Trichoscopy: Essentials for the dermatologist

Table 4 Trichoscopic findings in common types of non cicatricial alopecia

AGA	AA	Telogen effluvium	Trichotillomania
Hair shaft thickness heterogeneity	Exclamation mark hairs	Empty follicles	Simultaneous, chaotic coexistence of multiple hair shaft abnormalities
Increased proportion of vellus hairs	Broken hairs	Increased proportion of single-hair follicular units	Hairs broken at different lengths
> 10% thin hairs in the frontal area	Clustered short vellus hairs	Short regrowing hairs	Short hairs with trichoptilosis (split ends)
Increased proportion of single-hair follicular units	Pigtail hairs	< 20% hair diameter diversity	Coiled hairs
Yellow dots	Black dots	Brown perifollicular discoloration	Exclamation mark hairs
Perifollicular discoloration (peripilar sign)	Numerous yellow dots	No significant difference between frontal and occipital areas	Black dots
All the trichoscopic features appear most prominently in the frontal scalp area compared to the occipital area			Others: flame hairs, V-sign, hook hairs, hair powder and tulip hairs

AGA: Androgenetic alopecia; AA: Alopecia areata.