Background Among patients, who meet the classification criteria for systemic sclerosis (SSc), there are the patients without specific SSc anti-nuclear antibodies and who are positive for antibodies to ribonucleoprotein (RNP). The clinical significance of the RNP antibodies in SSc is not clear.

Objectives To investigate clinical and laboratory characteristics of SSc patients positive for antibodies to RNP.

Methods The study included 52 patients (49 women and 3 men, mean age 44.2±15 years, median disease duration from the beginning of Raynaud's phenomenon 11.2±7years) who met the classification criteria of SSc (ACR/EULAR 2013) and have high level (>200 U/ml) of antibodies to RNP-70 (determined by ELISA, range 0–25 U/ml). Clinical, laboratory, and immunologic data were collected on all patients.

Results All the patients met the criteria for classification of SSc ACR/EULAR 2013 (table 1). Other prevalent clinical manifestations were gastroesophageal reflux in 63, 5% of patients, joints involvement in 58%, myositis in 30, 7%, serositis in 27.5% (including 23% of pericarditis). All patients were positive for antinuclear factor (Hep-2) and in some cases RF, anti-SS-A, anti-SS-B, anti-Sm and anti-dsDNA antibodies were identified. The increased levels of CRP and/or ESR were found in 56% of cases. Among the SSc patients, there were 38 (73%) who satisfied for the classification criteria for mixed connective tissue disease (MCTD) proposed by Kasukawa et al. (1987).

Conclusions In the group under study the limited form of SSc dominated, with high frequency of the different manifestations of vasculopathy, esophagus, joint and muscle disorders symptoms. A subtype of RNP-positive SSc patients often met the criteria for MCTD. This fact makes it reasonable to discuss the possibility of overlap-syndrome between these two diseases.

Disclosure of Interest None declared