POS0862 NAILFOLD CAPILLAROSCOPY IN UNDIFFERENTIATED AND MIXED CONNECTIVE TISSUE DISEASES

Background: Microvascular damage is a frequent feature in connective tissue diseases (CTDs) and can be easily detected trough nailfold videocapillaroscopy (NVC) (1,2). Mixed and Undifferentiated connective tissue diseases (MCTD and UCTD) do not show a specific and unique NVC pattern (3). However, a variety of microvascular abnormalities can occur in these two CTDs, both non-specific or specific for the scleroderma like-pattern (3-5). Objectives: To retrospectively assess and compare nailfold microangiopathy observed by NVC in MCTD and stable UCTD versus primary Raynaud’s phenomenon (PRP) (6). In addition, the aim was to correlate NVC findings with serum levels of autoantibodies (Abs) against extractable nuclear antigen (ENA) detected in UCTD. Methods: Files of fourty-six MCTD patients (Kasukawa’s criteria) (mean age 42.8±16 SD years), fourty-seven UCTD patients (mean age 47.7±16.1 SD years), fifty-one PRP (mean age 45.9±17.3 SD years) were retrospectively evaluated in the study. Among UCTD and MCTD patients 95% of both showed Raynaud’s phenomenon. Main NVC parameters (i.e. dilated capillaries, giant capillaries, microhemorrhages, abnormal shapes and number of capillaries) and related semiquantitative scale (score 0–3 for every parameter), were analyzed and compared between the two distinct CTD groups and PRP. Furthermore, ENA Abs (in particular, Ro/SSA, La/SSB, Scl70 and Jo1) were evaluated. The CTD patients were receiving different immunosuppressive treatments. Statistical analysis was performed by non-parametric tests. Results: Among UCTD group, 36% of patients showed a normal NVC pattern, 53% had non-specific NVC abnormalities and 11% had a scleroderma like-pattern. The latter was significantly more frequent in MCTD than in UCTD (p Conclusion: NVC features in UCTD patients seem very close to the pattern observed in PRP (mostly non-specific capillary abnormalities), conversely in MCTD the scleroderma-like pattern was found significantly prevalent together with a significant capillary number reduction. The transition from the scleroderma-like to the scleroderma pattern (mean systemic sclerosis) is matter of actual investigation. References: [1]Cutolo M. et al. Best Pract Res Clin Rheumatol 2008; 22:1093-108. [2]Sulli A, Ann Rheum Dis. 2008;67:885-7. [3]Smith V. et al. Autoimmunity Reviews 2020; 19:102458. [4]De Holanda Mafaldo DA, et al. Lupus. 2007; 16:254–8. [5]Smith V, et al. Ann Rheum Dis 2010; 69: 1092-96. [6]Antunes M, et al. RMD Open. 2019, 26;4. Disclosure of Interests: None declared