Skin sclerosis is only of limited value to identify SSc patients with severe manifestations - An analysis of a distinct patient subgroup of the German Systemic Sclerosis Network (DNSS) Register

Objectives. In SSc, diagnosis and classification is based mainly on skin sclerosis. Herein, we investigated in a large multicentre cohort, to what extent skin sclerosis reflects organ involvement and additional clinical symptoms. Methods. A total of 1200 SSc patients from the register of the German Systemic Sclerosis Network (DNSS), classified as either lcSSc or dcSSc, were analysed for their serological characteristics, clinical symptoms and organ manifestations in relation to skin involvement measured by the modified Rodnan skin score (mRSS). Results. SSc patients with different mRSS did not differ significantly in their disease duration and in most of the clinical symptoms. They showed a similar distribution of most organ manifestations such as pulmonary arterial hypertension as well as cardiac, renal and nervous system involvement. More severe skin thickening was found to be associated with pulmonary fibrosis and gastrointestinal symptoms, as well as with digital ulcers and musculoskeletal involvement. Conclusions. In patients with SSc, potentially life-threatening complications and clinical symptoms with high impact on the quality of life occur independently from the extent of skin sclerosis. The diagnosis in SSc patients with a low mRSS could be missed or they could be insufficiently treated.