Clinical Features and Prognosis of Double-Positive Anti-MDA5 and Anti-CCP Antibodies in Dermatomyositis: A Retrospective Study.

OBJECTIVE

To investigate the clinical features and prognosis of anti-melanoma differentiation-related gene 5 (MDA5) antibody and anti-cyclic citrullinated peptide (CCP) antibody double-positive dermatomyositis (DM) (MDA5+/CCP+ DM).

METHODS

A retrospective analysis of 264 consecutive cases of MDA5+ DM hospitalized from March 2018 to March 2022, and patients with anti-CCP antibodies were screened out. Patients from MDA5+/CCP- served as the control. Propensity score matching was used to compare the clinical features, as well as the treatment and survival outcomes between the two groups.

RESULTS

A total of 18 patients (6.8%) with MDA5+/CCP+ DM were identified. Gottron's sign in 17 cases (94.4%), Heliotrope rash in 14 cases (77.8%), and skin ulcer in 5 cases (27.8%). Arthritis occurred in 10 cases (55.6%) and presented as the initial symptom in 6 cases (33.3%). Only 8 (44.4%) of the patients met the criteria for rheumatoid arthritis (RA). Interstitial lung disease (ILD) was diagnosed in 17 cases (94.4%), with non-specific interstitial pneumonia (NSIP) and organizing pneumonia (OP) combined with NSIP being the most predominant, as they presented in 6 cases (33.3%) each. Two of the ILD cases (11.1%) developed into rapidly progressive ILD (RP-ILD). Arthritis (55.6% vs 15.3%, p = 0.001) and malignancy (22.2% vs 0%, p < 0.001) were significantly more common in the MDA5+/CCP+ group compared to the MDA5+/CCP- group. The clinical manifestations of MDA5+/CCP+ DM with or without anti-Ro-52 antibody were not significantly different from those of the ILD type. During the follow-up period, there was no significant difference in survival between the two groups.

CONCLUSION

More than half of the patients with MDA5+/CCP+ DM may present with arthritis as one of the initial symptoms. They may also have an increased risk of malignancy. For MDA5+ DM patients with positive anti-CCP antibodies, thorough screening for tumors is crucial to guide treatment and improve prognosis.