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Anti‐ PM /Scl antibody‐positive dermatomyositis in a Japanese patient: a case report and review of the literature

2017; Wiley; Volume: 20; Issue: 12 Linguagem: Inglês

10.1111/1756-185x.13019

1756-185X

Aki Kohara, Koichi Yanaba, Yoshinao Muro, Hideki Ito, Hidemi Nakagawa, Kentaro Noda, Daitaro Kurosaka,

Skin Diseases and Diabetes

Dear Editor, Anti-PM/Scl (polymoyositis/scleroderma) antibodies recognize two major components, PM/Scl100 and PM/Scl75.1 They are detected in approximately 25% of patients with overlap syndrome of PM and systemic sclerosis (SSc), 3–13% of patients with SSc, 7–8% of patients with PM, and 1–3% of patients with dermatomyositis (DM),2-4 but these data are based on European and North American patients. The frequencies of anti-PM/Scl antibodies vary by ethnicity, and the emergence of anti-PM/Scl antibodies has been considered to be very rare in the Asian population. Here, we describe a Japanese case of DM that was positive for anti-PM/Scl antibodies and review three other previously reported Japanese cases. A 64-year-old Japanese man was referred to us with a 6-month history of erythematous plaques on his hands and a 1-month history of polyarthralgia and muscle weakness. Physical examination revealed Gottron's lesions on the dorsal aspects of the hands and fingers (Fig. 1a) as well as the elbows and knees (Fig. 1b), mechanic's hands, shawl sign and facial erythema (Fig. 1c). Hyperkeratotic lesions were observed on the soles. Skin sclerosis, swollen fingers and Raynaud's phenomenon were not observed. Laboratory investigation revealed an erythrocyte sedimentation rate of 18 mm/h, C-reactive protein of 0.27 mg/dL, creatine kinase of 140 IU/L (normal range, 62–287), aldolase of 9.9 U/L (normal range, 2.1–6.1), surfactant protein-D (SP-D) of 162 ng/mL (normal range, < 110), and KL-6 of 2582 U/mL (normal range, < 500). Antinuclear antibody test was positive at 1:160 with a nucleolar pattern, whereas anti-Sjögren's syndrome-A/B, anti-DNA, anti-Jo-1, anti-U1-ribonucleoprotein, anti-topoisomerase I, anti-Sm, and anti-aminoacyl transfer RNA synthetase antibodies were all negative. Using an enzyme-linked immunosorbent assay that we had developed, serum anti-Mi-2, melanoma differentiation-associated gene 5, transcription intermediary factor-1γ, nuclear matrix protein 2, and small ubiquitin-like modifier activating enzyme-1 antibodies were found to be absent,5 while serum anti-PM/Scl100 (5.6 units) and PM-Scl75 (> 625 units) were present. A skin biopsy obtained from the nucha showed hyperkeratosis, epidermal atrophy, liquefaction degeneration, dermal edema and a perivascular lymphocytic infiltrate in the superficial dermis. Direct immunofluorescence was faintly positive for C3 and immunoglobulin M (IgM) along the dermoepidermal junction, but negative for IgG, IgA and C1q. We therefore made a diagnosis of DM. Chest computed tomography revealed ground glass opacities and reticular shadows at the base of the lower and middle lung fields bilaterally (Fig. 1). No abnormalities were detected in a screen for internal malignancy. We therefore made a diagnosis of DM with interstitial lung disease associated with anti-PM/Scl antibodies. Oral prednisolone 60 mg/day (1 mg/kg/day) and tacrolimus at 4 mg/day were administered with gradual improvement of his skin symptoms, muscle weakness, and interstitial lung disease, followed by tapering of the prednisolone dose. It is unclear whether anti-PM/Scl antibodies are present in Japanese patients with systemic autoimmune diseases because the enzyme-linked immunosorbent assay kit for anti-PM/Scl antibodies is not available in Japan. Only a small number of studies has examined the presence of anti-PM/Scl antibodies thus far. In one study of 52 Japanese patients with PM/DM, 113 with SSc and 54 with overlap syndrome, anti-PM/Scl antibodies were not detected.6 Furthermore, no anti-PM/Scl antibody-positive patients were found among 588 Japanese patients with SSc.7 Muro et al.1 screened the presence of anti-PM/Scl antibodies in 600 Japanese patients with various systemic autoimmune diseases. In total, 4/16 (25%) undifferentiated connective tissue disease patients, 3/126 (2.4%) DM patients, 1/223 (0.4%) SSc patients, and 1/88 (1.1%) Sjögren's syndrome patients were positive for anti-PM/Scl antibodies, while anti-PM/Scl antibodies were not found in patients with systemic lupus erythematosus (0/123), overlap syndrome (0/17), or PM (0/7). Thus, anti-PM/Scl antibodies were detected in patients with undifferentiated connective tissue disease, DM, SSc and Sjögren's syndrome, although the frequencies of anti-PM/Scl antibodies seem to be lower than those in European and North American patients. An association of anti-PM/Scl antibodies with human leukocyte antigen (HLA)-DRB1*0301 has been suggested,8 which is rare in Japanese patients, with a prevalence of 0.14%.1 Therefore, the HLA haplotype may affect the ethnic difference in the frequency of anti-PM/Scl antibodies. Thus far, only four cases of anti-PM/Scl antibody-positive DM affecting Japanese patients (three previously reported cases1 and the present case) have been reported (Table 1). All of the patients were male, over 50 years old. Myositis was observed in three cases (75%) and interstitial lung disease was found in all cases. Furthermore, two of these cases had malignancies (50%), whereas arthralgia was observed only in our case (25%). Regarding cutaneous manifestations, Gottron's lesions were observed in all cases and mechanic's hands were found in three cases (75%). Interestingly, all cases had hyperkeratotic symptoms of the soles, which resolved after treatment. By contrast, only 2/20 (10%) European patients with anti-PM/Scl antibody-positive PM/DM exhibited mechanic's hands.9 Hyperkeratotic lesions of the soles have not been shown in European and North American patients. Therefore, middle-age to elderly-onset disease, male preponderance, interstitial lung disease, myositis, Gottron's lesions, mechanic's hands and hyperkeratotic lesions of the soles may be distinctive features in Japanese or Asian patients with anti-PM/Scl antibody-positive DM. Furthermore, the screening for malignancies will be required because only 3/20 (15%) European patients with anti-PM/Scl antibody-positive PM/DM had malignancy.9 Accumulation of additional cases is required to clarify the clinical manifestations of DM associated with anti-PM/Scl antibodies in Asian countries, including Japan. Moreover, further studies are necessary to evaluate the significance of anti-PM/Scl antibodies in DM in each ethnic group, because investigation into various clinical manifestations in anti-PM/Scl antibody-positive patients who only have DM has not been performed. The authors declare no conflicts of interest.