Trichoscopy of Non-Cicatricial Alopecia.

MAIN FINDINGS

Alopecia areata
Micro-eclamation mark hairs, tapered hairs, black dots, yellow dots, upright regrowing hairs, pigtail regrowing hairs, vellus hairs and broken hairs.

Androgenetic alopecia
Increased proportion of thin and vellus hairs, hair shaft thickness heterogeneity, perifollicular discoloration (hiperpigmentation), and presence of variable number of yellow dots

Telogen effluvium
Upright regrowing hairs and predominance of hair follicle openings with only one emerging hair shaft.

Psoriasis 
Silver-white scales, red dots and globules, twisted red loops, and glomerular vessels.

Seborrheic dermatitis
Yellowish scales, arborizing vessels and atypical red vessels.

Tinea capitis
Comma hairs, corckscrew hairs, broken hairs, damaged hairs, black dots, zigzag hairs and interrupted hairs.


ALGORITHM

- Yellow dots: Numerous: Alopecia areata (AA)
                      A few:  Other alopecia: hypotrichosis congenita, Kerion celsie..
                                  Hair diameter diversity (≥20%), perifollicular pigmentation ⁄peripilar sign: AGA

- Black dots and/or broken hairs:  Tapering hairs (exclamation mark hairs): AA
                                                      Short vellus hairs: AA
                                                      Curled hairs: Trichotillomania                                               
                                                      No findings: AA and/or trichotillomania

                                                      Others: Tinea capitis, chemotherapy - induced alopecia, after laser depilation or trichogram.
- Others:  Perifollicular scale/sebum: Seborrheic alopecia
                Short vellus hairs, many: AA remitting
                Comma hairs: tinea capitis
                No findings: Telogen effluvium