Trichoscopy in alopecias: diagnosis simplified

Abstract

Trichoscopy is the term coined for dermoscopic imaging of the scalp and hair. This novel diagnostic technique, both simple and non-invasive, can be used as a handy bed side tool for diagnosing common hair and scalp disorders. Trichoscopic observations can be broadly grouped as hair signs, vascular patterns, pigment patterns and interfollicular patterns. In this article, we have briefly described the trichoscopic findings in the common categories of cicatricial and non-cicatricial alopecias such as androgenetic alopecia, alopecia areata, telogen effluvium, tinea capitis, trichotillomania, lichen planopilaris, discoid lupus erythematosus and hair shaft disorders. Besides diagnosing alopecia, it has the potential for obviating unnecessary biopsies and when a biopsy is still needed it is helpful in choosing an ideal biopsy site. Moreover, trichoscopy is a valuable tool for evaluating the treatment response photographically at each follow-up. The last statement here is deleted as asked.

Keywords: Alopecia areata; androgenetic alopecia; dermoscopy; diagnosis; discoid lupus erythematosus; lichen planopilaris; telogen effluvium; tinea capitis; trichoscopy; trichotillomania.

Figure 1

Follicular units in normal scalp contain 2-4 terminal hairs and 1 or 2 vellus hairs inside. A homogenous pigment pattern is usually present

Figure 2

Characteristic yellow dots seen in alopecia areata. Exclamation hair (tapered hair) is also seen

Figure 3

Multiple white dots (blue arrows), interspersed with eccrine duct openings, seen as well-defined regularly placed hypopigmented dots (black arrows). Some follicles show fractured hairs

Figure 4a

Multiple black dots seen in alopecia areata, representative of fractured dystrophic and telogen hairs. Furthermore note the homogenous honey comb pigment pattern in the background

Figure 5a

Androgenetic alopecia. Sparse follicles with significant hair shaft diameter variation and predominance of single hair bearing follicles

Figure 5b

A case of advanced androgenetic alopecia with pearly white dots. These represent hypertrophied sebaceous glands

Figure 5c

Peripilar halo seen as brown depressions. This sign is seen in early androgenetic alopecia and marks perifollicular inflammation

Figure 4b

Alopecia areata. Dermoscopy shows Exclamation mark hairs, Black dots and fractured hair shafts (cadaverized hair)

Figure 4c

Coudability sign in alopecia areata, seen as a kink or a sharp bend of the terminal hair shaft

Figure 6

Tinea capitis: Black dots with scaling and blotchy pigmentation pattern are visible

Figure 7

Trichotillomania. Hair shafts of variable length seen. Signs of excessive traction like longitudinal splitting of hair shafts and coiling of hairs are seen

Figure 8

Lichen planopilaris. Peripilar tubular casts (scales) with pigment incontinence seen (target ‘blue-grey dots’)

Figure 9

Discoid lupus erythematosus. Atrophy and complete follicular paucity with arborizing telangiectasia and scaling. Also characteristic hyperkeratotic plugs seen

Figure 10

Monilethrix. Beaded hair shaft with regularly spaced nodes and internodes (‘regularly bended ribbon’ sign) are seen

Figure 11

Trichorrhexis nodosa. Dermoscopy shows brush like hair fractures and fraying at nodes

Chart 1

Algorithmic approach towards the diagnosis of alopecia based on trichoscopy.[18] AI - Alopecia incognito