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Updated: Nov 9, 2025

Immunolabelling Myofiber Degeneration in Muscle Biopsies
Published on: December 5, 2019
An Autopsy Case of Antibody-negative Immune-mediated Necrotizing Myopathy with Severe Cardiac Involvement
Takumi Tamura1, Keisuke Miyajima2, Kazuki Watanabe3
1Division of Cardiology, Internal Medicine III, Hamamatsu University School of Medicine, Japan.
Abstract:
A 41-year-old man was admitted with a chief complaint of dyspnea. Echocardiography showed diffuse severe hypokinesis in the left ventricle. Although his heart failure improved, high creatine kinase levels persisted. A muscle biopsy of the biceps brachii showed necrotic and regenerating fibers along with positive findings for major histocompatibility complex class I and membrane attack complex. He was diagnosed with antibody-negative immune-mediated necrotizing myopathy (IMNM). Steroid therapy was started, but he died due to ventricular fibrillation. Autopsy findings revealed CD68-positive macrophages in the myocardium and quadriceps. To our knowledge, this is the first case of antibody-negative IMNM with cardiac involvement.
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