Hematological malignancy associated with polymyositis and dermatomyositis

The aims of this present study were to: 1) assess the characteristics of hematological malignancies in polymyositis/polymyositis (PM/DM) patients; and 2) determine predictive variables of hematological malignancies in PM/DM patients. We retrospectively reviewed the medical records of 32 patients (14 PM, 18 DM) associated with hematological malignancies. In our 32 PM/DM patients, hematological malignancy was concurrently identified (18.8%) or occurred during the course of PM/DM (31.2%); although, PM/DM more often preceded hematological malignancy onset (50%). We observed that the types of hematological malignancies varied, consisting of: B-cell lymphoma (n=20), T-cell lymphoma (n=4), Hodgkin's disease (n=2), multiple myeloma (n=1), myelodysplastic syndrome without excess of blasts (n=3), hairy cell (n=1) and acute lymphocytic leukemia (n=1). In 21 patients of our 32 patients with PM/DM-associated hematological malignancy (65.6% of cases), PM/DM paralleled the course of hematological malignancy. Finally, we observed that patients with PM/DM-associated hematological malignancies had a poor prognosis, the survival status ranging from 96.9%, 78.1% and 51.4% at 1, 3 and 5years, respectively. Interestingly, we found that patients with hematological malignancies, compared with those without were older and more frequently had DM; on the other hand, these patients less commonly exhibited: joint involvement (p=0.017), interstitial lung disease (p=0.06) and anti-Jo1 antibody (p=0.001). Taken together, our study underscores that the association between PM/DM and hematological malignancy, especially lymphoma, should not be ignored. Our findings also suggest that antisynthetase syndrome may be a protective factor of hematological malignancy in PM/DM patients.