Classification of systemic sclerosis in the Japanese population based on rapid progression of skin thickening

In general, patients with systemic sclerosis (SSc) have been classified in two clinical subsets (diffuse and limited) based on the extent of skin thickening, and the extent of skin fibrosis is closely related to the severity of organ involvement and mortality rates. In addition, there is a rapid progression of skin thickening in diffuse cutaneous SSc (dcSSc). In this study, we classified a novel subset of SSc based on the rate of skin thickening progression, and evaluated the relationship of the subset to disease severity and laboratory markers. Thirty-three patients with dcSSc were included in the study. Participants who had a modified Rodnan's total skin thickness score higher than 15 points within a year from the first symptoms were defined as having rapidly progressive SSc (RPSSc; group 1), while all the other dcSSc patients were defined as having non-RPSSc (group 2). The frequencies of interstitial lung disease and renal crisis were significantly higher in group 1 than in group 2. The frequencies of anti-topoisomerase I antibody (anti-topo I) and anti-SS-A antibody were significantly higher in group 1 than in group 2. Conversely, the frequency of anticentromere antibody was significantly higher in group 2 than in group 1. This study demonstrates the clinical significance of a new subset of SSc (defined as RPSSc), which is characterized by a markedly rapid progression of skin thickening. This new classification may be useful for predicting the prognosis of SSc at an early stage, so that patients who should receive aggressive therapy with immunosuppressants might be identified.