What happened, in summary

A 57-year-old man presented with shortness of breath, generalized weakness, difficulty walking and swallowing, and extensive skin changes. A lung mass and enlarged lymph nodes were found on chest imaging, and biopsy confirmed small cell lung cancer. Muscle testing and biopsy supported dermatomyositis, with positive anti-TIF1-gamma testing pointing to a cancer-associated paraneoplastic syndrome. He started carboplatin, etoposide, and atezolizumab for the lung cancer and received steroids for the dermatomyositis. His muscle-enzyme levels initially fell, but he then developed sudden, severe skin exfoliation and his overall condition deteriorated. Despite antibiotics and close monitoring, he died 3 weeks after chemotherapy began. Specialist review considered the severe skin reaction most consistent with a life-threatening immune-related adverse event, with the damaged skin potentially contributing to infection and sepsis. His death was not attributed to documented cancer progression.