Dysdiadochokinesia, Ataxia, and Anemia: A Sign of Intraluminal Malignant Mesothelioma?

An 87-year-old man presented with altered mental status and ataxia was found to have a neuron-restricted antibody in his cerebrospinal fluid, concerning for a paraneoplastic syndrome of unknown origin. He also exhibited anemia, but otherwise normal electrolytes and liver chemistries. He underwent positron emission tomography/computed tomography which revealed abdominal lymphenopathy. He then underwent push enteroscopy and was found to have a jejunal mass, biopsy proven to be malignant mesothelioma. Malignant mesothelioma is 4-5 times more prevalent in men than women. It is limited to the small bowel, and paraneoplastic syndromes are extremely rare and carry a poor prognosis. The presence of anemia with cerebellar symptoms should trigger a search for a paraneoplastic syndrome-related malignancy.