Dermoscopic Features of Morphea and Extragenital Lichen Sclerosus in Chinese Patients
Morphea and extragenital lichen sclerosus (ELS) are chronic inflammatory dermatoses that often present with similar clinical features, making their differentiation challenging, especially in early or atypical cases. Morphea is characterized by the development of erythematous patches, central hypopigmented sclerosis, and atrophic plaques, while ELS manifests as blue-whitish papules that coalesce into shiny, sclerotic, scar-like plaques. The clinical overlap between these conditions often necessitates biopsy for definitive diagnosis. However, dermoscopy, a non-invasive imaging technique, has emerged as a valuable tool in assisting the diagnosis of both neoplastic and non-neoplastic dermatoses. While previous studies have explored the dermoscopic features of morphea and ELS in Caucasian populations, this study aims to analyze and compare these features in Chinese patients.
This prospective study was conducted at the Department of Dermatology, Peking Union Medical College Hospital, Beijing, China, from January 2018 to August 2019. The study was approved by the hospital’s Ethics Committee, and all participants provided written informed consent. Patients with histopathologically confirmed morphea or ELS were included, while those who had received topical or systemic treatment within one month prior to consultation were excluded. All patients underwent physical examination, dermoscopic evaluation, and skin biopsy simultaneously.
Dermoscopic images were captured using a digital dermoscopy system (MoleMax HD, Digital Image Systems, Vienna, Austria) in polarized mode. Multiple images were taken to capture different parts of each lesion. Two separate dermoscopic analyses were performed: one per-image (each photograph as a unit for analysis) and one per-patient (each patient as a unit for analysis). These analyses were conducted independently by two experienced dermatologists blinded to the histopathologic results. This dual approach was adopted because inflammatory dermatoses often exhibit varying dermoscopic features across different lesions and even within different parts of the same lesion. Combining these analyses allowed for a more comprehensive understanding of the dermoscopic features and their incidences.
Dermoscopic variables were selected based on previous literature and preliminary observations. Statistical analysis was performed using SPSS 25.0, with Pearson Chi-squared tests, corrections, or Fisher exact tests used depending on the conditions. A P value of less than 0.05 was considered statistically significant.
The study analyzed 131 dermoscopic images from 25 patients with morphea (7 men and 18 women; mean age: 30.4 years) and 54 dermoscopic images from 11 patients with ELS (1 man and 10 women; mean age: 37.0 years). The results revealed distinct dermoscopic features for each condition.
In morphea, the most common dermoscopic features included white clouds, red structureless areas, linear curved vessels, and pigment networks. White clouds, previously described as “fibrotic beams,” were a hallmark of morphea and correlated with increased and thickened collagen bundles in the reticular dermis. These features were absent in ELS cases. In contrast, ELS was characterized by white structureless areas, follicular plugs, scales, purple dots, shiny white streaks, peppering, and rainbow patterns. White structureless areas, due to diffuse and dense superficial dermal collagen homogenization, were specific to ELS.
The differences in sclerotic features between the two conditions were statistically significant. White clouds were exclusive to morphea (P < 0.001), while white structureless areas were only observed in ELS (P < 0.001). Shiny white streaks, although present in both conditions, were more common in ELS (P < 0.001). These findings align with previous studies, highlighting the utility of these features in differentiating the two dermatoses.
Other notable differences included the presence of scales, rainbow patterns, follicular plugs, and purple dots, which were more frequently observed in ELS (P = 0.005, P = 0.005, P < 0.001, and P = 0.002, respectively). The prominence of purple dots in ELS may be attributed to more severe itching, leading to increased scratching and bleeding. Inflammatory features, such as red structureless areas and various vascular structures, were prevalent in both conditions. However, linear curved vessels showed a statistically significant difference (P < 0.001), with a higher frequency in ELS (81.5%) compared to morphea (48.1%). This difference may be explained by the fact that most included patients were in the inflammatory phase of their disease.
Pigmentary structures also provided differentiating clues. Pigmentation along skin grooves and perifollicular pigmentation were described for the first time in both conditions. Peppering and pigmentation along skin grooves were more common in ELS, with statistically significant differences (P < 0.001 and P = 0.036, respectively) in the per-image analysis.
In conclusion, this study demonstrated that dermoscopic features of morphea and ELS in Chinese patients are largely consistent with findings in Caucasian populations, albeit with some variations in frequency and distribution. The distinct dermoscopic features identified in this study, such as white clouds in morphea and white structureless areas in ELS, can aid in the clinical differentiation of these conditions. However, further research with larger sample sizes is needed to explore the influence of factors such as age, sex, anatomical sites, and disease phases on dermoscopic features. This study underscores the value of dermoscopy as a non-invasive diagnostic tool in dermatology, particularly in distinguishing between clinically similar conditions like morphea and ELS.
doi.org/10.1097/CM9.0000000000000977
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