Capillaroscopic analysis of the microvascular status in mixed versus undifferentiated connective tissue disease.

Abstract

Raynaud phenomenon (RP), typically, precede the clinical onset of systemic manifestations in several connective tissue diseases (CTDs). These autoimmune disorders usually share a microvascular damage whose alterations can be detected by nailfold videocapillaroscopy (NVC). The aim of the study was to compare the NVC microvascular status in Mixed Connective Tissue Disease (MCTD) versus the Undifferentiated Connective Tissue Disease (UCTD), and to search correlations between NVC findings and specific autoantibodies in UCTD patients. Clinical data and NCV patterns were retrospectively obtained from the files of 46 MCTD patients, 47 stable UCTD patients and 51 individuals with primary RP (PRP) as controls collected in a central database (VideoCap®, DS Medica, Milan, Italy). ANA and ENA Abs were tested respectively by indirect immunofluorescence and enzyme-linked immunosorbent assay. "Scleroderma-like" (SSc-like) NVC pattern was significantly more frequent in MCTD than in UCTD patients (48% vs 11%, p<0.001). Giant capillaries, abnormal shapes (i.e. neoangiogenesis) and lower capillary density were predominantly detected among MCTD versus UCTD patients (48% vs 11%, 49% vs 13%, 52% vs 9%, respectively, p<0.001). The absolute number of capillaries was significantly lower in MCTD versus UCTD patients (mean 7±1.7 SD vs mean 9.2±1.3 SD, respectively, p<0.001). Fully normal NVC pattern and non-specific NVC alterations were respectively observed in 6% and 46% of MCTD and in 6% and 83% of UCTD. Moreover, PRP patients showed normal NVC pattern and non-specific capillary abnormalities in 23% and in 77%, respectively. No statistically significant correlations were observed between NVC patterns and ANA patterns/specific ENA-Abs among the UCTD patients. The significant presence of the SSc-like NVC pattern and reduced number of capillaries seem the most typical NVC findings in MCTD in comparison to UCTD patients, suggesting a reflection of more complex and severe disease in MCTD ones.