Trichoscopy in Alopecia Areata and Trichotillomania in Skin of Colour: A Comparative Study

Abstract

Alopecia areata (AA) and trichotillomania (TTM) are the two common causes of localised non scarring alopecia. While AA is an autoimmune disorder, TTM is an impulse control disorder which makes the treatment of the two entities completely different. Trichoscopy is a non-invasive tool used to diagnose hair disorders, which not only is extremely helpful in diagnosing AA and TTM but also differentiates them from other hair disorders as well. The aim of our study is to describe the various trichoscopic features of AA and TTM and to compare the frequency of each trichoscopic feature in order to establish diagnostic clues for differentiating AA and TTM. Trichoscopy was performed on clinically diagnosed cases of AA and TTM with DL4 dermoscope and the images were analysed by 2 dermatologists independently. The frequency of trichoscopic features in AA and TTM was compared using chi square test. Twenty-four patients of TTM and 50 patients of AA were included in the study with mean age of AA being 30 years and mean age of TTM being 23.4 years. Exclamation mark hair, tapered hair, coudability hair, pigtail hair, clustered vellous hair, clustered regrowing hair and white hair were significantly more in alopecia areata. Conversely broken hair of different length, trichoptilosis, flame hair, mace hair, coiled hair, hair powder, fractured hair, v sign and burnt matchstick sign were the common features in TTM. To conclude, even though there is an overlap of trichoscopic features in AA and TTM, it is possible to distinguish the two if an assemblage of specific features are present.

Introduction

Hair loss is one of the most common entities that presents routinely to any dermatology outpatient. Usually, the diagnosis is straightforward; however many a time, it needs a detailed history-taking and clinical examination to find the exact cause. In some cases, the diagnosis may not be forthcoming which may lead us to conduct a scalp biopsy and diagnose on the basis of histopathology. History-taking, especially in cases of trichotillomania (TTM), is challenging as it is difficult to build a rapport and the patient is usually hesitant to give a true history. Patchy non-scarring alopecia may pose a diagnostic challenge and trichoscopy helps a lot in these cases as it helps in reaching the diagnosis and, at the same time, avoiding any invasive investigations. Even though it has not replaced histopathology as the gold standard, with many trichoscopic studies now being done the existing repertoire of knowledge of trichoscopic features in alopecia is going to increase in the future. The aim of our study was to describe the various trichoscopic features of alopecia areata (AA) and TTM and compare the frequency of each trichoscopic feature in order to establish diagnostic clues for differentiating AA from TTM.

Materials and Methods

This multicentre study was conducted between December 2020 and February 2022 at the dermatology departments of six tertiary care hospitals with the aim to describe and compare the frequency of different trichoscopic features in TTM and AA. The regions and cities of the hospitals are as follows: Kochi (Kerala), Mumbai and Pune (Maharashtra), Kanpur (Uttar Pradesh), Bangalore (Karnataka) and Satwari (Jammu). Twenty-four patients of TTM and 50 patients of AA presenting to the outpatient department of multiple centres were examined with non-contact polarized light dermatoscope (DermLite DL4 × 10; 3 Gen, San Juan Capistrano, CA, USA), and images were captured using dermlite adaptor for Nikon D 3500. Only treatment-naive cases were considered in our study. Patients with any other scalp disease, such as seborrhoeic dermatitis, tinea capitis, androgenetic alopecia, etc., were excluded from our study. A blinded evaluation of trichoscopic findings was done by two dermatologists. The statistical analysis was done by GNU PSPP Statistical Analysis software version 1.4.1-g79ad47, 2019. Chi-squared test was used for statistical analysis and any P- value less than 0.05 was considered significant.

Results

The mean age of patients with TTM was 23.4 years with a male-to-female ratio of 1:3. Minimum age for TTM was 10 years while maximum presenting age was 64 years. The mean age of patients with AA was 30 years with a male-to-female ratio of 4:1. The trichoscopic features of all the patients are summarised in Table 1. We classified trichoscopic features as hair shaft and hair follicle opening features. Among hair shaft features, exclamation mark hair, tapered hair, coudability hair, pigtail hair, clustered vellus hair, clustered regrowing hair, and white hair were significantly more in AA (P < 0.05). Conversely, broken hair of different lengths, trichoptilosis, flame hair, mace hair, coiled hair, hair powder, fractured hair, V sign, and burnt matchstick sign were the common hair shaft features in TTM (P < 0.05). Black dots and yellow dots which were considered as part of hair follicle opening feature were higher in AA. On the other hand, perifollicular haemorrhage was significantly higher in TTM.

Table 1.

Frequency of trichoscopic features of TTM and AA in Indians

Trichoscopic features	Trichotillomania	Alopecia areata	P
Hair shaft features
Broken hair of different lengths	22 (92%)	5 (10%)	<0.0001
Trichoptilosis	16 (67%)	3 (6%)	<0.0001
Flame hair	12 (50%)	Nil	<0.0001
Fractured hair	4 (16%)	Nil	0.03
V sign	14 (58%)	4 (8%)	0.001
Broom hair	1 (4%)	Nil	0.14
Tulip hair	4 (16%)	8 (16%)	0.94
Coiled hair/hook hair/question mark hair	8 (33%)	Nil	0.001
I hair	2 (8%)	Nil	0.03
Exclamation mark hair / Tapered hair	2 (8%)	32 (64%)	0.0001
Clustered vellus hair	2 (8%)	40 (80%)	0.0001
Regrowing white hair	Nil	15 (30%)	0.003
Hair powder	6 (25%)	Nil	0.0002
Mace hair	8 (33%)	Nil	0.0001
Pigtail hair	2 (8%)	16 (32%)	0.02
Coudability hair	Nil	24 (48%)	0.0001
Regrowing hair	10 (42%)	42 (84%)	0.0002
Burnt matchstick sign	6 (25%)	Nil	0.0002
Hair follicle opening features
Black dots	14 (58%)	48 (96%)	0.0001
Yellow dots	2 (8%)	24 (48%)	0.0008
Perifollicular haemorrhage	6 (25%)	Nil	0.0002

Discussion

Alopecia areata and trichotillomania are common causes of non-scarring alopecia. AA is considered to be a chronic inflammatory disease with severity ranging from patchy hair loss to generalised loss of hair. Its worldwide lifetime incidence is around 2%.[1] In India, the reported incidence ranges from 0.7% to 3.8% in various studies.[2] The presentation ranges from patchy alopecia to very severe alopecia universalis. TTM is a form of traumatic alopecia in which there is an irresistible urge to pull one's own hair, leaving bizarre areas of hair loss. Its worldwide lifetime prevalence is 0.6%.[3] The patient's presentation ranges from small patchy alopecia to more severe tonsure pattern (also known as Friar tuck sign).[4] TTM, which was earlier considered as an impulse-control disorder, is now being considered in obsessive–compulsive-related disorder (OCRD) in the International Classification of Diseases (ICD-11) and Diagnostic and Statistical Manual of Mental Disorders (DSM-III). Similar disorders include trichotemnomania in which the patient has a compulsion of cutting hair, which may lead to alopecia, and trichoteiromania in which the patient rubs their hairs to produce patchy hair loss. In our study, we found one case of trichoteiromania.

Trichoscopy is an important non-invasive tool used to diagnose various scalp and hair disorders. It is useful not only in diagnosis but also serves as an important tool in post-treatment monitoring. AA, though a clinical diagnosis, may pose a diagnostic ambiguity with TTM, especially if AA is present as a solitary patch. This diagnostic dilemma can be solved to a great extent with the help of trichoscopy.

Exclamation mark hair which are short, uniformed, coloured hair with decreased thickness of proximal portion, and tapered hair, which are long exclamation hairs extending beyond the boundaries of dermoscope, are considered to be pathognomonic of AA [Figure 1a and b].[5] However, both of these features have been reported in TTM, post chemotherapy, in tinea capitis, anagen effluvium, and traction alopecia.[6,7,8,9,10] In our study, we found 64% of AA patients to have exclamation mark/tapered hair compared to 8% of TTM patients (P < 0.05). The exclamation mark/tapered hair present in TTM is supposed to be due to mechanical pull. Our results are comparable with the study conducted by Khunkhet et al.[11] in which 60% of patients of AA had exclamation mark hair while 24% of TTM patients had this finding.

Figure 1.

(a) Trichoscopy in a case of alopecia areata shows non-scarring alopecia with exclamation mark hairs (blue arrow) and regrowing white hair (red arrow) (b) Trichoscopy of alopecia areata showing exclamation mark hair (blue arrow) and coudability sign (red arrow) (DermLite DL4 × 10)

Coudability hairs are hairs which, when pushed inwards, show a kink towards the scalp. The hairs received their name in 1984 from Shuster as the ability of hair to bend/kink reminded the author of the coude catheter.[12] This was initially described as a clinical sign and can now be demonstrated dermoscopically as well. They have also been reported in radiation-induced alopecia.[13] In our study, 48% of patients ofs AA reported to have coudability hairs, whereas none of the TTM patients had this feature [Figures 1b and 2]. Various other terms have also been used for similar findings which include, but are not limited to, angulated hair, zigzag hair, and checkmark hair.[11]

Figure 2.

Trichoscopy of alopecia areata showing coudability hair (blue arrow), tulip hair (red arrow) and regrowing white hair (green arrow) (DermLite DL4 × 10)

Regrowing hairs are also common in AA. There can be various forms of regrowing hair which include upright, short regrowing hairs, regrowing vellus hair, regrowing white hair, and pigtail/circle hair [Figure 3]. All these are common in AA.[5,14,15] In our study, all the forms of regrowing hairs were statistically significant in AA. These findings are comparable to the findings by Khunkhet et al.[11] Short regrowing hairs have also been reported in TTM, tinea capitis, telogen effluvium, and temporal triangular alopecia.[16,17,18] Pigtail hair are short regrowing vellus hairs that are coiled inward. Pigtail hair should be differentiated from coiled hair and corkscrew hair which are broken hair that are contracted and coiled inwards. The coiled hairs are of uniform black colour and thickness as compared to pigtail hair which are thin and have decreased pigmentation. Coiled hair can assume the shape of a hook or a question mark, leading to different nomenclature. Coiled/hook/question mark hairs were seen only in TTM patients (33%) in our study [Figures 4 and 5]. In the study on trichoscopy of trichotillomania by Ankad et al.,[19] coiled hair was seen in 80% of TTM patients while Khunket et al.[11] reported this feature in only 4% of TTM cases.

Figure 3.

Trichoscopy of alopecia areata shows short regrowing hair (blue arrow), regrowing vellus hairs (black arrow), pigtail/circle hair (red circle), and black dots (red arrow) (DermLite DL4 × 10)

Figure 4.

Trichoscopy in a case of trichotillomania shows coiled hair (blue arrow), question mark hair (red arrow), hook hair (green arrow), broken hair of different lengths, and burnt matchstick sign (black arrow) (DermLite DL4 × 10)

Figure 5.

Trichoscopy in a case of trichotillomania shows broken hair of different lengths, black dots (green arrow), hair powder (blue arrow), coiled hair/question mark hair (red arrow), pigtail hair (red circle), and burnt matchstick sign (black arrow) (DermLite DL4 × 10)

Broken hair of different lengths (92%) and trichoptilosis (67%) were found to be much more common in TTM as compared to AA in our study [Figure 6]. These findings are comparable to the study by Khunkhet et al.[11] in which broken hairs of different lengths were present in 100% of TTM patients while trichoptilosis was seen in 78% of cases. If two hairs are broken at the same length, it is known as V-hair or V sign. We found V sign to be much more common in TTM (58%) as compared to AA (8%). This is comparable to findings by Khunkhet et al. who found V sign to be present in 43% of TTM patients as compared to 4% in AA.[11] V-hair was also found to be much more significant in TTM (58%) as compared to AA in a study by Rakowska et al.[16]

Figure 6.

Trichoscopy in a case of trichotillomania shows broken hair of different lengths, flame hair (red arrow), trichoptilosis (blue arrow), mace hair (yellow arrow), coiled hair (green arrow), circle hair/pigtail hair (red circle), and V sign (black arrow) (DermLite DL4 × 10)

Flame hair is considered to be wavy, semi-transparent, and conical hair residue that is formed due to traumatic pulling of anagen hair [Figure 6]. Flame hairs differ from hair powder—also described in TTM—by the presence of a hair shaft. Many authors consider it as a very specific marker of TTM; however, it has also been reported in a large number in acute chemotherapy- and radiotherapy-induced alopecia. Miteva et al.[20] reviewed the trichoscopic images of 454 patients with hair disorders and found flame hair in 100% of cases of acute chemotherapy- and radiotherapy-induced alopecia (out of 8 cases). They also found flame hairs in 55% of TTM cases (out of 20 cases), 21% of AA (out of 99 cases), 4% of traction alopecia (out of 86 cases), and 3% of central centrifugal cicatricial alopecia cases (out of 94 cases). The author suggested that flame hairs in this condition was due to anagen arrest caused by inflammation and drugs.[20] We found flame hair in 50% of TTM cases while none of the cases of AA showed any flame hair, which is comparable to findings by Khunkhet et al.[11] who found flame hair in 43% of TTM cases and no flame hair in any AA case.

Tulip hairs are short, light-coloured hair with darker tulip-shaped ends that develop when there is diagonal hair shaft fracture. In the study by Rakowska et al.,[16] 48% of TTM patients had tulip hairs (out of 44 cases) while 10% of AA patients also presented with tulip hairs (out of 314 cases). We found tulip hair in 16% of both TTM and AA cases [Figures 2 and 7].

Figure 7.

Trichoscopy in a case of trichotillomania shows multiple tulip hairs (yellow circle), i hair (blue circle), and trichoptilosis (red circle) (DermLite DL4 × 10)

Mace hairs are broken terminal hairs that are uniform in diameter and pigmentation and have a bulging distal end. Mace hair was initially described by Malakar et al.[21] It was also reported by Elmas et al.[22] in 45% of TTM cases (out of 20 cases). We found mace hair to be present in 33% of TTM cases while none of the AA cases had this finding [Figure 8].

Figure 8.

Trichoscopy in a case of trichotillomania shows mace hair (inset blue star), regrowing hairs, burnt matchstick sign (inset yellow star), perifollicular haemorrhage (blue arrow), and exclamation mark hairs (red arrow) (DermLite DL4 × 10)

Broom hairs are longitudinally split hair shafts of broken hairs. They reflect continuous frictional damage to the hair shaft. They are considered to be pathognomonic of trichoteiromania.[23] We had one case of trichoteiromania with multiple broom hairs [Figure 9].

Figure 9.

Trichoscopy shows black dots (green arrow), broom hairs (blue arrow), and flame hair (inset red arrow) with broken hair at different lengths in a case of trichoteiromania (DermLite DL4 × 10)

i hair was recently described by Malakar et al.[24] as a prognostic marker in both AA and TTM. The hair has bulbous and accentuated distal ends resembling the letter i. i hair is formed when black dot is pushed upward and the new hair forms the base. It has been mentioned as a good prognostic marker and a marker of recovery and treatment.[25] We could find i hair in two cases of TTM while none of our AA patients had this finding [Figure 7].

Burnt matchstick sign was reported in TTM cases by Malakar et al.[26] and is described as hair with dark bulbous proximal tip and linear stem of different lengths. We found this sign in 25% of TTM cases while none of the AA cases had it [Figure 10].

Figure 10.

Trichoscopy in a case of trichotillomania shows broken hair at different lengths, V sign (blue arrow), mace hair (red arrow), trichoptilosis (yellow arrow), coiled hair (blue star), and burnt matchstick sign (red star) (DermLite DL4 × 10)

Perifollicular haemorrhage was seen in 25% of TTM cases [Figure 8]. None of the patients with AA had this finding. This finding, though specific, is seen only if hair has recently been pulled. Many authors refer perifollicular haemorrhage as follicular microhaemorrhage.[27]

Black dots represent hair that is cut off at the surface. Black dots in AA are more uniform and regular as compared to TTM where they are more irregular, coarse, and non-uniform.[19] They have been considered as a characteristic marker of AA. However, they have been reported in numerous other hair and scalp disorders, which include but are not limited to TTM, tinea capitis, dissecting cellulitis, lichen planopilaris, discoid lupus erythematosus, traction alopecia, traumatic alopecia, and androgenetic alopecia.[28,29,30,31,32] We found black dots to be more common, numerous, uniform, and regular in AA (96%) compared to TTM (58%). Black dots can be confused with hair dust/powder of TTM. To differentiate between the two conditions Agrawal et al. proposed two new signs: halo sign and wipe-out sign. The halo sign is a trichoscopic feature that is represented by a greyish-white halo around the black dots due to the proximal, submerged part of the hair shaft that refracts polarized light through the epidermis. The wipe-out sign has been described as the ability to remove hair dust with a cotton bud.[33] We found halo sign in 14 AA patients [Figure 11].

Figure 11.

Trichoscopy in a case of alopecia areata shows yellow dots (red arrow), few black dots with halo sign (blue arrow), and broken hairs (green arrow) (DermLite DL4 × 10)

Yellow dots represent follicular infundibula filled either with sebum or with keratin. Sebum is seen in androgenetic alopecia while keratin is present in AA.[34] Multiple yellow dots in severe AA has been dubbed as craters-on-the-moon appearance.[35] Similar to black dots, yellow dots in TTM are sparse, irregularly distributed, and may contain black dot or black hair residue in the centre. We found 48% of cases with yellow dots while 8% of TTM cases had this finding [Figure 11].

There are various trichoscopic pointers that help in diagnosis of TTM and AA. However, there is a clear overlap of features. Hence, it is important to consider a variety of trichoscopic features together to be able to arrive at a diagnosis of AA or TTM. We have proposed specific trichoscopic features that will help in the diagnosis of AA and TTM in Indian skin [Table 2]. Our study enhances the existing repository of knowledge of trichoscopic features of AA and TTM which may aid in quick bedside diagnoses in the future and avoid invasive procedures.

Table 2.

Diagnostic clues for alopecia areata and trichotillomania in Indians

Alopecia areata	Trichotillomania
Exclamation mark hair/tapered hair	Broken hair of different length
Regrowing vellus and white hairs	Trichoptilosis
Pigtail hair	Flame hairs
Coudability hair	V sign
Regular, numerous black dots	Coiled hair/hook hair/question mark hair
Regular, numerous yellow dots	Mace hair
	Burnt matchstick sign hair
	Perifollicular haemorrhage

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.