having more vivid hallucinations, including seeing known deceased people harm her neighbors. While these visions were disturbing to her, she recognized that they were hallucinations and did not respond to them. Over the same period, her family also noticed shortterm memory decline and an unintentional weight loss of 20 pounds. Her review of systems was otherwise normal, including a lack of symptoms suggestive of depression, and she had no medical, psychiatric, or relevant family history. She did not take medicines and denied use of tobacco, alcohol, and illicit drugs.On physical examination, the patient was hemodynamically stable and had a normal cardiovascular, respiratory, abdominal, and pulmonary examination. Detailed neurological examination revealed no focal neurological deficits, including normal cranial nerves, intact and symmetric strength throughout, normal reflexes, no nystagmus, intact finger-to-nose testing, normal gait, and no dysdiadochokinesia with rapid alternating movement. She performed poorly on the Montreal Cognitive Assessment 1 , having particular difficulty with visuospatial skills, naming, and both immediate and delayed recall. Comprehensive laboratory assessment was performed and revealed normal urinalysis, complete blood count, basic metabolic panel, hepatic function panel, thyroid-stimulating hormone, free thyroxine, ammonia, folate, and vitamin B12. HIV testing and urine toxicology screen were negative. Cerebrospinal fluid (CSF) was colorless, with only one white blood cell (monocyte), one erythrocyte, glucose level of 65 mg/dL (normal range, 40-85 mg/dL), and protein level of 43 mg/dL (normal range, 15-45 mg/dL). CSF was negative for herpes simplex virus via PCR, fungal staining, and New York State Viral Encephalitis panel. CSF cytology was negative, and CSF protein electrophoresis did not identify any oligoclonal bands. Serum electrophoresis detected a distinct monoclonal band in the gamma region, but immunofixation was not performed. MRI of the brain, with and without contrast, revealed mild diffuse atrophy and subcortical hyperintensities on T2 and FLAIR imaging, findings which were nonspecific and possibly related to microvascular disease, but also potentially co...
