Inflammatory myopathies associated with myelodysplastic syndromes: A French multicenter case control study and literature review.

Objective: Patients with inflammatory myopathies (IM) are known to have an increased risk of developing malignancies. Autoimmune and inflammatory diseases occur in up to 25% of patients with myelodysplastic syndrome (MDS). This study aimed to describe the rare association between IM and MDS.

Methods: We report here the main characteristics, treatment, and outcome of 21 patients (11 national cases and 10 additional cases from a literature review) with IM associated to MDS.

Results: Median age of patients at IM diagnosis was 66 years (range 26 - 78). Diagnosis of the two conditions were concomitant in most patients (n=14/21) whereas MDS diagnosis preceded IM diagnosis in 5 patients. Different types of IM were observed but dermatomyositis was the most frequent (59%). Compared to IM without MDS (IM/MDS), patients with MDS (IM/MDS) were older (median 66 vs 55, p=0.3), more frequently male (sex ratio M/F 1.125 vs 0.41, p=0.14) and positive for anti-TIF1γ (24% vs 4%, p=0.0039). Antisynthetase syndrome was never observed among IM/MDS patients (0% vs 28%, p=0.01). MDS WHO type was not univocal, but the prognostic score was of low risk in almost all cases. IM was usually steroid sensitive (82% of patients) but often steroid dependent (56% of patients). Overall survival of IM patients with MDS was worse compared to patients with IM without MDS (p=0.0002).

Conclusion: IM associated with MDS are mainly represented by dermatomyositis and/or anti-TIF1γ autoantibodies. Antisynthetase syndrome has not been described in association with MDS. Despite low-risk MDS, overall survival of IM patients with MDS is worse than IM patients without MDS.