SHM Converge Scientific Abstract ePoster Gallery-Stubborn CPK Elevation

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A 55-year-old woman with hyperlipidemia and hypothyroidism developed one month of progressive proximal muscle weakness in her arms and legs, along with a 10-pound unintentional weight loss. Eight months earlier, she had mild transaminase elevations while taking atorvastatin, which was stopped, but her liver enzymes continued to rise. At presentation, she had severe weakness (3/5 strength in all extremities), a creatine phosphokinase (CPK) level greater than 15,000 U/L, positive ANA and SSA antibodies, and a markedly elevated anti-HMG-CoA reductase IgG level. MRI showed muscle edema, and biopsy demonstrated myonecrosis with myophagocytosis and minimal lymphocytic inflammation.<br /><br />She was diagnosed with anti-HMGCR immune-mediated necrotizing myopathy (IMNM), a subtype of necrotizing myopathy that can occur in statin-exposed or statin-naïve patients but is classically associated with statin use. IMNM typically presents with subacute proximal muscle weakness and very high CK levels, and may include pharyngeal involvement causing hoarseness or dyspnea. Muscle biopsy usually shows necrosis with little inflammatory infiltrate.<br /><br />The patient was treated with two doses of IVIG and discharged on a prednisone taper plus twice-monthly IVIG infusions with rheumatology follow-up. Statins are contraindicated in statin-associated IMNM. Treatment generally begins with glucocorticoids and IVIG, with other immunosuppressants used in less severe cases or if needed. Monitoring CK, CBC, and CMP is important, and MRI can help assess muscle edema.<br /><br />This case highlights that persistent, marked CPK elevation and proximal weakness in a patient with prior statin exposure should prompt evaluation for statin-associated IMNM, which is not responsive to fluids alone and requires immunosuppressive therapy.

Asset Subtitle

Mitchell T. Wong

Meta Tag

Author List Alan Moazzam, Chelsey Smith, Kenneth Kalunian, Lobna Shahatto, Mikolaj Sulikowski, Mitchell T. Wong, Roel Sanchez Baez, Vanessa Goodwill

Category Clinical Vignettes

Concept Statin-induced necrotizing autoimmune myopathy

Concept Anti-HMGCR Antibody

Concept Proximal Muscle Weakness

Concept Creatine Kinase

Concept Corticosteroid

Distinguished Non-Finalist

Presenter Organization UC San Diego School of Medicine

Presenting Author Mitchell T. Wong

Track Adult

Keywords

anti-HMGCR

immune-mediated necrotizing myopathy

statin-associated myopathy

proximal muscle weakness

elevated CPK

myonecrosis

muscle biopsy

intravenous immunoglobulin

prednisone taper

statin exposure

Statin-induced necrotizing autoimmune myopathy

Anti-HMGCR Antibody

Proximal Muscle Weakness

Creatine Kinase

Corticosteroid