Linear alopecia in pediatrics: RCM and dermoscopy reveal diagnostic cues

BACKGROUND: Alopecia areata (AA), trichotillomania (TM), nevus sebaceous (NS), and linear scleroderma en coup de sabre (LSCS) can all present with a patch of linear alopecia, making diagnosis challenging. The purpose of this study was to combine reflectance confocal microscopy (RCM) and dermoscopy in the diagnosis of these lesions in children. METHODS: A total of 36 patients with linear alopecia were enrolled, of whom 14 had AA, seven had TM, nine had NS, and six had LSCS. We evaluated the characteristics and distinguishing features of the four conditions using RCM and dermoscopy. RESULTS: The key to differential diagnosis was the dermal Hair follicle density in the dermis was decreased in AA, and the size and density of the follicular openings were normal in TM. In NS, the major features were petal‐like and frogspawn‐like structures. In LSCS, dermal papillary rings, sebaceous glands, and follicles were partially or completely missing, and abundant fibrous material was distributed in the dermis. Dermoscopy revealed alopecia, and all four conditions resulted in decreased hair density. AA patients exhibited yellow dots, black dots, and exclamation mark hairs. TM patients presented with irregularly broken hairs and blood spots. Both NS and LSCS patients exhibited an absence of follicular openings; NS patients demonstrated whitish and yellowish round structures, while an atrophic area with white patches, linear vessels, and no yellow or black dots was observed in LSCS patients CONCLUSION: RCM combined with dermoscopy can provide additional information on disease states and differentiate between AA, TM, NS, and LSCS.