We report a case of a 66-year-old female with progressive weakness and dry eyes and mouth diagnosed with LEMS based on P/Q-type voltage-gated calcium channel (VGCC) antibody positivity (0.11 nmol/L initially).  She was diagnosed with neuroendocrine tumor and treated with weekly IVIg, chemotherapy (carboplatin and etoposide) and radiation with some improvement. A year into her disease she developed Raynaud’s and tightness of her fingers, legs, back and skin compatible with scleroderma with RNA Polymerase III antibody positivity. Due to cancer progression, she was treated with ICIs (ipilimumab and nivolumab) with concomitant IVIg. Due to colitis and thyroiditis, ipilimumab was discontinued. She was stable for eight months but then developed progressive weakness, dropped head, dysphagia and increased shortness of breath. Two hertz repetitive nerve stimulation of the ulnar and spinal accessory nerve demonstrated facilitation of 223% and 128% respectively after a baseline decrement, confirming a presynaptic disorder of the neuromuscular junction with diffuse myopathic changes without fibrillation potentials on electromyography. Repeat P/Q-type-VGCC-IgG was 0.89 nmol/L; creatinine kinase levels were normal. Nivolumab was stopped, and she was treated with 3,4-diaminopyridine and weekly IVIg; corticosteroid use was limited by her scleroderma, and plasma exchange due to infection.  The patient had cancer progression and died within three weeks.