A Case of Statin-Induced Necrotizing Autoimmune Myopathy

Statins, commonly used for hyperlipidemia and more importantly having proven efficacy in lowering cardiovascular risk, are a very popular class of medications. Side effects are usually mild, and the class as a whole is generally well-tolerated by patients. However, one rare and more serious side effect is statin-induced autoimmune necrotizing myopathy. A 65-year-old woman with a past medical history of hyperlipidemia on atorvastatin for four years, type 2 diabetes, sciatica, and a prior history of endometrial cancer, presented to the emergency department due to proximal muscle weakness worsening over 2-3 months. On labs, her aspartate transaminase (AST) and alanine transaminase (ALT) were both elevated at 344 and 244, respectively. Additionally, creatine kinase (CK) was 13,000, C-reactive protein (CRP) was 42, and aldolase was 80.4. She was antinuclear antibody (ANA) negative but found to be anti-3-hydroxy-3- methylglutaryl-coenzyme A reductase (HMGCR ab) positive. Her magnetic resonance imaging (MRI) showed significant edema in bilateral thighs. During her hospital course, she was started on prednisone, fluids, and intravenous immunoglobulin (IVIG). Once completing two days of IVIG, the patient was discharged to rehab with rheumatology follow-up. The purpose of this case is to elucidate a rare side effect of a medication despite being on it for several years and to increase awareness and attention to an adverse effect that may one day lead to stratifying patients' risk on the medication.