Rhabdomyolysis observed at forensic autopsy: a series of 52 cases

Rhabdomyolysis is characterized by skeletal muscle injury resulting in the release of intracellular proteins (such as myoglobin) and electrolytes into the blood circulation, which cause acute kidney injury, myoglobinuria and electrolyte imbalances. Clinical diagnosis of rhabdomyolysis is made on the basis of biochemical analysis; however, for forensic autopsies, biochemical data are often not available, and it is necessary to diagnose rhabdomyolysis via histopathological examinations. This study analyzed 52 cases with rhabdomyolysis and applied myoglobin immunohistochemistry to kidney, urine and blood samples. We found that blunt force injuries were the most common cause of rhabdomyolysis across all age groups, and drugs were the second most common cause. The drugs included ketamines, amphetamines, synthetic cathinones, entheogens, benzodiazepines, opioid analgesics, and anesthesia. Less than 60% of our cases had biochemical data, including myoglobin (92.5~416,978 ng/mL), creatine kinase (220~774,015 U/L), potassium (1.6~10.3 meq/L), calcium (2.7~29.2 mg/dL), and phosphorus (2.6~14.2 mg/dL). In the kidney tissue sections, we found that 95% of the rhabdomyolysis cases were positive for myoglobin immunohistochemistry and that 96% were associated with acute tubular necrosis. Our findings describe the features of fatal rhabdomyolysis in a large series and suggest that myoglobin immunohistochemistry can be used in post-mortem blood and urine cell blocks to detect myoglobin.