Dermoscopy in female androgenic alopecia: method standardization and diagnostic criteria

Abstract

Objective: Establishing the trichoscopy criteria of female androgenic alopecia (FAGA).

Design: Trichoscopy images were retrospectively evaluated.

Setting: Dermatologic hospital-based clinic and private practice offices.

Patients and methods: One hundred and thirty-one females (59 with androgenic alopecia, 33 with chronic telogen effluvium (CTE), 39 healthy controls). The diagnosis was based on clinical examination and confirmed by histopatology.

Main outcome measure: Trichoscopy results obtained in frontal, occipital and both temporal areas of the scalp under a 20-fold and 70-fold magnification, including average hair thickness, number of 'yellow dots' and vellus hairs, number of hairs in one pilosebaceous unit and percentage of follicular ostia with perifollicullar hyperpigmentation.

Results: Average hair thickness in frontal area versus occiput was, respectively, 0.061 ± 0.008 mm versus 0.058 ± 0.007 mm in healthy controls, 0.047 ± 0.007 mm versus 0.052 ± 0.008 mm in androgenic alopecia and 0.056 ± 0.007 mm versus 0.053 ± 0.009 mm in CTE. Mean percentage of thin hairs (< 0.03 mm) in androgenic alopecia was 20.9 ± 12% and was significantly higher than in healthy controls (6.15 ± 4.6%, P < 0.001) or in CTE (10.4 ± 3.9%, P < 0.001). The number of yellow dots, pilosebaceous units with only one hair and with perifollicular hyperpigmentation was significantly increased in androgenic alopecia. Classification and Regression Tree Analysis was performed to establish diagnostic criteria for FAGA.

Conclusion: FAGA may be differentiated from CTE based on trichoscopy criteria. Major criteria are ratio of (1) more than four yellow dots in four images (70-fold magnification) in the frontal area, (2) lower average hair thickness in the frontal area compared to the occiput and (3) more than 10% of thin hairs (below 0.03 mm) in the frontal area. Minor criteria encompass increased frontal to occipital ratio of (1) single-hair pilosebaceous units, (2) vellus hairs and (3) perifollicular discoloration. Fulfillment of two major criteria or one major and two minor criteria allows to diagnose FAGA based on trichoscopy with a 98% specificity.

Keywords: Alopecia; dermoscopy; hair; trichoscopy; videodermoscopy.

Figure 1

Mean hair diameter in frontal, occipital and left temporal areas of patients with female androgenic alopecia (FAGA), chronic telogen effluvium (CTE) and healthy controls. Asterix indicates the most important, statistically significant differences between them (P < 0.001)

Figure 2

Percentage of thin, medium-sized and thick hairs in frontal and occipital areas in healthy controls, patients with female androgenic alopecia (FAGA) and chronic telogen effluvium (CTE). Asterix marks statistically significant differences (P < 0.05)

Figure 3

Trichoscopy of frontal scalp area in androgenic alopecia (a and b) and chronic telogen effluvium (c and d). Images presented in 70-fold (a and c) and 20-fold magnification (b and d). Red arrows: Vellus hairs; green arrows: Short, new anagen hairs; red asterix: Yellow dots

Figure 4

Percentage distribution of pilosebaceous units with one, two and three hairs. In chronic telogen effluvium patients as well as in the healthy controls, the distribution was similar. Thus, only healthy control results and patients with androgenic alopecia are presented

Figure 5

Yellow dots in frontal, occipital and left temporal areas of all three groups of patients, presented as a number counted in four field of visions at 70-fold magnifications. Asterix marks statistically significant differences (P < 0.001)