Nailfold videocapillaroscopy alterations in dermatomyositis, antisynthetase syndrome, overlap myositis, and immune-mediated necrotizing myopathy.

INTRODUCTION/OBJECTIVES: The aim of our study was to investigate possible differences in nailfold videocapillaroscopy (NVC) features between patients with dermatomyositis (DM), overlap myositis (OM), antisynthetase syndrome (ASS), and immune-mediated necrotizing myopathy (IMNM). METHODS: We performed a cross-sectional monocentric study. All patients with inflammatory myopathies (IMs) over a 6-month period were analyzed by NVC for giant and ramified capillaries, tortuosities, capillary density, disorganization, and scleroderma pattern. Clinical, biological, and pathological characteristics were retrospectively recorded. Patients were classified as having DM, OM, ASS, or IMNM for comparison. Patients were also compared with a group of patients with systemic sclerosis (SSc). RESULTS: NVC was analyzed in DM (n = 17), OM (n = 8), ASS (n = 12), and IMNM (n = 6). Vascular disorganization and avascular zones were observed only in DM (11.8%) and OM (62.5%). The percentage of patients with giant capillaries was higher in OM (n = 4/8) than in DM (n = 3/17) and absent in ASS and IMNM. Frequency of ramified capillaries, tortuosities, hemorrhages, or thrombosis was not different between subgroups. A scleroderma pattern was only observed in OM patients. CONCLUSION: In this limited series of patients, we observed that DM and OM NVC abnormalities are different from ASS and IMNM. We could not determine NVC specific patterns associated with myositis-specific antibody subtypes of DM because of the small number of patients.Key Points• Nailfold videocapillaroscopy abnormalities are different in subgroups of inflammatory myopathies.• Giant capillaries, disorganization, and major capillary loss are observed in overlap myositis and dermatomyositis but not in antisynthetase syndrome (ASS) or immune-mediated necrotizing myopathy.• Nailfold videocapillaroscopy abnormalities in overlap myositis (with the exclusion of ASS) are close to systemic sclerosis.