Spontaneous Development of Immune-Mediated Necrotizing Myopathy (IMNM) After Chronic Use of Statins: A Case Report

Statin medications, in addition to lifestyle modifications, have been the regimen of choice for addressing dyslipidemia in the general population. Its widespread use has been justified by increasing evidence that hyperlipidemia is a strong risk factor for the development of atherosclerotic disease resulting in myocardial infarction and other cardiovascular events. Unfortunately, this medication is not tolerated by some patients as it causes uncomfortable side effects such as myalgias, arthralgias, and headaches to name a few.  On rare occasions, some patients may develop immunity against the medication itself resulting in a condition known as immune-mediated necrotizing myopathy (IMNM). In such instances, patients carry antibodies against 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) or signal recognition particle (SRP). A small subset of patients may develop IMNM even in the absence of these two antibodies and they are termed seronegative. In this care report, we review the case of a 55-year-old Hispanic male with a history of Hashimoto's thyroiditis and hyperlipidemia who presented to an outpatient rheumatology office for severe proximal muscle weakness after being asymptomatic on rosuvastatin for over 20 years. The patient was stabilized with high-dose steroids and was subsequently given a regimen of mycophenolate and intravenous immunoglobulin (IVIG). He was able to regain approximately 75%-80% of his baseline muscle strength.