Hair follicle opening
"Dots" correspond to hair follicle openings observed in trichoscopic examination [1].
Black dots
Black dots, also known as “cadaverized hairs”, represent pigmented hairs broken or destroyed at scalp level [1]. They are commonly observed in alopecia areata [3], dissecting cellulitis [4, 5], trichotillomania [6] and tinea capitis [4]. Black dots may be also detected in chemotherapy-induced alopecia [4], lichen planopilaris [7], discoid lupus erythematosus [7], traction
Yellow dots
Yellow dots correspond to follicular infundibula filled with sebum and/or keratotic material [10]. They present as yellow, or whitish, round or polycyclic dots, varied in size and uniformed in color, devoid of hairs or containing miniaturized, cadaverized or dystrophic hairs [10-12].
In alopecia areata, yellow dots are characterized by an abundant amount and regular distribution and predominate in long-lasting, inactive disease [3, 13].
The predominance of yellow dots (they are predominantly sebaceous) in the frontal area compared to the occipital area is characteristic for androgenetic alopecia [14]. They correspond to empty follicular openings of follicles in kenogen phase.
In discoid lupus erythematosus, large, dark yellow dots that correspond to wide infundibula filled with keratotic material are observed [1, 5].
Yellow dots, appearing as large "3D" soap bubbles imposed over dark dystrophic hairs are specific for dissecting cellulitis [1, 5].
Sparse yellow dots may also be detected in chronic telogen effluvium [8, 9], traumatic alopecia [8] traction alopecia [7], congenital hypotrichoses and kerion celsi [15].
Red dots
Red dots correspond to widened infundibula plugged by keratin and surrounded by dilated vessels and extravasated erythrocytes [16]. They are characteristic trichoscopic finding for active discoid lupus erythematosus and believed to be a positive prognostic factor [5].
White dots
There are two types of white dots.
The classic, big, irregular white dots correspond to areas of perifollicular fibrosis and are observed most commonly in lichen planopilaris [1].
The small, regular pinpoint white dots represent hair follicle openings and eccrine sweat gland openings and are observed in sun exposed areas and in dark skin phototypes regardless of hair loss [1].
