Paraneoplastic Cerebellar Degeneration Associated with Noncutaneous Merkel Cell Carcinoma

OBJECTIVE: To report a case of paraneoplastic cerebellar ataxia including diagnosis, treatment and clinical course. BACKGROUND: Paraneoplastic cerebellar degeneration is a rare condition often associated with small cell carcinoma of the lung, breast and gynecological cancers and Hodgkin’s disease. We report a case of paraneoplastic cerebellar ataxia secondary to anti-voltage-gated calcium channel autoantibodies associated with non-cutaneous metastatic Merkel cell lymphoma. DESIGN/METHODS: Case report RESULTS: A 50-year-old male developed acute ataxia and vertigo two weeks after an upper respiratory infection. His basic serologies and neuroimaging were unremarkable. His CSF demonstrated a lymphocytic leukocytosis with normal protein and glucose. His exam was notable for pure cerebellar dysfunction, including dysarthria, truncal and appendicular ataxia. His CT chest, abdomen, and pelvis were unremarkable. He was presumed to have a post-infectious cerebellitis and given IV steroids with mild improvement. Two months later, his neurologic exam deteriorated. A paraneoplastic panel showed voltage-gated calcium channel antibodies. Antibodies to Hu, Yo, Ri, and CAR were negative. Electrophysiologic studies did not show LEMS. A PET scan revealed hypermetabolic lesions in his descending colon and left inguinal lymph nodes. Colonoscopy showed an adenomatous polyp and excisional biopsy of the inguinal node revealed high-grade carcinoma; immunostaining was consistent with Merkel cell tumor. Lymphadenectomy demonstrated involvement of 1/14 nodes and he was diagnosed with metastatic Merkel cell carcinoma. His dermatological exam was unremarkable. He did not improve after three rounds of IVIG. A repeat CT and colonoscopy at three months were unremarkable. Monthly Rituxan was added to IVIG. He demonstrated progressive improvement in ataxia after two doses. CONCLUSIONS: This case shows that Merkel cell tumors may be associated with voltage-gated calcium channel autoantibodies, which may be associated with paraneoplastic cerebellar degeneration. Abrupt onset of cerebellar symptoms warrants a careful evaluation for malignancy. Testing for a panel of autoantibodies may assist with diagnosis, and may prompt surveillance for particular tumors. Treatment with tumor resection and Rituximab may improve symptoms. Study Supported by: None Disclosure: Dr. Zhang has nothing to disclose. Dr. Lancaster has nothing to disclose.