Neuropathy, Encephalopathy, Lambert-Eaton Myasthenic Syndrome and Myasthenia Gravis in a Non-Small Cell Neuroendocrine Tumor of the Lung - An Interesting Paraneoplastic Syndrome: Case Report and Review of Literature. (NELM Syndrome) (P04.094)

Abstract

Objective: To report a case of Neuropathy, Encephalopathy, Myasthenia Gravis and Lambert Eaton Myasthenic Syndrome in a patient with neuroendocrine lung cancer. Background Case reports of combined Myasthenia Gravis(MG) and Lambert-Eaton Myasthenic Syndrome(LEMS) have been reported with small cell lung cancer but never been reported in Large Cell NeuroEndocrine Cancer(LCNEC) in English literature. We describe the first case of MG, LEMS and demyelinating neuropathy in a patient with LCNEC of lung and response to intravenous immunoglobulin (IVIG) treatment. Design/Methods: case report and review of literature. Results: A 64-year-female with LCNEC(stage-1A) status post wedge resection presented with one week history of encephalopathy, diplopia, generalized weakness and paresthesia. She had autonomic instability reflected by wide fluctuation in her blood pressure. Examination showed external ophthalmoplegia, facial diplegia and proximal 2/5, distal 4/5 strength with areflexia. She was intubated secondary to neuromuscular weakness. EEG showed moderate encephalopathy. MRI of brain and cerebrospinal fluid analysis were unremarkable. Electrophysiological studies revealed severe sensorimotor demyelinating polyneuropathy. Repetitive nerve stimulation showed decremental response of > 20%. She also had positive acetylcholine receptor binding antibody and voltage gated calcium channel antibody. An extensive paraneoplastic panel was negative. Anti-Gq1b antibody was negative. Immunoperoxidase staining of lung biopsy was positive for CD-15, TTF-1, CK-7 and CAM 6.2. Patient received 2 courses of IVIG 2 gm/ kg with rapid recovery. Follow- up showed mild right upper extremity weakness and ataxia. She did not have any recurrence of symptoms in a 2 year follow- up. Conclusions: This is an unusual paraneoplastic manifestation of LCNEC lung cancer where patient presented with features of MG, LEMS and demyelinating neuropathy at the same time with very good response to IVIG. A combination of encephalopathy, ophthalmoplegia, areflexia and demyelinating neuropathy also suggests Bickerstaff Encephalitis(BE) despite negative anti-Gq1b antibody(32% negative anti-Gq1b antibody in BE). Multiple antibodies targeting different receptors may underlie pathology. Disclosure: Dr. Neelam has nothing to disclose. Dr. Lim has nothing to disclose. Dr. Singh has nothing to disclose.