Rinsho Shinkeigaku (Clinical Neurology)

Case Report

Anti-mitochondrial M2 antibody-positive myositis preceded by heart failure and cardiac conduction disturbance. A case report

Keitaro Ogaki, M.D.1), Hiroaki Fujita, M.D., Ph.D.1), Norito Kokubun, M.D., Ph.D.1), Mai Hamaguchi, M.D.1), Ichizo Nishino, M.D., Ph.D.2)3) and Keisuke Suzuki, M.D., Ph.D.1)

1) Department of Neurology, Dokkyo Medical University, Tochigi
2) Department of Neuromuscular Research, National Institute of Neurology, National Center of Neurology and Psychiatry, Tokyo
3) Department of Clinical Genome Analysis, Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo

A 69-year-old man visited our hospital complaining of fatigue in the lower extremities while walking. The patient had a two-year history of congestive heart failure and received a permanent artificial pacemaker implantation for sick sinus syndrome. Physical examination revealed proximal muscle weakness and exaggerated lumbar lordosis. Serum creatine kinase level was 1,455 U/l. The atrophies of the paraspinal muscles at thoracic to lumbar spine levels, rectus abdominis and soleus muscles were detected on computed tomography. Muscle biopsy showed mild to moderate variability in muscle fiber size with regenerating and necrotic muscle fibers. Mononuclear cell infiltration was not found. HLA-ABC expression was minimum. After anti-mitochondrial M2 antibody was detected, administration of oral prednisolone resulted in improvements in muscle strength and serum creatine kinase level. Based on the clinical course, examination and clinical findings, the patient was diagnosed as anti-mitochondrial M2 antibody positive myositis. Anti-mitochondrial M2 positive myositis is not only difficult to diagnose by muscle biopsy, but can also be preceded or complicated by fatal cardiac complications.
Full Text of this Article in Japanese PDF (1756K)

(CLINICA NEUROL, 62: 135−139, 2022)
key words: anti-mitochondrial M2 positive myositis, cardiac conduction disturbance, heart failure, trunk muscle, soleus muscle

(Received: 19-May-21)