Correlations between blood perfusion and dermal thickness in different skin areas of systemic sclerosis patients.

OBJECTIVE: To identify possible correlations between skin blood perfusion (BP) and dermal thickness (DT) in different skin areas of systemic sclerosis (SSc) patients. METHODS: Sixty-two SSc patients, according to 2013 EULAR/ACR criteria, and 62 healthy subjects (CNT) were enrolled. Skin BP was analysed by laser speckle contrast analysis (LASCA) at the level of dorsum of the middle phalanx of the third fingers, dorsal aspect of the hands and zygoma. DT was assessed by both skin high frequency ultrasound (US) and modified Rodnan skin score (mRSS) in the same above reported areas. All patients were studied also by nailfold videocapillaroscopy (NVC) to assess the proper pattern of microvascular damage ("Early", "Active", or "Late"). RESULTS: At the level of finger dorsum a statistically significant negative correlation was observed in SSc patients between skin BP and both ultrasound-DT (p=0.0005 r=0.43) and mRSS (p=0.0007 r=0.42), but not at the level of hand dorsum and zygoma. No statistically significant correlation was present between skin BP and ultrasound-DT at any level in CNT. In detail, SSc patients, compared to CNT, showed a statistically significant lower BP only at level of fingers (median PU 72.6 vs 136.1 respectively, p<0.0001) and a statistically significant higher ultrasound-DT at the level of dorsum of 3th finger bilaterally (median mm 0.9 vs 0.7, p<0.0001), dorsum of hands (median mm 0.9 vs 0.7, p<0.0001) and zygoma (median mm 0.8 vs 0.7, p<0.0001). A significant positive correlation between ultrasound-DT and mRSS was observed in SSc patients at level of the three areas (dorsum of fingers p<0.0001 r=0.51; dorsum of hands p=0.03 r=0.27; zygoma p=0.0001 r=0.45). A progressive decrease of skin BP and increase of ultrasound-DT was found correlated with the progression of the severity of NVC patterns. CONCLUSIONS: This study demonstrates for the first time in SSc patients a significant inverse relationship between skin BP, measured by LASCA, and DT, evaluated by both US and mRSS, at the level of dorsum of the middle phalanx of the third fingers.