Trichoscopic characteristics as diagnostic indicators for grading of female pattern hair loss severity in skin of color: A multicentric retrospective study by the International Dermoscopy Society

Objectives: Female pattern hair loss (FPHL) is a common non-scarring alopecia characterized by progressive follicular miniaturization. The Sinclair scale is widely used for clinical grading but lacks objective quantification. Trichoscopy provides measurable parameters that may improve diagnostic precision. The objectives of the study are to evaluate trichoscopic parameters as indicators of Female pattern hair loss (FPHL) severity and to develop and validate a quantitative trichoscopic grading system in comparison with the Sinclair scale. Material and Methods: This retrospective multicentric study under the aegis of the International Dermoscopy Society included 279 treatment-naïve females (18–50 years) with FPHL. Trichoscopy was performed at standardized frontal scalp points using polarized dermoscopy. Parameters assessed included hair count, shaft diameter, single hair units, terminal-to-intermediate/vellus (T: I–V) ratio, and qualitative features (hair diameter diversity, yellow dots, and peripilar sign). Patients were graded using the Sinclair scale. A novel quantitative grading system (score range 4–20) based on four parameters was applied. Statistical analysis included analysis of variance (ANOVA), Pearson correlation, and Chi-square tests. Results: Most patients were Grade 3 (47%) and Grade 4 (36.6%). Significant progressive decline was observed in hair count (172 ± 10–92 ± 12 hairs/cm 2 ), shaft diameter (66 ± 5–33 ± 3 μm), and T: I–V ratio (3.4 ± 0.6–0.4 ± 0.3) with increasing severity, while single hair units increased (34 ± 5–63 ± 3%). Strong negative correlations were noted between grade and hair count (r = −0.60), diameter (r = −0.65), and T: I–V ratio (r = −0.67) ( p < 0.01). ANOVA showed significant differences across grades for all major quantitative parameters ( p < 0.001), except T: I–V ratio. Qualitative features lacked grading specificity. Conclusion: Trichoscopic quantitative parameters are reliable indicators of FPHL severity. The proposed grading system complements the Sinclair scale by providing an objective, reproducible tool for early diagnosis, severity assessment, and treatment monitoring.