Diagnostic Accuracy of Trichoscopy in Inflammatory Scalp Diseases: A Systematic Review

Background: The common inflammatory scalp diseases, such as psoriasis, seborrheic dermatitis, lichen planopilaris, discoid lupus erythematosus, contact dermatitis, or pemphigus may share similar clinical features. Objective: To identify and systematically review the available evidence on the accuracy of trichoscopy in inflammatory scalp disorders. Methods: A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 58 articles were included in the analysis. Results: The following trichoscopy features were found to show the highest specificity for the respective diseases: in psoriasis: diffuse scaling, simple and twisted red loops, red dots and globules, and glomerular vessels; in seborrheic dermatitis: atypical vessels, thin arborizing vessels, and structureless red areas; in discoid lupus erythematosus: follicular plugs and erythema encircling follicles; in lichen planopilaris: milky red areas or fibrotic patches; in contact dermatitis: twisted red loops; in pemphigus foliaceus: white polygonal structures and serpentine vessels; in pemphigus vulgaris: red dots with whitish halo and lace-like vessels; and in dermatomyositis: lake-like vascular structures. Limitations: Different nomenclature and variability in parameters, which were analyzed in different studies. Conclusion: This systemic analysis indicates that trichoscopy may be used with high accuracy in the differential diagnosis of inflammatory scalp diseases.