This case report details the onset of masseter muscle rigidity, elevated creatine kinase levels, and rhabdomyolysis following a sevoflurane mask induction and succinylcholine administration in a 12-year-old boy. The patient had no family or personal history of neuromuscular disease or malignant hyperthermia. Hyperkalemia, metabolic acidosis, and rhabdomyolysis occurred within 75 minutes of mass...