Limited cutaneous systemic sclerosis: the unfairly neglected subset

Abstract

Systemic sclerosis (SSc) is an autoimmune disease and a disabling condition that reduces life expectancy. Disease heterogeneity is a hallmark of SSc and classification has been hard to establish. Moreover, within the SSc spectrum, subsetting according to the extent of skin involvement has been universally accepted and is used both for research purposes but also for patient care. Therefore, limited cutaneous (lcSSc) and diffuse cutaneous (dcSSc), with different severity and survival, have been recognized for several years as distinct subsets. Any SSc research project using human material takes into account the cutaneous subsets but it is striking to see that the dcSSc subset has been the subject of the very large majority of the research projects so far. This editorial indicates the comparative epidemiology of the two cutaneous subsets and summarizes the main results coming from the recent registries about the respective outcomes of the patients. The data demonstrate the predominance of the lcSSc subset and challenge some ideas that could suggest that the lcSSc subset might be a benign condition. Some clues are also provided regarding the future possibility to enroll more patients having the lc subset in clinical trials and potential shared outcome measures.