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Dermatomyositis (DM) is an idiopathic systemic inflammatory disease that is often accompanied by interstitial lung disease (ILD) or internal malignancy. New autoantibodies, anti-clinically amyopathic dermatomyositis 140 (anti-CADM-140) antibody (Ab) and anti-155/140 Ab, as well as anti-aminoacyl-tRNA synthetase (anti-ARS) Ab and anti-Mi-2 Ab, have been discovered and their utility indicated. However, the association between these autoantibodies and the clinical characteristics of DM is not fully understood, and it is unclear whether anti-155/140 Ab is "specific" to DM patients with internal malignancy. Therefore, we analyzed 55 DM patients and 18 non-DM patients with malignancy to evaluate the clinical characteristics, especially skin manifestations, in association with DM-specific autoantibodies detected by immunoprecipitation. Six patients (11%) had anti-CADM-140 Ab, nine (16%) had anti-155/140 Ab, eight (15%) had anti-ARS Ab and six (11%) had anti-Mi-2 Ab. The frequency of DM patients positive for any type of autoantibody was 53%. Among the 20 DM patients with ILD, three (15%) had both anti-CADM-140 Ab and rapidly progressive ILD, and required intensive therapy (P < 0.05). ILD found in anti-ARS Ab-positive patients did not progress rapidly. The prevalence of muscle involvement in patients with anti-CADM-140 Ab was 83%. Among the 18 DM patients with internal malignancy, four (22%) had anti-155/140 Ab, and internal malignancy was found in four cases (44%) of nine anti-155/140 Ab-positive patients. None of the non-DM patients with malignancy were positive for anti-155/140 Ab. In conclusion, the results of the present study indicate that anti-155/140 Ab is specific to DM patients with internal malignancy and that we may be able to predict prognosis of ILD and the presence of malignancy to some extent, suggesting that examination of autoantibodies in DM patients is clinically very useful. However, further investigation is needed because several findings differ from those of previous reports.

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Dermatomyositis (DM) is an autoimmune inflammatory disease characterized by skin eruptions and myositis. Anti-transcriptional intermediary factor 1-c antibody (anti-TIF1-c Ab) is one of the most frequently detected myositis-specific autoantibodies and adults positive for anti-TIF1-c have markedly higher rates of malignancy. Our aim was to determine the clinical associations of anti-TIF1-c levels in 31 Japanese adult DM patients positive for anti-TIF1-c. We determined associations between the anti-TIF1-c index and patient characteristics and disease severities. Sixteen patients with anti-TIF1-c Ab had concomitant malignancies. A mild positive correlation was found between the levels of serum creatine phosphokinase at the first visit and anti-TIF1-c levels. In contrast, there was no significant difference in the anti-TIF1-c Ab index between patients with and without malignancy. Dysphagia tended to be observed in patients with malignancy. On sequential analysis, anti-TIF1-c levels in patients without malignancy were lower or turned negative after treatment for DM. Ab titers tended to be sustained in patients with stage IV malignancies. Interestingly, a re-increase in the Ab titer was observed on recurrence of malignancy or increase in DM activity. Four patients were completely cured of their malignancies, and anti-TIF1-c levels in three patients turned negative with the loss of DM activity. These data suggest that higher anti-TIF1-c titers may not directly indicate the presence of malignancy. Nevertheless, longitudinal changes in the anti-TIF1-c index in individual patients may partially reflect activities of both DM and malignancy.

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