Internal Medicine Jamaica Hospital Bronx, New York, United States
Clinical Scenario or Case: A 65-year-old male with a history of hypertension, diabetes, and hyperlipidemia presented with several weeks of progressive bilateral lower extremity weakness, culminating in functional decline and inability to ambulate. Initial imaging ruled out acute infarct, spinal cord compression, and metabolic derangements. Given proximal greater than distal weakness and elevated CK levels, further neuromuscular workup was pursued. Muscle biopsy confirmed necrotizing myopathy. A myositis panel revealed anti-HMG-CoA reductase antibodies, consistent with immune-mediated necrotizing myopathy (IMNM).
Evidence/Literature Review: IMNM is a rare but serious inflammatory myopathy often associated with statin exposure. Anti-HMGCR antibodies are highly specific markers, and symptoms may persist despite statin discontinuation. Studies show that IVIG, corticosteroids, and immunosuppressants are effective treatments. According to Mammen et al. up to 50% of patients may experience incomplete recovery, especially without early intervention. The American College of Rheumatology guidelines highlight the need for early and aggressive immunosuppression in autoimmune necrotizing myopathies to prevent long-term disability.
Unique Aspects of Case: This case demonstrates an uncommon presentation where diagnosis was delayed due to atypical symptom distribution and confounding imaging. Despite discontinuing statin therapy, the patient’s weakness progressed, emphasizing the autoimmune nature of the condition. Biopsy-confirmed IMNM, in conjunction with a positive anti-HMGCR antibody, established the diagnosis and guided immunosuppressive therapy. The patient required IVIG, corticosteroids, and mycophenolate with partial clinical improvement.
Recommendations/Conclusions: Statin-associated autoimmune necrotizing myopathy (IMNM) is an underrecognized yet disabling condition that may progress despite discontinuation of the offending agent. This case underscores the importance of early recognition, comprehensive diagnostic evaluation—including anti-HMGCR antibody testing—and timely initiation of immunosuppressive therapy. A multidisciplinary approach and long-term follow-up are critical for improving functional recovery and reducing morbidity. Clinicians should be vigilant when evaluating persistent myopathy in statin-exposed patients, as delays in diagnosis and treatment may lead to irreversible muscle damage and prolonged disability. Early intervention is key to altering the disease trajectory.
