Anti-HMGCR antibody-associated myositis without prior exposure to statins – A case report

Immune-mediated necrotising myositis (IMNM) is a specific subtype of idiopathic inflammatory myositis. The formation of anti-3-Hydroxy-3-Methylglutaryl-Co-A Reductase (HMGCR) antibodies in people exposed to statins is a rare cause of IMNM. It is much rarer for a patient who has never taken statins to have anti-HMGCR antibodies.
This case report presents a woman in her mid-30s with symmetrical proximal muscle weakness in her lower limbs and who was diagnosed with statin naïve HMGCR-associated IMNM. She had never taken statins before, but had been on aripiprazole and olanzapine sequentially for schizophrenia. She was treated with three courses of intravenous immuno-globulin, along with methotrexate, azathioprine, and prednisolone, with clinical improvement.
This case report emphasises the importance of suspecting anti-HMGCR antibody myositis in patients without exposure to statins.