Background/Purpose:

Anti-aminoacyl-tRNA synthetase antibodies (anti-ARS antibodies) are related to Idiopathic Inflammatory Myopathy (IIM) and Anti-Synthetase Syndrome (ASS). While anti-TIF1-γ antibody and anti-NXP-2 antibody are highly related to malignancy, anti-Jo-1 antibody is reported as protective factor against complicating malignancy. We recently experienced a case of anti-PL-7 antibody positive clinically amyopathic dermatomyositis (CADM) with rapidly progressive interstitial lung disease (RP-ILD) and colon cancer (stage Ⅲa). Regarding clinically difficult situation of this case with severe ILD activity and massive tumor indication for surgery, we thought it is important to clarify the risk factors and incidence of malignancy in myositis patients with anti-ARS antibodies.

Methods:

Anti-ARS antibodies were detected by EUROLINE Myositis Profile 3. IIM diagnosis was made by the 2017 EULAR/ACR classification criteria and ‘probable’ cases meeting Bohan And Peter classification were included in this study between 2009 and 2018. Clinical features, laboratory and instrumental data were reviewed in this single center retrospective study. Cancer associated myositis(CAM) was defined by incidence of malignancy within 3 years from the diagnosis of IIM.

Results:

We identified 38 patients positive for Anti-ARS antibodies (Anti-Jo-1 13 cases, Anti-PL-7 12 cases, Anti-PL-12 5 cases, Anti-EJ 8 cases, Anti-OJ 0 case). Malignancies were complicated in 6/38 patients (15.8%, Anti-Jo-1 1/13 case, Anti-PL-7 5/12 cases), while patients negative for anti-ARS antibodies showed lower incidence (8/83 patients, 12.0%). All 6 patients with malignancy complicated with ILD and 3/6 patients (50%) developed RP-ILD. Prevalence of malignancy in Anti-PL-7 antibody positive patients was significantly high compared to other myositis associated antibodies. We then analyzed clinical features, laboratory data of Anti-PL-7 antibody positive patients with or without malignancy. No significant differences in clinical characteristics were seen but interestingly all 3 CADM patients complicated with malignancy.
We identified 429 cases of anti-ARS antibody positive IIM and ASS in the literature. Incidence of malignancy in anti-ARS antibody positive patients was reported around 6% up to 16% and controversial. No patients positive for Anti-PL-7 antibody complicated with malignancy. Anti-Jo-1 antibody showed the highest incidence of malignancy contrary to the previous reports.

Conclusion:

We should pay attention to malignancy screening in anti-ARS antibody positive patients same as other IIMs. Since all CADM patients positive for anti-PL-7 antibody complicated with malignancy, we may need to be cautious of malignancy in anti-PL-7 antibody positive CADM patients. Regarding the high frequency and severity of ILD in anti-ARS antibody positive patients even with malignancy, early detection and intervention of malignancy may lead to beneficial prognosis. 

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-malignancy-in-myositis-patients-with-anti-aminoacyl-trna-synthetase-antibodies-a-single-center-retrospective-study-and-literature-review/