Supplementary Material for: The 100 Most Cited Publications in Lichen Planopilaris: A Bibliometric Analysis

Introduction: Lichen planopilaris (LPP) is a rare scarring alopecia with poorly understood etiology, leading to challenges in both diagnosis and management. With an increasing number of studies focused on its clinical presentation, histopathology, and trichoscopic features, a comprehensive bibliometric analysis of high-impact LPP research is necessary to assess current trends and identify gaps in the literature. Methods: To analyze trends in LPP research using the top 100 most-cited articles from Web of Science. Results: The average number of citations per article was 80.4 (range: 37-289), with publication dates ranging from 1990-2021. The most cited article was Kossard’s "Progressive Frontal Scarring Alopecia in Postmenopausal Women" with 289 citations. The United States (n=47) had the most publications, followed by England (n=18) and Spain (n=14). Most articles were LOE 3 (n=34) focusing on the "Clinical and Histopathological Presentation" (n=33). Key reported trichoscopic features included perifollicular erythema, perifollicular scaling, and loss of follicular ostia. Conclusion: This bibliometric analysis highlights foundational LPP studies, emphasizing key trichoscopic features while revealing gaps in high-level evidence. It underscores the need for more rigorous research and expanded geographic diversity to enhance diagnostic markers, refine trichoscopic criteria, and improve therapeutic approaches.