**Background:** Alopecia areata (AA) is a common cell-mediated autoimmune nonscarring hair loss disease with an estimated prevalence of 1 in 1000 people and a lifetime risk of 2% in the general population. Trichoscopy is a noninvasive method for examining the scalp and hair that can aid diagnosis and monitoring. This systematic review and meta-analysis aimed to map the spectrum of trichoscopic findings in AA and identify the most characteristic patterns.
**Methods:** The protocol was registered in PROSPERO (CRD42022326248) and adhered to PRISMA guidelines. An intensive literature search was conducted across Google Scholar, Scopus, EBSCO, and PubMed from 2004 to July 2022. Inclusion criteria were full-text English-language studies on trichoscopic findings in AA (cross-sectional, observational, descriptive, cohort, retrospective, comparative, and case series). Exclusion criteria included animal studies and studies lacking main epidemiologic data. Two independent reviewers screened titles/abstracts and extracted data. Quality assessment was performed using the modified Newcastle-Ottawa Scale (NOS). Meta-analysis was conducted using R 4.0.3 with the 'meta' package; random-effects models were used when heterogeneity was high (I² > 50%). Subgroup analyses and meta-regression were performed. Publication bias was assessed using funnel plots and Egger's test.
**Key Results:** Thirty-nine studies (29 cross-sectional, 5 retrospective, 2 descriptive, 1 case series, 1 observational, 1 cohort) with a total of 3204 patients were included. Continental distribution: 66.7% from Asia, 25.6% from Europe, 7.7% from Africa. The overall pooled prevalence of the five most characteristic trichoscopic findings were: yellow dots 61.0% (95% CI 52.0–70.0%; I²=92.0%), black dots 56.0% (95% CI 49.0–63.0%; I²=90.0%), broken hairs 40.0% (95% CI 32.0–49.0%; I²=92.0%), short vellus hairs 46.0% (95% CI 39.0–52.0%; I²=90.0%), and tapering hairs 35.0% (95% CI 29.0–41.0%; I²=91.0%). In subgroup analysis by continent, the highest prevalence of yellow dots was in African studies (72.0%; 95% CI 41.0–90.0%), black dots in African studies (63.0%; 95% CI 51.0–73.0%), broken hairs in Asian studies (41.0%; 95% CI 31.0–51.0%), short vellus hairs in African studies (74.0%; 95% CI 19.0–93.0%), and tapering hairs in African studies (47.0%; 95% CI 36.0–59.0%). Subgroup differences by continent were not significant for most findings. Yellow dots prevalence was higher in children-only studies (68%; 95% CI 45–84%) compared to adults-only studies. Meta-regression showed that study sample size (coefficient = −0.006; p = 0.021) and non-cross-sectional study design (coefficient = −0.809; p = 0.026) were significantly associated with black dots prevalence. Cross-sectional design significantly decreased short vellus hairs prevalence (coefficient = −0.961; p = 0.0019). Publication bias was detected for black dots (Egger test p = 0.015); after trim-and-fill correction, the adjusted prevalence was 47.4% (95% CI 39.7–55.1%). Yellow dots and short vellus hairs were identified as the most sensitive diagnostic clues, while black dots and tapering hairs were the most specific. Regarding treatment monitoring, responded cases show an increase in short vellus hairs and loss of tapering hairs, broken hairs, and black dots, while yellow dots are the least responsive to treatment.
**Clinical Implications:** Trichoscopy is a valuable noninvasive tool for diagnosing AA and monitoring treatment response. The constellation of yellow dots, black dots, broken hairs, short vellus hairs, and tapering hairs is characteristic of AA, with no single pathognomonic finding. Yellow dots and short vellus hairs provide the most sensitive clues, while black dots and tapering hairs offer the highest specificity. Trichoscopy can help differentiate AA from other hair loss conditions such as tinea capitis, trichotillomania, and androgenetic alopecia, potentially reducing the need for scalp biopsies. The ability to monitor treatment response through trichoscopic changes (increased short vellus hairs, decreased black dots, broken hairs, and tapering hairs) can guide clinical management and encourage patient adherence to therapy.