Background New ultrasound techniques (high frequency ultrasound, elastography) have been put in the clinical practice in recent years for the detection of skin involvement in Systemic Sclerosis (SSc). The modified Rodnan skin score (mRSS) is a standard measure used to evaluate severity and extent of skin involvement. The limitations of mRSS include the intraobserver and interobserver variability as well as the necessity of standardization.

The pulmonary involvement is very common feature in patient with SSc and the gold standard of its detection was high resolution CT (HRCT). There exist a few studies in the past several years indicating that the Lung ultrasound (LUS) could substitute HRCT in screening of pulmonary interstitial complications.

Objectives To determine the correlation between the dermal thickness revealed by high frequency ultrasound and the presence of B-lines at LUS examination in early diffuse SSc.

Methods 42 patients with diffuse SSc have been identified in the present stusy by the extent of skin involvement. All subjects have met the ACR diagnostic criteria for SSc. The disease duration have been ≤3 years.

The dermal thickness have been measured by means of an 18MHz probe at five different anatomical sites: phalanx, hand, forearm, leg, chest. The obtained values for all sites have resulted in an average skin thickness.

LUS have been performed with 2.5-3.5 MHz transducer for anterior, posterior and lateral chest consecutively in determinated areas. LUS examination have been aimed at searching for B-lines, the sonographic marker of interstitial lung disease.

Results Patients with diffuse SSc have revealed high dermal thickness during the early edematous phase. This finding correlates with the increased number of B-lines, detected at the LUS examinations.

The results of the examinations have been characterized by the following statistical quantities: (i) mean value of dermal thickness x=1.77±0.21, (ii) 73.8±2.4% from the group of patients shows values of B-lines, which are greater than 6, (iv) the correlation is significant at P=0.01 for both methods applied: direct and significant relationship at the following correlation coefficients: Kendal 0.82, Spearman's rxy =0.93, Pearson 0.924.

Conclusions A strong correlation has been found in this study between the dermal thickness examined at five anatomical sites and the total amount of B-lines at LUS examination of patients with diffuse SSc. Our opinion is that these new tools could support the diagnostic accuracy in patients with early SSc

References

1. Olga Kaloudi, Francesca Bandinelli, Emilio Filippucci, et al. High frequency ultrasound measurement of digital dermal thickness in systemic sclerosis. Ann Rheum Dis 2010 69: 1140-1143.

2. Manal Mohamed Sedky, Samar Mohamed Fawzy, Noha Abd El Baki, et al. Systemic sclerosis: an ultrasonographic study of skin and subcutaneous tissue in relation to clinical findings. Skin Res Technol 2013; 19: e78-e84.

3. R. Hesselstrand, A. Scheja, M.Wildt and A. Akesson. High frequency ultrasound of skin involvement in systemic sclerosis reflects oedema, extension and severity in early disease. Rheumatology 2008;47:84-87.

Disclosure of Interest None declared