Background/Purpose:

Polymyositis (PM) and dermatomyositis (DM) are systemic connective tissue disorders, which are often associated with internal malignancy. Several studies have reported the association between autoantibodies (Abs) and clinical manifestations of the disease. In adult PM/DM, the association of malignancy with anti-p155/140 Ab is reported. However, background of association of malignancy in whole IIM patients is currently unclear. Here,we intended to analyze the clinical and serological associations of malignancy in adult IIM patients.

Methods:

Clinical data and serum samples were collected from 207 adult Japanese patients with PM/DM (119 with DM and 88 with PM). Myositis-specific Abs were screened using the RNA immunoprecipitation assay  (anti-ARS and anti-SRP) and immunoprecipitation with [³⁵S] methionine-labelled HeLa cells (anti-p155/140 and anti-CADM-140).

Results:

30 patients (14.5%,15 females and 15 males) had history of malignancies.20 patients (66.7%) were DM and 10 patients were PM (33.3%).No certain common cancer types were not recognized.In comparison with malignancy-negative patients,the average age at IIM onset was higher in malignancy-positive IIM patients (52.3 vs 59.6 years). Among malignancy-positive IIM patients,anti-p155/140 (N = 10,33.3%) and anti-ARS  (N = 13,43.3%) predominated.2 (6.7%) were anti-SRP positive,1 (3.3%) was anti-CADM140 positive,and other 3 (10%) patients were positive for unknown Ab that immunoprecipitated a 120kDa protein.Anti-p155/140 showed the strong association with the onset of myositis and malignancy.All anti-p155/140-positive patients were diagnosised progressive malignancies at the same time of DM onset, while the onset of myositis proceeded 6.1 years at average before malignancy in 9 (69%) anti-ARS-positive patients. In addition,all anti-p155/140-positive patients were DM,whereas 46.2% (N=6) of anti-ARS-positive patients were PM. Onset age of patients with anti-p155/140 Ab were higher than that of patients with other Abs (65.7 vs 56.6).

Conclusion:

Anti-p155/140 Ab and anti-ARS Abs were predominantly found among PM/DM patients associated with malignancy.Malignancies in PM/DM patients with anti-p155/140 were all diagnosed at the onset of DM,whereas the onset of malignancies in patients with anti-ARS did not coincide with myositis.These results suggest that different mechanisms maybe present in the association with malignancy and myositis between the two antoantibody-positive patient groups. Screening of autoantibodies and work up of malignancy are recommended in advanced age patients with a new diagnosis of DM.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-and-serological-associations-of-malignancy-in-adult-patients-with-polymyositis-and-dermatomyositis/