Eponyms in Trichoscopy

Abstract

Trichoscopy is a non-invasive scalp and hair dermoscopy. In our daily dermatology practice, many eponyms are used. The present article highlights various eponyms in trichoscopy described in dermatology.

Introduction

Trichoscopy is a non-invasive technique used to view the hair and scalp structures at a higher magnification that reflects the pathophysiological changes of the skin and its appendages microscopically. It is based on the concept of dermoscopy and is used for diagnosing hair and scalp disorders.

The word 'eponym' is a noun that can be a person, place, or thing named after a person. In this article, we tried to enumerate such eponyms in trichoscopy.

Bamboo hair

It is characterized by an abnormal hair shaft that cloaks around a distal firmer shaft, generating multiple nodes along the hair shaft and is seen in trichorrhexis nodosa.[1]

Broom hair

It refers to the appearance of multiple thin, short hairs arising from a single follicular unit. They are seen in trichotillomania, and they may also be observed in both cicatricial and non-cicatricial types of alopecia.[2]

Brush-like stumps

It is characterized by increased fragility of hair as there is a focal longitudinal splitting of the shaft, resulting in the outer fibres to bulge and leading to nodes. It is seen in trichorrhexis nodosa. The nodes look like grey-white areas, and the classical paintbrush bristle appearance is seen on trichoscopy. In congenital cases, these nodes are present in the shaft's proximal part as against in acquired cases where they are present distally.[3]

Burnt matchstick sign

It is observed in trichotillomania, wherein due to tension created by constant pulling action, the proximal end becomes bulbous and dark, resembling a burnt match stick [Figure 1].[4]

Figure 1.

Burnt matchstick sign – Trichotillomania

Cherry blossom vascular pattern

It has been described in seborrheic dermatitis, which is an aggregation of arborizing vessels[5] that are larger vessels dividing into smaller and thinner branches in an uneven pattern.

Coudability sign

It is suggested as a disease activity marker in alopecia areata. It exhibits the terminal hair when pushed inwards toward the scalp; the proximal hair shaft, which is thinner, tends to kink [Figure 2].[6]

Figure 2.

Coudability sign – Alopecia areata

Corkscrew hair

Corkscrew hair is seen both in ectothrix and endothrix infections of tinea capitis. It is short hair, spirally shaped, and resembles a corkscrew [Figure 3].[7]

Figure 3.

Corkscrew hair – Tinea capitis

Comma hair

Comma hair is signified by partially bending of the hair shaft due to damage caused by ectothrix parasitization of fungal elements [Figure 4]. Corkscrew hair has multiple twists along its shaft, differentiating it from comma hair.[8]

Figure 4.

Comma hair – Ectothrix

Circle hair/Pigtail hair

Circle hair or pigtail hair is short, vellus hair that is thinned and coiled [Figure 5]. The large number of circle hair seen under trichoscopy is primarily diagnostic of alopecia areata.[9]

Figure 5.

Circle/Pigtail hair – Alopecia areata

Dandelion vascular conglomerate

The dandelion vascular conglomerate seen in seborrheic dermatitis is correlated to the high density of malassezia population. It appears as a yellow dot surrounded by glomerular and comma vessels.[5]

Eastern pancake sign

It is seen in alopecic and aseptic nodules of the scalp, where trichoscopic examination shows heterogeneously dilated follicular orifices.[10]

Exclamation mark hair

Exclamation mark hair is seen in alopecia areata,[3] and trichotillomania. It is characterized by the presence of short, broken hair with a hypopigmented, tapering proximal portion, and a darker, thicker distal portion [Figure 6].

Figure 6.

Exclamation mark hair – Alopecia areata

Flambeau sign

The linear tracks in continuation with the shaft of hair in traction alopecia, at one end giving the appearance of a flame or lit torch on trichoscopy, is called as Flambeau sign.[11]

Flame hair

Flame hairs are a type of hair residue that occurs due to severe external injury to the hair shaft after pulling anagen hairs [Figure 7]. It was first described by Rakowska et al.[12] as a trichoscopic sign seen in trichotillomania. They are also seen in fractional alopecia, central fibrosing alopecia, alopecia areata, and traction alopecia.

Figure 7.

Flame hair – Trichotillomania

Golf-tee appearance

In trichorrhexis invaginata, trichoscopy shows a hair shaft invaginates or telescopes into itself at various points along the shaft. At lower magnifications (i.e. handheld dermoscope), they may appear along the hair shaft as nodular structures. When the hair shaft fractures at the site of introversion, the proximal end will appear cupped. This kind of fractured hair is also known as golf-tee hair. Eyebrows are a favoured site to visualise this abnormality.[13]

Halo sign

A complete or arcuate greyish-white halo around the black dots is appreciable on trichoscopic examination due to the proximal submerged part of the hair shaft that refracts polarized light through the epidermis. This halo is not seen with hair powder, which is seen in trichotillomania.[14]

i hair

'i hair' are short hairs with an emphasized distal end (denoting the black dot) and a pale, skinny hypopigmented shaft just below the darker distal end, mirroring the letter i. i hair are modified black dots. As the disease process subsides in the course of time, the black dot grows into normal hair. It is seen in conditions like trichotillomania, alopecia areata, and tinea capitis.[15]

Mace hair

Mace hair is classically seen in trichotillomania,[16] where the broken hairs have bulged at the distal end with uniform hair shaft diameter and rough hair shaft [Figure 8].

Figure 8.

Mace hair – Trichotillomania

Morse code hair

In tinea capitis, the infected hair shaft shows multiple horizontal white bands [Figure 9]. These horizontal white bands seen are probably related to localized areas of fungal infection of vellus hair that gives a peculiar perforating fungal invasion as visualised on direct microscopy.[17]

Figure 9.

Morse code hair – Tinea capitis

Pink strawberry ice cream appearance

Big irregular white dots (classic), which merge into milky-red (strawberry ice cream colour) or white areas, are found in the fibrotic stage of lichen planopilaris.[18]

Peripilar sign

Brown hallow seen around the hair follicles in early stages of androgenetic alopecia is considered as peripilar sign, and it represents the early perifollicular inflammation.[6]

Question mark sign

After pulling from the skin, the circle hairs show a typical question mark appearance, which, whenever released, lowers back to its original position with a partially or fully recoiled shape. They show a 'river bed' dilated follicular infundibula with hair shafts entrapped on histopathological examination. They show in anagen phase dystrophic bulb, absence of inner root sheath, and thinning of distal hair shaft leading to the circular track.[19]

Regular bended ribbon sign

Trichoscopy in monelithrix reveals the characteristic beaded appearance of the hair. They show bending in different directions and tend to break at internodes revealing the regularly bended ribbon sign [Figures 10 and 11].[20]

Figure 10.

Ribbon sign – Monelithrix

Figure 11.

Beaded hairs – Monilethrix like in congenital hypotrichosis

Starburst sign

Large follicular pustules with emerging hair shafts, tufted hairs, and perifollicular starburst pattern hyperplasia are seen in individuals with folliculitis decalvans.[4]

Soap bubble dots

In dissecting cellulitis, the characteristic yellow dots have a three-dimensional appearance, resembling soap bubbles, with or without hair shafts. Such structures strongly suggest the active phase of dissecting cellulitis and are not seen in other non-cicatricial or cicatricial forms of alopecia.[21]

Tadpole hair

The regrowing phase of the hair follicle in alopecia areata shows a tadpole-like structure.[22]

Tulip hair

Tulip hairs are characterized by short hairs with darker, tulip flower shaped ends [Figure 12]. They develop when hair shafts are fractured diagonally.[23]

Figure 12.

Tulip hairs – Diagonally fractured hair shaft

V Sign

The 'V' sign represents two hairs that were pulled at the same time and snapped off at the surface [Figure 13]. They are found in well over 50% of patients with trichotillomania.[24]

Figure 13.

V sign – Trichotillomania

Wipe-out sign

The hair powder seen in trichotillomania can be wiped out with the help of a cotton bud, as they are due to the fragmentation of intact hair, whereas the same does not hold in the case of hair dust. This sign is called a 'wipe-out sign'.[14]

Zig zag hair

It is signified by hairs that are bent at multiple sharp angles. Their formation occurs due to incomplete, transverse fractures along the hair shaft. It was first described by Rudnicka et al.[25] They are seen in fungal infection (ectothrix-type) and has also been reported in alopecia areata.

Conclusion

We see here that there are several eponyms in trichoscopy, and as a dermatologist, it would be imperative to know how they present to arrive at a conclusive diagnosis and follow-up and for better therapeutic outcomes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.