Background/Purpose .  The modified Rodnan’s skin score (mRSS) is the validated method to detect both severity and extension of skin involvement, and high frequency skin ultrasound (US) is a valid and reproducible technique to measure dermal thickness (DT) in patients with systemic sclerosis (SSc) (1-4). Skin involvement is critical for sub-classification of the disease into different subsets (5). The aim of the study was to detect by US possible subclinical skin involvement in limited cutaneous SSc (lcSSc) patients, in those skin areas apparently not affected on the basis of a normal mRSS.

Methods .  Fifty lcSSc patients (ACR 2013 or LeRoy 2001 criteria) (mean disease duration 5±5 years) and fifty age-matched healthy subjects were analysed during clinical follow-up and after informed consent. Both mRSS and US were used to evaluate DT in the usual seventeen areas of the skin (cheeks, fingers, dorsum of hands, forearms, arms, chest, abdomen, thighs, legs, feet) of SSc patients. US was also performed in the same seventeen skin areas of healthy subjects, looking for DT differences in comparison with lcSSc patients. Nailfold videocapillaroscopy (NVC) was performed in lcSSc patients to identify the proper pattern of microangiopathy (Early, Active or Late) and calculate the microangiopathy evolution score (MES) (6-7). 

Results . US detected significantly higher DT in lcSSc patients than in healthy subjects in all skin areas with exclusion of thighs (p<0.0001 for all). In particular, DT was significantly higher in lcSSc patients than in healthy subjects in four out of six skin areas where the mRSS was normal (=0) (arms, chest, and abdomen) in agreement with the diagnosis of lcSSc. At the level of the thighs DT was higher in lcSSc patients than in healthy subjects, but this was not statistical significant (p=0.16). As assessed by US, a positive correlation was found between DT and both progressive NVC patterns (p<0.001) and MES (p=0.0015).

Conclusion . This study strongly suggests that subclinical diffuse dermal involvement may be detectable by high frequency skin ultrasound already in lcSSc patients in almost 70% of skin areas where the mRSS was normal. This observation should be of relevance for future classification of SSc disease subsets, since patients with either lcSSc or diffuse cutaneous SSc often display similar organ/laboratory markers of involvement.

References.  1. Clements PJ, et al. Arthritis Rheum 2000;43:2445-54.  2. Moore TL, et al. Rheumatology 2003;42:1559-63.  3. Sulli A, et al. Ann Rheum Dis 2014;73:247-51.  4. Kaloudi O, et al.  Ann Rheum Dis 2010;69:1140-3.  5. LeRoy EC et al. J Rheumatol 2001;28:1573-6.  6. Cutolo M, et al. Nat Rev Rheumatol 2010;6:578-87.  7. Sulli A, et al. Ann Rheum Dis 2008; 67:885-7.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/high-frequency-skin-ultrasound-detects-subclinical-diffuse-dermal-involvement-in-patients-with-limited-cutaneous-systemic-sclerosis/