High-Frequency Ultrasonography in Cutaneous Lupus Erythematosus.

Introduction: Cutaneous lupus erythematosus (CLE) is a chronic inflammatory autoimmune disease with not fully understood pathogenic mechanisms. The lesions in CLE are mainly located on the facial skin, that is why searching for noninvasive methods to facilitate differential diagnosis is justified. High-frequency ultrasonography (HFUS) is a noninvasive diagnostic tool, enabling the assessment of all skin layers without leaving a scar, in contrast to skin biopsy, which is the gold diagnostic standard in this disease. The aim of this study was to assess the usefulness of HFUS in the diagnostic process of patients with CLE, taking into account individual types of the disease, its severity and activity.

Materials and methods: For the purpose of analyzing the HFUS results, the studied lupus erythematosus (LE) group was divided into three subgroups: acute cutaneous lupus erythematosus (ACLE), subcutaneous lupus erythematosus (SCLE), and chronic cutaneous lupus erythematosus (CCLE). Fifty-seven active lesions and nine inactive lesions were examined. The analysis was performed using a 20 MHz Dermascan C linear head (version 3) (Cortex Technology; Hadsund, Denmark). In the analysis of the HFUS image, skin thickness, echogenicity of the skin, and the presence and thickness of subepidermal low echogenic band (SLEB) were taken into consideration. The image was compared with the healthy skin of the contralateral area and, if this was not possible, with the skin in the area of the lesion.

Results: HFUS images of 17 patients with active CLE (29.8%) showed the presence of SLEB and a statistically significant relationship between SLEB thickness and disease activity expressed by Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI-A) (p = 0.022). The average skin thickness of active foci was significantly greater than the average thickness of healthy skin (p = 0.001). Additionally, in the group of patients with CCLE, 55.6% showed increased skin echogenicity, showing its statistically significant inverse correlation with CLASI-A (p = 0.004).

Conclusions: SLEB can be treated as an indicator of the activity of the disease process. HFUS allows the assessment of certain features of healthy and diseased skin without performing a biopsy, but it cannot replace histological examination in the case of CLE diagnosis.