Abstract 17245: Statin Induced Necrotizing Autoimmune Myositis

Abstract

Description of Case: A 64 year old female with hypertension, hyperlipidemia, and type 2 diabetes presented to the emergency room for 3-4 months of progressively worsening bilateral lower extremity weakness with associated edema, but without any reports of pain. The patient had significant impairments in her daily function and now required a cane to ambulate. The patient was found to have significantly impaired strength in the bilateral lower extremities with particular involvement of the proximal thigh muscles. The patient was noted to have a markedly elevated creatine phosphokinase (CPK) to 16,000 and a moderate transaminitis. The patient underwent evaluation with an MRI which revealed several areas of bilateral necrotizing myositis. The patient’s autoimmune markers were remarkable for a positive HMG-CoA reductase antibody and a diagnosis of statin induced necrotizing autoimmune myositis was made. The patient was started on pulse dose steroids without much improvement in her weakness and functional ability. The patient was therefore started on intravenous immunoglobulin with a rapid improvement in her symptoms. The patient was discharged on long term glucocorticoid therapy with appropriate prophylactic medications. Discussion: Statin induced necrotizing autoimmune myositis (SINAM) is a very rare form of autoimmune myopathy that is characterized by rapidly progressive proximal muscle weakness along with other potential extramuscular manifestations in the setting of statin use. SINAM should be suspected in any patient on a statin, regardless of duration of treatment, who presents with proximal muscle weakness and a markedly elevated CPK, often > 1000. Treatment, like other forms of autoimmune myopathies, is often centered around immunomodulatory therapies such as high dose glucocorticoids, intravenous immunoglobulin, and long term immunosuppressants. Despite rapid initiation of aggressive treatment, severe forms of the disease have a high mortality as there may be involvement of the respiratory musculature leading to respiratory failure. Given the rarity of this condition, along with the variability in presentation related to the onset of statin therapy, diagnosis and treatment of this entity remains poorly understood.