Statin-Associated Immune-Mediated Necrotizing Myopathy: A Case Report

Case Diagnosis: 58-year-old male with a past medical history of hyperlipidemia, hypertension, hypothyroidism, sleep apnea presenting with gradually worsening proximal weakness, diagnosed with statin-associated immune-mediated necrotizing myopathy.

Case Description or Program Description: 58-year-old male presented to the hospital as a direct admit from his outpatient neurology office. He began with mild weakness in 11/2024 in his lower extremities. He was admitted 01/21/25-1/23/25 due to weakness now involving his upper extremities, as well as concern for rhabdomyolysis given elevated CK levels. After he was medically stable, antibody panels were sent, and he was instructed to follow up with neurology as an outpatient on discharge. HMG-CoA reductase antibodies were positive, and he had profound weakness at the outpatient visit. He was directly admitted for IVIG treatment. He was given IVIG, IV steroids and daily prednisone thereafter during his hospital stay.

Setting: Post-acute rehabilitation hospital

Assessment/Results: He was admitted to a post acute rehab hospital due to his significant change from baseline functional status. After 13 days in inpatient rehabilitation, the patient was evaluated by neurology and readmitted to the hospital for another round of IVIG. Neurology recommends IVIG treatments every 2 weeks with continuation of 60mg prednisone daily. If symptoms do not improve, recommend rituximab or azacitidine therapy.

Discussion (relevance): Diagnosis of statin-associated immune-mediated necrotizing myopathy can be difficult, especially considering the gradual onset of vague symptoms potentially presenting years after statin initiation. It is known that early intervention with medical therapies including IVIG and IV steroids are vital to preserving and improving muscle function, so swift diagnosis is key for maximal patient recovery.

Conclusions: Statin-associated immune-mediated necrotizing myopathy is a rare complication of statin use, but should be considered in all statin users presenting with proximal weakness affecting functioning regardless of statin onset time. Treating this diagnosis requires a multi-disciplinary approach to facilitate restoring function and quality of life.