IS THERE A ROLE FOR ULTRA-HIGH FREQUENCY ULTRASOUND IN THE ASSESSMENT OF SKIN INVOLVEMENT IN SYSTEMIC LUPUS ERYTHEMATOSUS? PRELIMINARY INSIGHTS FROM A MONOCENTRIC COHORT

Background/Purpose The assessment of skin involvement in Systemic Lupus Erythematosus (SLE) can represent a challenge for clinicians, not only in the differential diagnosis with other dermatological conditions but also in discerning SLE cutaneous disease activity from damage. This results in a need to optimize the management of SLE patients with mucocutaneous involvement, as the development of skin damage may be early during disease course. Ultra-high frequency ultrasound (UHFUS), with submillimeter resolution, is a promising tool for evaluating superficial structures, finding increasing application in the field of dermatology in recent years. The aim of the study was to explore a possible role of UHFUS assessment in the evaluation of skin involvement in a monocentric cohort of SLE patients. Methods Consecutive adult SLE patients (2019 EULAR/ACR criteria) regularly followed at our Lupus Clinic were prospectively enrolled during a scheduled outpatient visit in presence of skin lesions. Demographical, clinical, serological and treatment data were collected at enrollment. Disease activity and organ damage were evaluated with the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and SLICC/ACR Damage Index (SDI), respectively. Clinical assessment of skin lesions was done by an experienced rheumatologist using the Cutaneous LE Disease Area and Severity Index (CLASI); at the same time, UHFUS evaluation of skin lesions was performed with a 70 MHz probe by an experienced dermatologist. The Skindex-16 questionnaire was used to assess the impact of skin involvement on patients’ quality of life. Results We included 94 assessments in 59 SLE patients with skin lesions. Cutaneous disease subtypes were distributed as follows: 18/59 acute (30.5%), 8/59 subacute (13.6%), 27/59 chronic (45.8%); a minority of patients had nonspecific skin lesions (10.2%). The characteristics of the cohort are detailed in Table 1. At the clinical evaluation, concomitant presence of active lesions and skin damage was observed in 52/94 cases (55.3%), presence of active skin lesions without damage in 40/94 cases (42.6%), while only skin damage in 2/94 cases (2.1%). The most frequent UHFUS alteration was the presence of power Doppler (68/94, 72.3%), followed by dermal edema (43/94, 45.7%), dermal inhomogeneity (41/94, 43.6%), follicular plugging (37/94, 39.4%), vascular ectasia (30/94, 31.9%), thinning (11/94, 11.7%) and thickening (9/94, 9.6%) of the epidermis. The CLASI activity score was significantly higher in cutaneous areas with power Doppler signal (p = 0.005). Dermal edema was also found to be associated with higher CLASI activity scores, considered both globally (p = 0.004) and at the level of the US-evaluated area (p < 0.001). Skindex-16 symptoms subscale scores were significantly higher in patients with UHFUS findings of power Doppler (p = 0.01) and thinning of the epidermis (p = 0.04). Moreover, we found a positive correlation between CLASI activity and the scores of all Skindex-16 subscales (Rho 0.324, p = 0.002 for symptoms; Rho 0.312, p = 0.003 for emotions; Rho 0.378, p < 0.001 for functioning), also present but weaker between CLASI-Damage and the symptoms (Rho 0.228, p = 0.032) and functioning (Rho 0.275, p = 0.009) domains. Conclusions Our preliminary data demonstrate that UHFUS presence of power Doppler and dermal edema is associated with skin activity clinically assessed by CLASI. These findings suggest that UHFUS may play a role in supporting the clinician in the differential diagnosis between active skin lesions and damage, to optimize the management of skin involvement in SLE.