Background: Currently, the assessment of dermal thickness in Systemic Sclerosis (SSc) is performed by palpation with the modified Rodnan Skin Score (mRSS).
Objective: To verify if high frequency ultrasound (US) may be a reliable and a reproducible method to measure digital dermal thickness.
Methods: In 70 SSc patients, skin thickness was evaluated with US by two observers in two different sites of the second digit of the dominant limb to determine the inter-observer variability. Patients and controls were examined twice by the first observer for intra-observer variability. Patients were divided into three subgroups according to the phase of the disease (oedematous, fibrotic and atrophic).
Results: At both examined areas, US showed a significant dermal thickening (p<0,001) in the whole group of SSc patients. A low intra- and inter-observer variability was found. A highly significant correlation between the global mRSS and the local dermal thickness at the two examined sites (p:0.032 and p:0.021) was detected. Skin thickness resulted significantly higher in the oedematous than in the fibrotic group (p<0.001) and significantly higher in the fibrotic and the oedematous group (p<0.001) than in the atrophic group (p<0.002).
Conclusions: US is a reliable and reproducible tool, able to detect digital dermal thickening in SSc.