Non-traumatic gas gangrene presenting as left buttock and thigh pain in a patient with metastatic non-small cell lung cancer.

We report a case of Clostridium septicum myonecrosis in a patient with metastatic non-small cell lung cancer receiving palliative chemotherapy. This is a rare but important differential diagnosis in patients with known malignancy presenting with acute pain. It is critical that the diagnosis is considered and confirmed promptly due to rapid deterioration and a potentially fatal outcome in the absence of aggressive treatment.