Trichoscopy pattern in alopecia areata: A systematic review and meta-analysis.

BACKGROUND: The incidence of alopecia areata (AA) has increased over the last few decades. Trichoscopy is a noninvasive procedure performed in dermatology clinics and is a helpful tool in determining the correct diagnosis of hair loss presentations. OBJECTIVE: Through mapping the researches that have been done to represent the spectrum of trichoscopic findings in AA and to identify the most characteristic patterns. METHODS: Thirty-nine studies were eligible for the quantitative analysis. Meta-analysis and subgroup analysis were performed. RESULTS: Thirty-nine studies (29 cross-sectional, five retrospective, two descriptive, one case series, one observational, and one cohort) with a total of 3204 patients were included. About 66.7% of the studies were from Asia, 25.6% from Europe, and 7.7% from Africa. The most characteristic trichoscopic findings of AA were as follows; yellow dots, black dots, broken hairs, short vellus hairs, and tapering hairs. CONCLUSION: There is no single pathognomonic diagnostic trichoscopic finding in AA rather than a constellation of characteristic findings. The five most characteristic trichoscopic findings in AA are: yellow dots, black dots, broken hairs, short vellus hairs, and tapering hairs. Yellow dots and short vellus hairs considered the most sensitive clues for AA, while black dots and tapering hairs are the most specific ones. Furthermore, trichoscopy is a useful tool that allows monitoring of response during the treatment of AA. Treatment responded cases will show an increase in short vellus hairs, but loss of tapering hairs, broken hairs, and black dots, while yellow dots are the least responsive to the treatment.