An Anti-PM/Scl-75 Antibody-positive Japanese Woman Who Developed Inflammatory Myopathy

Abstract

A 69-year-old Japanese woman presented with mild muscle weakness of the neck and symmetrical proximal parts of the upper and lower limbs. Laboratory tests, needle electromyography, and a muscle biopsy revealed inflammatory myopathy with an apparent clinical classification of polymyositis and positive findings for anti-PM/Scl-75 antibody. This antibody is rare among Japanese populations, and most Japanese patients with the antibody are not classified with the inflammatory myopathy seen in polymyositis. The muscle biopsy also showed marked necrotic and regenerative fibers. We need to collectively investigate patients with the potential to develop this disease, and to identify any unique characteristics for Asian populations, including Japanese.

Interstitial Lung Disease Is a Major Characteristic of Patients Who Test Positive for Anti-PM/Scl Antibody

“…The frequency of anti-PM/Scl also appears to vary between different ethnic groups. Most patients with anti-PM/Scl antibodies were double positive for anti-PM/Scl-75 and anti-PM/Scl-100 ( 6 , 10 ). De Lorenzo et al reported that among patients with anti-PM/Scl autoantibodies, 63% were positive for both anti-PM/Scl-75 and anti-PM/Scl-100, 20% were positive only for anti-PM/Scl-100, and 17% were positive only for anti-PM/Scl-75 ( 6 ).…”

“…De Lorenzo et al reported that among patients with anti-PM/Scl autoantibodies, 63% were positive for both anti-PM/Scl-75 and anti-PM/Scl-100, 20% were positive only for anti-PM/Scl-100, and 17% were positive only for anti-PM/Scl-75 ( 6 ). Recently, 11 Japanese patients with anti-PM/Scl antibody were summarized by Nakamura et al, 6 patients were positive for both anti-PM/Scl-75 and anti-PM/Scl-100, 4 only for anti-PM/Scl-100, and one positive for anti-PM/Scl-75 alone ( 10 ). Contrast to previous studies, this study showed half of the patients with anti-PM/Scl-75 along, a third of patients were positive only for anti-PM/Scl-100, and very few patients with positive double antibody.…”

A case of inflammatory myopathy with anti‐PM/Scl antibodies myopathologically presenting as polymyositis with mitochondrial pathology

“…To our knowledge, only 11 cases of Japanese autoimmune patients with anti‐PM/Scl antibodies have been reported 1,2,8 . Among them, four cases of DM 1,8 and one of inflammatory myopathy with an apparent clinical classification of PM myopathologically presenting as immune‐mediated necrotizing myopathy 2 were reported, but no case of PM‐Mito was included.…”

“…Anti‐PM/Scl antibodies are mainly associated with polymyositis (PM)/systemic sclerosis (SSc) overlap syndrome and are also identified in other autoimmune diseases such as PM, dermatomyositis (DM), SSc, and Sjögren's syndrome 1 . A detailed myopathological analysis of inflammatory myopathy with anti‐PM/Scl antibodies has been rarely reported, 2,3 and its myopathological features are yet to be definitively confirmed.…”

“…To our knowledge, only 11 cases of Japanese autoimmune patients with anti-PM/Scl antibodies have been reported 1,2,8. Among them, four cases of DM1,8 and one of inflammatory myopathy with an apparent clinical classification of PM myopathologically presenting as immune-mediated necrotizing myopathy2 were reported, but no case of PM-Mito was included. Because SSc and other systemic autoimmune diseases were not detected, we believe that the present study is the first report of a case of the clinical development of isolated muscular symptoms and myopathological presentation as PM-Mito among the inflammatory myopathies with anti-PM/Scl antibodies.…”