[The value of muscle biopsy in rhabdomyolysis]

Objective: To analyze the diagnostic value of skeletal muscle biopsy in patients with rhabdomyolysis. Methods: Clinical and pathological data of 26 patients with rhabdomyolysis from January 2002 to December 2018 undergoing muscle biopsy were collected. Results: Eighteen males and 8 females were finally recruited with median age of 6-73 (37.3±19.6) years. The average time from onset to biopsy was 44 days (median course was 30 days). All patients had acute manifestations with muscle pain and/or weakness. Serum creatine kinase was between 1 648-92 660 U/L. Muscle biopsies showed nonspecific changes in 12 cases (a few with type 2 muscle fiber atrophy, slight deposition of lipid droplets), 10 cases with necrotizing myopathy (muscle fiber necrosis and regeneration). Toxic neurogenic damages were seen in 2 cases (type 1 and type 2 angular atrophic muscle fibers with group change), lipid storage disease in 1 case (lipid droplets deposit significantly) and idiopathic inflammatory myopathy in 1 case (muscle fiber necrosis and regeneration, with lymphocyte infiltration). The etiology of non-specific pathological changes included short-term strenuous exercise in 6 patients, poisoning in two, chronic kidney disease in one, viral infection in one, hypothyroidism in one and unknown reason in one. As to patients with necrotizing myopathy, seven were poisoning or drug-related, one with hyperthyroidism, two with unknown reason. Conclusions: Among the numerous causes of rhabdomyolysis, exercise usually links nonspecific skeletal muscle changes and poisoning or drug-related disorders are commonly associated with necrotic myopathy. Rhabdomyolysis induced by primary myopathy is rare.