Kensuke Ikeda1, Madoka Mori-Yoshimura, Toshiyuki Yamamoto, Masahiro Sonoo, Shigeaki Suzuki, Yoshiyuki Kondo, Harumasa Nakamura, Kana Mitsuhashi, Meiko Hashimoto Maeda, Jun Shimizu, Yukiko K Hayashi, Ichizo Nishino, Yasushi Oya, Miho Murata. 1. *Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan; †Department of Neurology, Teikyo University School of Medicine, Tokyo, Japan; ‡Department of Neurology, Keio University School of Medicine, Tokyo, Japan; §Department of Neurology, Toranomon Hospital, Tokyo, Japan; ¶Department of Neurology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan; ‖Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan; **Department of Pathophysiology, Tokyo Medical University, Tokyo, Japan; and ††Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.
Abstract
OBJECTIVES: To report cases of chronic autoimmune necrotizing myopathy with anti-signal recognition particle antibodies (anti-SRP myopathy) initially misdiagnosed as muscular dystrophy, in particular, facioscapulohumeral muscular dystrophy (FSHD). METHODS: Medical records of patients with anti-SRP myopathy in our institution were retrospectively reviewed. RESULTS: All 6 patients were initially diagnosed with muscular dystrophy because of the long-term clinical course and lack of inflammation on biopsy; 5 were diagnosed with FSHD based on a winged scapula. However, the following features suggested an alternative diagnosis, leading to anti-SRP antibody measurement: (1) lack of family history, (2) lack of facial involvement and asymmetry, (3) prominent dysphagia, and (4) profuse spontaneous activities on needle electromyography. All patients showed improvement with immunomodulating therapy. CONCLUSIONS: Anti-SRP antibody measurement should be considered in patients diagnosed with FSHD if they present with diagnostic hallmarks of anti-SRP myopathy listed above, to avoid oversight of this potentially treatable disorder.
OBJECTIVES: To report cases of chronic autoimmune necrotizing myopathy with anti-signal recognition particle antibodies (anti-SRP myopathy) initially misdiagnosed as muscular dystrophy, in particular, facioscapulohumeral muscular dystrophy (FSHD). METHODS: Medical records of patients with anti-SRP myopathy in our institution were retrospectively reviewed. RESULTS: All 6 patients were initially diagnosed with muscular dystrophy because of the long-term clinical course and lack of inflammation on biopsy; 5 were diagnosed with FSHD based on a winged scapula. However, the following features suggested an alternative diagnosis, leading to anti-SRP antibody measurement: (1) lack of family history, (2) lack of facial involvement and asymmetry, (3) prominent dysphagia, and (4) profuse spontaneous activities on needle electromyography. All patients showed improvement with immunomodulating therapy. CONCLUSIONS: Anti-SRP antibody measurement should be considered in patients diagnosed with FSHD if they present with diagnostic hallmarks of anti-SRP myopathy listed above, to avoid oversight of this potentially treatable disorder.