Skin Fibrosis Analysis by Raman Spectroscopy in Systemic Sclerosis

Systemic sclerosis (SSc) is a rare connective tissue disease characterized by a high clinical heterogeneity with unpredictable evolution that could engage functional and life-threatening prognosis. Most of patients develop skin fibrosis gradually spreading. Two clinical distinct forms are described according to the extension of skin fibrosis: limited (lSSc) and diffuse (dSSc) SSc. It is now admitted that a spreading of skin fibrosis is associated with poor prognosis. This disease can be complicated by pulmonary arterial hypertension (PAH), interstitial lung disease (ILD) and scleroderma renal crisis (SRC) representing the main causes of death in SSc. Usually, PAH is associated with lSSc, and ILD and SRC are associated with dSSc. Prognosis is also different regarding skin phenotype with a higher mortality rate in dSSc. An easy score, called modified Rodnan skin score, is commonly used in clinical practice to evaluate the spreading and severity of skin fibrosis, but this score is hardly reproducible. Ultrasound can be used to measure skin thickness and is more reproducible than the Rodnan skin score. Nevertheless, non-invasive analysis of fibrosis composition in different areas is not possible with these two technics. Thus, in this study we will investigate Raman spectroscopy, a non-invasive technic based on the interaction of a low-intensity laser with matter.