Androgenetic alopecia
Androgenetic alopecia is characterized by predominance of trichoscopic abnormalities in the frontal area compared to the occipital area [1]. The progressive miniaturization of hair follicles is observed in trichoscopy as hair shaft thickness heterogenity (more than 20% of observed hair shafts are thinner that terminal hair shafts [3] and increased proportion of thin and vellus hairs (higher than 10%). Moreover, there is a tendency to observe follicular units with one or two hairs instead of predominance of follicular units with three or more hairs. [1] Other trichoscopic features are: presence of variable number of yellow dots and perifollicular discoloration (hyperpigmentation, peripilar sign) [1]
Diagnostic trichoscopic criteria for female androgenetic alopecia [1]:
Major criteria
More than four yellow dots in four images at a 70-fold magnification in the frontal area
Lower average hair thickness in the frontal area in comparison with the occiput (calculated from not less than 50 hairs from each area)
More the 10% of thin hairs (below 0.03 mm) in the frontal area
Minor criteria
Ratio of single-hair unit percentage, frontal area to occiput >2:1
Ratio of number of vellus hairs, frontal area to occiput >1.5:1
Ratio of hair follicles with perifollicular discoloration, frontal area to occiput >3:1
Fulfillment of two major criteria or one major and two minor criteria is required to diagnose female androgenetic alopecia.
- Rakowska, A., et al., Dermoscopy in female androgenic alopecia: method standardization and diagnostic criteria. Int J Trichology, 2009. 1(2): p. 123-30.
- Deloche, C., et al., Histological features of peripilar signs associated with androgenetic alopecia. Arch Dermatol Res, 2004. 295(10): p. 422-8.
- Blume-Peytavi, U., et al., S1 guideline for diagnostic evaluation in androgenetic alopecia in men, women and adolescents. Br J Dermatol, 2011. 164(1): p. 5-15.
- Rudnicka, L., et al., Trichoscopy update 2011. J Dermatol Case Rep, 2011. 5(4): p. 82-8.
- Waskiel, A., et al., Trichoscopy of alopecia areata: An update. J Dermatol, 2018.
