Chronic Onset Form of Anti-HMG-CoA Reductase Myopathy

We report a case of anti-HMGCR myopathy mimicking limb-girdle muscular dystrophy in a 27-year-old male patient with no history of statin intake and presenting with a chronic onset form over 3 years. Treatment with prednisone and methotrexate was initiated with an insufficient response, so intravenous immunoglobulin was added. One year after initial treatment was started, as levels of creatine kinase (CK) were >1000 U/l, treatment with rituximab was added. Despite a 3-year delay before treatment, muscle strength improved even though CK levels remain elevated. LEARNING POINTS: We describe a case of anti-HMGCR myopathy mimicking limb-girdle muscular dystrophy, which resulted in delayed diagnosis and management. The patient’s muscular strength improved but creatine kinase levels remain elevated despite comprehensive treatment.