Overlap syndromes in systemic sclerosis

Introduction
It is known, that course of the disease differs between overlap syndromes (OS) and systemic sclerosis (SSc) group.

Aim
To compare the prevalence of OS in limited cutaneous systemic sclerosis (lcSSc) and diffuse cutaneous SSc (dcSSc) and to analyze the presence of different manifestations in the SSc and OS group.

Material and methods
The study included 126 European Caucasian SSc patients (99 females and 27 males) hospitalized consecutively in the Department of Rheumatology and Connective Tissue Diseases. Patients fulfilled the American College of Rheumatology (ACR) classification criteria of SSc (57 – dcSSc and 69 – lcSSc). The study groups were determined according to the subtype of SSc, coexistence of other connective tissue diseases (CTDs), and incidence of clinical and serological manifestations.

Results
In our SSc study group, 28/126 patients (22%) were affected by more than one CTD. The prevalence of OS was significantly higher in the lcSSc group – 33% (23/69) compared to the dcSSc group – 8% (5/57). We found that mortality and digital ulcers were significantly higher, whereas kidney involvement and arthritis were significantly lower in the SSc group compared to the OS group. The prevalence of anti-topoisomerase I (a-Scl-70) was significantly higher, and prevalence of anti-PM/Scl, anti-Ro-52 antibodies was significantly lower in the SSc group compared to the OS group.

Conclusions
Overlap syndromes were more common in lcSSc than in dcSSc. The course of the disorder and internal organ involvement were different in OS compared to SSc patients.