|SYMPOSIUM: BASICS OF DERMOSCOPY AND DERMOSCOPIC PATTERNS
|Year : 2020 | Volume
| Issue : 2 | Page : 102-114
Trichoscopy in hair disorders in darker skin: An approach to diagnosis
Balachandra S Ankad1, Samipa Mukherjee2, SV Smitha1
1 Department of Dermatology, S Nijalingappa Medical College, Bagalkot, Karnataka, India
2 Department of Pediatric Dermatology, Cloudnine Hospital, Bengaluru, Karnataka, India
|Date of Submission||15-May-2020|
|Date of Decision||26-Jun-2020|
|Date of Acceptance||02-Jul-2020|
|Date of Web Publication||18-Aug-2020|
Balachandra S Ankad
Department of Dermatology, S Nijalingappa Medical College, Navanagar, Bagalkot - 587 102, Karnataka
Source of Support: None, Conflict of Interest: None
Introduction: Trichoscopy is a non-invasive technique that shows promising results in the diagnosis and assessment of response to treatment in various types of alopecias. Besides diagnosing alopecia, it is helpful in choosing an ideal biopsy site. Here authors have attempted to describe trichoscopic findings of healthy scalp and compare hair shaft abnormalities, follicular and interfollicular features and vascular patterns of common non-cicatricial and cicatricial alopecias in skin of color.
Summary: Trichoscopy of androgenetic alopecia shows hair diameter diversity, brown and white peripilar sign. Exclamatory hairs and coudability hairs are characteristics of alopecia areata. 'i' hair and pigtail hair indicates good prognosis in alopecia areata. Mace hair sign and burnt matchstick sign are newer findings of trichotillomania. Tinea capitis shows comma hairs, corkscrew hairs. Morse-code like hairs, zigzag hairs and bent hair are specific for tinea capitis. Traction alopecia shows anisotrichosis and hair casts with follicular drop outs in severe disease. Trichoteiromania shows trichoptilosis and broom hairs. Lichen planopilaris (LPP) and discoid lupus erythematosus show 'targetoid' and speckled patterns of blue-grey dots respectively. Perifollicular tubular scaling is characteristic in LPP. Frontal fibrosing alopecia presents as absent follicular openings and follicular plugging. Follicular tufting with starburst fibrotic bands is definitive of folliculitis decalvans. Pseudopelade of Brocq presents with loss of follicular ostia with prominent honeycomb pigmentation.
Keywords: Trichoscopy, dark skin, hair shaft, follicles, patterns
|How to cite this article:|
Ankad BS, Mukherjee S, Smitha S V. Trichoscopy in hair disorders in darker skin: An approach to diagnosis. Clin Dermatol Rev 2020;4:102-14
| Introduction|| |
Trichoscopy is the application of a dermatoscope to directly visualize the scalp and hair, facilitating closer look into the affected areas and determine the etiology, activity, prognosis, and response to treatment in various hair and scalp disorders. In 2006, Lidia Rudnicka and Malgorzata Olszewska coined the term “Trichoscopy” for dermoscopy of hair and the scalp. For the trichoscopic study of hair disorders manual handheld dermatoscopes (×10) to video dermatoscopes (×20 to × 1000) have been used.
To determine what is abnormal one must know first what is normal. An attempt has been made to encompass a step-by-step approach in the diagnosis of common noncicatricial and cicatricial alopecias in skin of color.
Dermoscopy of normal healthy scalp shows follicular units containing 2–4 terminal hairs, 1–2 vellus hairs, honeycomb pigment, follicular, and eccrine openings and fine loops of capillaries [Figure 1]. The step-by-step approach in trichoscopy is based on trichoscopic patterns: (a) Hair shaft characteristics; specific and nonspecific hair shaft changes observed in mechanical, hereditary and inflammatory conditions, (b) follicular patterns; white dots, yellow dots, black dots and red dots, (c) interfollicular patterns; pigmentary and background patterns, and (d) vascular patterns.
|Figure 1: Trichoscopic image of normal scalp showing 2–5 terminal hairs (yellow arrows) per follicular unit (yellow circle) with few vellus hairs (red arrow) and eccrine and follicular white dots (green arrows). Honeycomb pigment network is well appreciated|
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- Terminal hair – Uniformly pigmented with normal and consistent diameter [Figure 2]a
- Vellus hair – Hypopigmented with reduced diameter measuring <3 mm [Figure 2]b
- Miniaturized hair – Normally pigmented with reduced diameter [Figure 2]c
- Regrowing hair – (i) Upright regrowing hairs; short hair with uniform color and tapered distal end [Figure 2]d (ii) Short vellus hairs (pigtail hairs; vide infra)
- Exclamation mark hair – Short hair with uniform color with reduced thickness in proximal portion [Figure 2]e
- Tapered hair – Long exclamation mark hair that extends beyond the field of the dermoscope [Figure 2]f
- Broken hair – Terminal hair which is broken in midway [Figure 2]g
- Pigtail hair (circle hair) – Short vellus hair that is coiled inward and attached to scalp [Figure 3]a
- Coudability hair – Tapered hair with thinning of proximal portion that kink toward the scalp when pushed inwards vertically [Figure 3]b
- Coiled hair – Broken hair that is contracted and coiled inward due to constant pull and has uniform color and thickness (compare with circle hair)
- Black dot – Hair shaft remnant of a hair that is cut at surface level
- Red dots – Nonblanchable concentric dots around follicular ostia due to extravasation of erythrocytes [Figure 3]c
- Yellow dots – Polycyclic irregular yellow globular structures on the scalp due to dilated follicles. They are difficult to appreciate in dark skin where they may even appear as white dots [Figure 3]d
- White dots – (i) Pinpoint white dots of eccrine and follicular openings [Figure 3]e
- “i” hair – Hair that resemble the English letter “i” [Figure 3]f
- Flame hair – Semi-transparent, wavy, and cone-shaped hair [Figure 3]g
- Mace hair – Normal pigmented hair with bulbous distal end [Figure 4]a
- Tulip hair – Hypopigmented hair with pigmentation only at the tip [Figure 4]b
- Morse code-like hair – Normal hair which is interrupted by regular and multiple white bands [Figure 4]c
- Corkscrew hair – Normal pigmented hair which is circled itself resembling a coil [Figure 4]d
- Zigzag hair – Normal pigmented which is bent acutely at multiple points in the shaft [Figure 4]e
- Comma hair – Normal pigmented hair that appears as English letter “C” [Figure 4]f
- V-hair: Two normal pigmented hairs that emerge from a single follicular ostium [Figure 4]g
|Figure 2: Schematic diagram shows terminal hair (a), vellous hair (b), miniaturized hair (c), upright regrowing hair (d), exclamation mark hair (e), tapered hair (f), and broken hair (g)|
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|Figure 3: Schematic diagram shows pigtail or circle hair (a), coudability hair (b), red dots around yellow and white follicular plugs (c), yellow dots (d), white dots (e), “i” hair (f) and flame hair (g)|
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|Figure 4: Schematic diagram shows mace hair (a), tulip hair (b), Morse code-like hair (c), corkscrew hair (d), zigzag hair (e), comma hair (f), and V-hair (g)|
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| Noncicatricial Alopecia|| |
Androgenetic alopecia (AGA) is characterized by the miniaturization and reduced density of hairs. The prime sites of trichoscopic examination in AGA are frontal, temporal, vertex, and occipital area. Although occipital area is not affected, it is examined for comparison. Trichoscopy in AGA reveals hair diameter diversity or hair shaft thickness heterogeneity of more than >40% in males and >40% in females. This is suggestive of vellus hair transformation of terminal hairs and it is the hallmark of AGA [Figure 5]a. Follicular changes in AGA include white dots, yellow dots, brown peripilar sign (BPPS), white peripilar sign (WPPS), and focal atrichia.,
|Figure 5:(a) Trichoscopy of androgenetic alopecia shows numerous miniaturized hairs (blue arrow), few terminal hairs (yellow arrow) and vellus hairs (red arrow). Note the single hair is emerging form a follicular opening and hair diameter heterogeneity. Honeycomb pigment pattern and white dots are well appreciated. (b) Trichoscopy of androgenetic alopecia in early stage shows peripilar brown halo (red arrows), numerous miniaturized hairs (blue arrow) and terminal hairs (yellow arrow). Note the single hair is emerging form a follicular opening. Honeycomb pigment pattern, diameter heterogeneity, and white dots are well appreciated. (c) Trichoscopy of androgenetic alopecia in advanced stage shows peripilar white halo (maroon arrows), numerous miniaturized hairs (blue arrow), and terminal hairs (yellow arrow). Note the honeycomb pigmentation, diameter diversity, and pinpoint white dots. (d) Schematic diagram shows eccrine white dots (i) and follicular white dots (ii). Eccrine white dot is surrounded by reticular pigment network whereas in follicular white dot is devoid of it (e) Trichoscopy of alopecia areata shows black dots (red arrows), coudability hairs (yellow arrows), short vellus hairs (blue arrows), and trichoptilosis (purple arrow). Note the exclamation mark hairs (green arrows) and tapered hairs (maroon arrows). (f) Trichoscopy of alopecia areata shows upright regrowing hair (red arrows) and yellow dots (blue arrows). Honeycomb pigment network is well appreciated. (g) Trichoscopy of alopecia areata shows pigtail hairs (yellow arrows), black dots (green arrows), coudability hairs (maroon arrow), exclamation mark hairs (blue arrows), and broken hairs (red arrows). Honeycomb pigment network is well appreciated. (h) Trichoscopy of alopecia areata shows yellow dots with central black dot (red arrows) and without dark dot (maroon arrows), few upright regrowing hairs (blue arrows), and short vellus (pigtail) hairs (green arrow). Note the polycyclic and irregular nature of yellow dots and honeycomb pigmentation|
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BPPS is subtle brown depressed halo, seen in early stages and reflects perifollicular micro inflammation. It measures around 1 mm and is a specific finding, in skin of color it looks as grayish-brown or whitish-brown [Figure 5]b.WPPS is whitish halo around the follicle that is bigger than BPPS and it is observed in severe grades of AGA [Figure 5]c., White dots are well preserved. Eccrine white dots (0.2 to 0.3 mm) are uniform in size and shape and are equidistant. Follicular white dots are irregular, larger and nonuniform in size and shape. Former dots are surrounded by reticular pigment network whereas latter are devoid of pigment network [Figure 5]d. Probable histological basis for this; outer layer of infundibulum is continuous with basal layer showing only the outer pigmented rim while eccrine duct is surrounded by normal pigment network. However, further speculations are warranted in this regard. Yellow dots are difficult to appreciate and require higher magnification to visualize. However, a careful observation allows visualization of yellow dots in skin of color with manual dermoscope. They consist predominantly of sebum which is in contrast to the yellow dots in alopecia areata (AA) wherein they have keratin material. Specifically, the presence of four or more yellow dots on four trichoscopic fields in the frontal region is one of the major trichoscopic criteria for the diagnosis of female AGA alopecia. The pigmentary pattern shows normal honeycomb pigmentation with no significant vascular patterns.
The trichoscopy finding in AA depends on the stage, site, severity, and activity of the disease. It is ideal to examine the periphery of the patch and then move to central area since the disease activity is higher at the periphery.
Exclamation mark hairs are characterized by thinning of proximal portion with uniform pigmentation all along the hair shaft. They are suggestive of active disease and are noted at the margin of alopecic patch [Figure 5]e., Long exclamation mark hairs are referred to as “tapered hairs.” When tapered hairs are pushed inward towards scalp hair kinks and this striking feature is known as “coudability sign” and the hairs are “coudability hairs” [Figure 5]e. Nevertheless, “coudability hairs” and exclamation mark hairs are not specific to AA. Broken hairs suggest the pathological process involving fracture of the hair shaft. Other hair shaft abnormalities include “i” hairs and pigtail hairs. The “i” hairs were basically described in tinea capitis (TC). However, it is reported that “i” hairs are observed in AA and TTM. These are short hair with an accentuated distal end and a thin hypopigmented shaft just beneath the darker distal end, resembling the alphabet “i.” The “i” hair is formed when black dot is pushed upward (on treatment) so that dot of the letter “i” is basically black dot and lower stem of the letter indicates the new hair shaft. Thus, “i” hair is indicative of good prognosis.
Two types of regrowing hairs are noted in AA namely short vellus hairs and upright regrowing hairs. Former hair is thin and less pigmented while latter one is pigmented upright with a tapered distal end [Figure 5]f. Short vellus hairs are sometimes circled inward and attached to the scalp and are referred to as “pigtail” hairs or “circle” hairs [Figure 5]g. Large number of circle hair on trichoscopy is almost diagnostic of AA. Both types of hair represent the success of the treatment.
Follicular patterns include black dots and yellow dots [Figure 5]h. Black dots are characteristic of AA but they are found in trichotillomania (TTM) and TC. In AA, they are regular, fine and uniform. In TTM, they are irregular, crude, coarse, and nonuniform. Black dots are milder and lesser in count in TC. In AA, black dots are sensitive indicators of disease activity and severity. Yellow dots are seen in all the stages of the disease and correlate with disease severity. They are relatively regular in distribution. As stated above, yellow dots in AA contain keratin and in AGA they have sebum. Numerous yellow dots in severe AA give “craters in the moon” appearance. Pinpoint white dots, single or in groups are conspicuously noted in darker skin types. In sub-totalis AA, multiple white dots coalesce into a bigger white area that produces “cotton wool” appearance., Honeycomb pigment network is preserved in the interfollicular region. Vascular patterns are note observed routinely in AA. However, it can sometimes give a clue toward treatment; overuse of topical steroids or intralesional steroid injections.
Alopecia areata incognita
AA incognita is a variant of AA which presents with diffuse, acute loss of telogen hairs in the absence of typical patches. While the clinical picture resembles that of telogen effluvium (TE), trichoscopic and histopathological findings classically represents AA features. Trichoscopy reveals diffuse, round or polycyclic yellow dots, which vary in size but uniform in color and distribution. Yellow dots are present in both empty and hair-bearing follicles. Trichoscopic features of AA such as regrowing hairs, tapered hairs, and exclamation mark hairs can be seen which directs toward the proper mode of treatment.
It is a disease of entire scalp unlike AGA and AA. Trichoscopy of TE shows decreased hair density with the presence of empty follicles. However, these findings are not specific for TE. The presence of upright regrowing hairs and predominance of hair follicle openings with only one emerging hair shaft may be indicative of TE in absence of features characteristic for other causes of hair loss. On trichoscopy, TE is a diagnosis of exclusion and more emphasis should be given for patient's history for accurate diagnosis.
There is a trichoscopy-based scoring tool called AA predictive score (AAPS) which helps to predict treatment response in patients with AA. It is based on change in positive markers like upright regrowing hair and pigtail hair and negative markers such as black dots, broken hairs, exclamation mark hairs, and tapered hair trichoscopically before and after treatment. The AAPS ranges between 4 and 2 with higher scores reflective of better prognosis for hair regrowth.
Trichoscopic findings in TTM are characteristic and include decreased hair density and hairs broken at different lengths [Figure 6]a. The pulling force in TTM results in the loss of cuticle, shaft fracture, breakage, and contracture of hair shaft. Consequently, flame hairs, tulip hairs, coiled hair, mace hair, broken hair, and hair powder are observed that are diagnostic.,,, “Flame hairs” are semi-transparent, wavy and cone-shaped hair residues not present in other types of hair loss, thus specific for TTM [Figure 6]b. Trichoptilosis or “split ends” is the splitting or fraying of distal hair shaft due to excessive heat and mechanical stress. It is common as hair gets longer and is usually pathological if it is found in short hair as in case of TTM.
|Figure 6:(a) Trichoscopy of trichotillomania shows broken hairs with different length (yellow arrows), black dots (red arrows) and “burnt match stick” hairs (blue arrows). (b) Trichoscopy of trichotillomania shows flame hairs (yellow arrows), black dots (red arrows), and trichoptilosis (blue arrows). Note the crude, irregular, and flamboyant nature of black dots. (c) Trichoscopy of trichotillomania shows tulip hairs (arrows) and hair powder (stars) in the interfollicular area. Note the reduced hair density and black dots. (d) Trichoscopy of trichotillomania shows coiled hairs that are contracted and attached to the scalp (yellow arrows) with question mark hairs (red arrow) and hook hairs (blue arrows). Note the perifollicular hemorrhages (green arrow). (e) Trichoscopy of trichotillomania shows mace hair (yellow arrow) with multiple broken hairs and white dots. (f) Trichoscopy of tinea capitis shows comma hairs (yellow arrows), broken hairs (red arrows), and “i” hairs (blue arrows). Note the milder characteristics of black dots (green arrows). (g) Trichoscopy of tinea capitis reveals multiple corkscrew hairs (yellow arrows) which are circled inward with few comma hairs (red arrow). Note the uniform pigmentation all along the shaft. (h) Trichoscopy of tinea capitis shows multiple Morse code-like hairs (yellow arrows), perifollicular scales (red arrows), and perifollicular hemorrhages (blue arrows). Brownish discoloration is well appreciated in majority of the Morse code-like hairs. (i) Trichoscopy of tinea capitis reveals multiple zigzag hairs (red arrows) and bent hairs (blue arrows). Few Morse code-like hairs (green arrows) are noted|
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These are marker of severe disease. Tulip hairs are due to diagonal fracture of hair shaft and are short hairs having thin, transparent proximal shaft with darker tip resembling a tulip flower [Figure 6]c. They are characteristic for TTM but may be found in AA.,
Exclamation mark hairs are observed in TTM too. Distal end is flat in TTM and it is uneven (frayed) and ragged in AA. It is noteworthy that both types of exclamation mark hairs are observed in both AA and TTM. In such situations, other trichoscopic features should be considered to establish accurate trichoscopic diagnosis. Coiled hairs are fractured, short hairs that are fixed to scalp with a contraction and have splits at distal end. The partially coiled hairs appear either as “question mark” or “hook hair” [Figure 6]d.V-hair or V-sign is referred to two hairs emerging from a single follicular opening broken at the same level.
Recently, a peculiar “mace” hair is described that is a broken terminal hair with uniform diameter and pigmentation with a bulge at distal end. It is due to structural damage because of constant pull and a bulge at distal end could be due to splaying and flattening [Figure 6]e. Another new feature in TTM is “burnt matchstick” sign [Figure 4]b. Here, hair has a dark bulbar proximal tip with a linear uniformly pigmented stem of variable length. This results from trauma and traction of hair which gives the appearance of a burnt matchstick [Figure 6]a. As mentioned above, “i” hairs, if present in TTM, are good prognostic sign and they reassure positive treatment response. Follicular patterns show black dots which are coarse and irregularly distributed [Figure 6]b. Their distinction from the black dots that are observed in AA (vide supra) is important., Yellow dots are subtle and not observed conspicuously in TTM as compared to AGA or AA.
Perifollicular hemorrhages once thought to be specific for TTM has now been associated with multiple pruritic conditions of the scalp, less obvious in darker skin [Figure 6]d.,, Hair powder, residue of damaged hair and keratin debris from the fractured shaft can be noticed as sprinklings in perifollicular area [Figure 6]c. This is also specific to TTM. Pigmentary pattern generally remains unperturbed. Various patterns in terms of hair shaft, follicles, interfollicular area, and vasculature in noncicatricial alopecia are shown through a trichoscopic approach in [Table 1].
| Tinea Capitis|| |
Trichoscopic examination of the hair shafts in TC shows various morphological changes. The most characteristic and definitive trichoscopic changes in TC include comma hairs, corkscrew hairs, zig-zag hairs, Morse code-like hairs, bent hairs, and block hairs.
Comma hair is short hair which appears as comma punctuation mark. It is homogeneous in color and thickness. It results from cracking and bending of shaft due to fungal invasion [Figure 6]f., Occasionally, they may be found in AA and TTM. Corkscrew hairs are multiple twisted and coiled hairs with corkscrew-like structure [Figure 6]g. These are predominantly noted with Trichophyton and Microsporum species.
Morse code-like hairs, also known as bar code-like hairs, are due to perforation of shaft by the fungal spores. This produces multiple white bands across the shaft. They are also specific to TC. In higher magnification, white bands appear as translucent areas representing fungal colonies. In author's experience, color of Morse code-like hair is brown rather black in most of the hairs [Figure 6]h. Zigzag hairs explain the structure of hair that is bent acutely in different angles. They resemble letter “Z” [Figure 6]i. Bent hairs are described as bending of hairs that are uniformly homogeneous in color and diameter [Figure 6]i. Morse code-like, zigzag, and bent hairs are specific to TC and noted specifically in ectothrix type. Block hairs are terminal broken hairs when distal end is cut/fractured transverse and horizontal. As mentioned earlier, the “i” hairs [Figure 6]f and broken hairs are noted in TC also. After treatment with antifungals, cigarette-ash shaped hairs are noticed. In the course of treatment, the corkscrew hair shaft became more incompact and more easily broken as the endothrix spores were eliminated by the antifungal treatment.
Follicular changes include black [Figure 6]f and yellow dots. Black dots are less common whereas yellow dots are rare. Perifollicular and interfollicular scales [Figure 6]h are characteristically seen in TC which is in contrast to AA and TTM. Perifollicular hemorrhagic spots [Figure 6]h or areas are uncommonly seen as in TTM. The pigmentary and vascular patterns are not of much help in diagnosis.
Congenital triangular alopecia
Congenital triangular alopecia (CTA), also called temporal triangular alopecia, is a congenital disorder of the scalp showing patchy hair loss predominantly on the temporal area but can be present elsewhere on the scalp demonstrating a carpet of vellus hair on trichoscopy.
Hence, in trichoscopic approach, hair shaft abnormalities include short vellus hairs, hair length diversity in vellus hairs. Tufts of vellus hairs are occasionally found. Follicular structures include white dots with slight perifollicular scaling. Honeycomb pattern pigmentation and arborizing vessels are observed in interfollicular area [Figure 7]a. Exclamation mark hairs or tapered hairs, yellow dots, black dots, or loss of follicular openings are not observed in CTA.
|Figure 7: (a) Trichoscopy of congenital triangular alopecia shows carpet of vellous hairs (yellow arrows) with white dots and linear vessels (red arrow). (b) Trichoscopy of traction alopecia shows numerous vellous hairs that are emerging in single (yellow arrows) or in groups from a follicular ostium. Note the pinpoint white dots (red arrows) suggestive of early phase of disease. (c) Trichoscopy of traction alopecia in late phase shows vellus hairs (yellow arrows), broken hairs (red arrows), black dots (maroon arrows), and circle hair (green arrow). Note the white dots are replaced by patches (yellow stars). Brownish rings (blue arrows) are well appreciated. (d) Trichoscopy of trichoteiromania shows hairs with longitudinal splits resulting in broom hairs (yellow arrows). Lichenoid change is seen as brownish halo around follicles (red arrows). Note the conspicuous absence of black, yellow, or white dots. (e) Trichoscopy of lichen planopilaris shows loss of follicular ostia, perifollicular cast (yellow arrows), and pinpoint white dots. “Targetoid” pattern of blue-gray dots (red arrows) around follicular openings is well appreciated. (f) Trichoscopy of lichen planopilaris in late stage shows loss of follicular ostia, white patches (yellow stars) and blue-gray dots (red arrows). Note the pili torti seen as twisted hair shaft (yellow arrow). Linear vessels are indicative of topical steroid application. (g) Trichoscopy of lichen planopilaris in early stage shows multiple white dots (red arrows) on honeycomb pigmentation (yellow star) giving a “starry sky” pattern. Peripilar casts (yellow arrows) and subtle pinkish hue are well appreciated|
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Traction alopecia refers to temporary (often permanent) hair loss caused by prolonged physical damage. Various shaft abnormalities include miniaturized hairs, vellus hairs, hair casts, circle hairs, and broken hairs with different lengths of hair.
Both miniaturized and vellus hairs have reduced hair thickness. Anisotrichosis analogs to AGA is observed. Single vellus hair in single follicle is noted in advancing disease [Figure 7]b.
Broken hairs with different length similar to TTM, is characteristic. Nevertheless, flame hairs, coiled hairs, or hair powder is absent in TA. Regrowing circular hairs are attributed to intact follicles.
Hair cast is important finding in TA and in many hair diseases as well. In TA, they are noted mainly in the margin of the patch and are yellowish-white or grayish-white cylindrical encasings with 2–7 mm long size, easily movable along the shaft in the proximal portion. They indicate of ongoing process of mechanical traction and progression of disease course.,
Since TA complicates into permanent hair loss, it is mandatory to look for the hair casts in a suspicious lesion of TA to initiate therapy to prevent the permanent hair loss.
Follicular changes include white dots and black dots. Brownish ring surrounding follicular ostia is a striking feature [Figure 7]c. This correlates with epidermal pigmentation and is conspicuous in skin of color.
Regular distribution of white dots is observed in early phase of the condition which implies intact follicular ostia. The initiation of treatment at this moment would halt disease progression and result in regrowth of hairs. In advanced phase, dots coalesce to form white patches which represent “follicular drop out” and fibrous fibrotic tracks in histopathology. It is almost like a cicatricial alopecia. This trichoscopic observation reinforces the biphasic nature of TA; initially a noncicatricial alopecia with intact follicular openings (pinpoint white dots) which turns into a cicatricial alopecia with loss of follicular openings (irregular white areas).
Interfollicular area shows honeycomb pigmentation which is a conspicuous trichoscopic pattern in skin of color. Arborizing vessels are noted in few cases.
Trichoteiromania is a process of fracturing of hair shafts due to repeated rubbing of the scalp. It is considered as a self-inflicted hair disorder. Authors proposed the term trichoteiromania: “tricho” means hairs; “teiro” means “I rub” and mania means “urge.” The characteristic trichoscopic pattern is trichoptilosis with longitudinal splits at distal end. These are called as “broom hairs” – the splits are of same length from distal to proximal, resembling a broom. Scaling, erythema, atrophy, and white, black or yellow dots are strikingly absent.
However, in chronic cases, lichenoid changes are expected on scalp. Multiple splits affecting many hair shafts give the appearance of clusters of broom hairs [Figure 7]d.
It is should be noted that trichoscopy of trichoteiromania does not reveal hair changes that are observed in TTM such as flame, coiled, mace, and V-hairs. It is largely because of constant rubbing of hairs in trichoteiromania hairs rather than pulling of hairs (in TTM). Various patterns in terms of hair shaft, follicles, interfollicular area, and vasculature in noncicatricial alopecia are shown through a trichoscopic approach in [Table 2].
| Cicatricial Alopecia|| |
Trichoscopy in lichen planopilaris (LPP) demonstrates distinctive patterns.
Hair shaft abnormalities include reduced hair density, peripilar casts, broken hairs, tufted hairs, and pili torti. Occasionally, short regrowing hair as pigtail hair is found., Reduced hair density is typified by absence of follicular openings in affected area. Peripilar casts, also known as “tubular scales” (Collar sign) result from the follicular hyperkeratosis [Figure 7]e. Scales are characteristically adherent to shaft and typically climb a little along the proximal portion of shaft. This is in contrast to hair casts in TA wherein they move easily. Peripilar casts bespeak disease activity. Broken hairs at the margin of alopecic patch illustrate ongoing pathological process. Pili torti is a feature of congenital hair disorders in which regular twists in hair shaft at irregular intervals are seen. Rarely, it is found in LPP [Figure 7]f and frontal fibrosing alopecia (FFA)., A meticulous look with handheld dermoscope is paramount to visualize pili torti.
Follicular changes are white dots and white areas or patches with perifollicular blue-gray dots., White dots situated amidst honeycomb pigment pattern give a “starry sky” pattern [Figure 7]g in early phase whereas white areas or patches [Figure 7]f correlate with fibrous fibrotic tracks of scarred follicles found in chronic cases. Perifollicular blue-gray dots pursue a specific “targetoid” pattern [Figure 7]e that correlates histopathologically to perifollicular melanophages in dermis. This is unique to LPP and discriminates from discoid lupus erythematosus (DLE). Interfollicular area shows honeycomb pattern of pigment network.
Vascular elements reveal erythema and milky-red areas in the perifollicular and interfollicular areas, respectively, in different stages of the disease process. Perifollicular erythema can be seen in LPP but it is difficult to appreciate in skin of color.
Discoid lupus erythematosus
Trichoscopy in DLE establishes various patterns based on the stage of the disease. In early lesions, shaft abnormalities include reduced hair density, broken hairs, a single hair in follicular ostia, trichoptilosis and tufted hairs [Figure 8]a. Follicular ostia are dilated with plugs which may be yellowish or whitish [Figure 8]a. They denote hyperkeratosis and keratotic plugs.
|Figure 8: (a) Trichoscopy of discoid lupus erythematosus in early lesion shows a single hair emerging in a follicular ostium (yellow arrows), trichoptilosis (red arrows), and tuft of hairs (green arrow). Note the yellowish plugs (blue arrows), perifollicular red dots (maroon arrows) with white scales. (b) Trichoscopy of discoid lupus erythematosus in late lesion reveals pinkish-white background (yellow stars), thin telangiectasia (blue arrows), and interfollicular blue-gray dots (yellow arrows). White rosettes (blue circles) consisting of four white shiny globules are well appreciated. (c) Trichoscopy of discoid lupus erythematosus reveals whitish-brown areas (red stars) with perifollicular (yellow arrows) and interfollicular (red arrows) blue-gray globules. Note the honeycomb pigment pattern (black stars). (d) Trichoscopy of frontal fibrosing alopecia shows loss of follicular ostia, lonely hair (yellow arrow), and mild perifollicular erythema (yellow star) (Image courtesy: Dr Yasmeen Bhat, GMC, Srinagar, India). (e) Trichoscopic image of folliculitis decalvans shows perifollicular yellowish tubular scale (red arrow), tufted hairs (yellow arrows) with perifollicular and interfollicular white scales (red stars). Note the white fibrotic bands radiating from the follicle (yellow star). Honeycomb pattern (green star) and brownish areas (blue stars) are well appreciated. (f) Trichoscopic image of pseudopelade of Brocq shows prominent honeycomb pigment pattern with loss of follicular ostia|
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Red dots in DLE are most emphasizing feature in active lesions [Figure 8]a. They are light red to dark red, polycyclic, concentric with regular alignment around the follicular ostia. Number varies from 50 to 100 with a size of <1 mm. Importantly, “follicular red pattern” is not influenced by pressure effect. They are attributed to vasodilatation and extravasation of erythrocytes. Another striking pattern in DLE is “white rosettes” which represent four oval-shaped whitish structures oriented together at a center point [Figure 8]b. The optical phenomenon of polarization in the follicular and perifollicular structures results in white rosettes. Notably, white rosettes are not found in other cicatricial alopecias.
Interfollicular area shows reddish or pinkish-white background with focal bluish areas. In skin of color, focal brownish or whitish dyschromia with bluish hue are observed [Figure 8]c. Minimal and focal white scales are noted in interfollicular area. Vascular structures are thick arborizing vessels situated around the follicle and in interfollicular areas. It is important to note that the diameter of thickened vessels is more than that of surrounding terminal hair. Reddish hue, arborizing vessels, and follicular red pattern validate active inflammation and warrant immunosuppressive therapy to avert permanent hair loss. Recently, bluish-white veil is described as novel feature in DLE. This corresponds to acanthosis and compact orthokeratosis.
In chronic lesions, milky-red or white patches and absence of follicular ostia with few large yellow dots may be noted [Figure 8]b. Sprinkles of bluish-gray dots and brown areas are seen. Bluish-gray dots are arranged in “speckled” pattern [Figure 8]c in peri- and interfollicular area in contrast to “targetoid” distribution in LPP. Thin arborizing vessels can be found. No follicular red dots and white rosettes are seen.
Frontal fibrosing alopecia
Recession of frontotemporal hairline and absence of follicular ostia are hallmark features in FFA. Trichoscopically, the characteristic absence of follicular openings, follicular hyperkeratosis and plugging, perifollicular scaling, and erythema are noted. Shaft abnormalities include broken hairs, short vellus hairs, and pili torti. Follicular plugging appears as white roundish structures and represents follicular hyperkeratosis. Occasionally, it may contain a central black dot denoting a remnant of hair shaft. Uncommonly, yellow dots and black dots can be found in FFA.
Perifollicular white scales around the ostia are observed. They are circular and do not climb the shaft in a tubular fashion unlike in LPP (vie supra). Perifollicular erythema is another distinctive feature that is seen in evolving phase of disease activity thus mandates immediate intervention. Similarly, the absence of cicatricial white patches suggests active disease [Figure 8]d.,, Interfollicular area shows honeycomb pigment pattern which is obviously apparent in skin of color. Interfollicular erythema is very difficult to appreciate in skin of color because of prominent pigmentation due to melanized basal layer. Interestingly, FFA on eyebrows shows yellow dots, multiple pinpoint white dots, vellus hairs, black dots, and tapering hairs. These features are seen in non-cicatricial alopecia. Hence, trichoscopy in FFA on eyebrows is not similar to that of scalp. One should be aware of this entity to obviate misdiagnosis. We can differentiate traction alopecia from FFA by the presence of anisotrichosis and brown ring around follicular ostia in the former.
Various patterns in terms of hair shaft, follicles, interfollicular area, and vasculature in cicatricial alopecia are shown through a trichoscopic approach in [Table 3].
The hallmark of folliculitis decalvans (FD) is presence of tuft of hairs (multiple hairs emerging from a single dilated follicular opening). Follicular tufts consist of 5–20 hairs [Figure 8]e, below 5 hairs being considered as normal. As in other cicatricial alopecias; regrowing hairs, broken hairs, vellus hairs, and pili torti are observed in FD. Occasionally, peripilar cast is noted.
Yellow dots, black dots, and fibrotic white dots with significant absence of follicular ostia are the follicular structural changes. White perifollicular scaling is noted. Yellowish tubular scales, perifollicular pustules, and crusting are the distinctive patterns of FD. These patterns are not observed in other cicatricial alopecias except in dissecting cellulitis of the scalp. In long standing cases, whitish fibrotic bands are largely noted. They are arranged in a “starburst” pattern [Figure 8]e.
Interfollicular area shows pinkish-white and yellowish structureless areas. In the perspective of skin of color, honeycomb pigment pattern and brownish areas are prominent. Vascular elements are not usually appreciated in FD.
Dissecting cellulitis of scalp
Dissecting cellulitis of scalp (DCS) illustrates heterogeneity in trichoscopy. Many features are overlapping and many are not specific to ascertain diagnosis of DCS. Although rare clinical entity, trichoscopic examination is crucial to prevent progress of disease and to rule out other cicatricial alopecias. It shows broken hairs, exclamation mark hairs and circle hairs with tufted hairs. Exclamation mark hairs are seen in early phase. Tufting of hair is less frequent as compared to FD.
Follicular structures include yellow, black, white, brown, and blue-gray dots. Yellow dots are most characteristic of DCS and are described as “3D” or soap bubble yellow dots. These are large and have double borders as compared to yellow dots that are found in other hair diseases. They confer the irreversible stage of disease. Large brown dots which correspond to comedones are noted this trichoscopic feature relates DCS to acne-related conditions. Occasionally, black dots and blue-gray dots are noted. White dots are noted in early phase and white fibrotic patches are seen in late stage. Yellow area in interfollicular area representing lakes of pus is a distinctive feature of DCS. Perifollicular pustules and crusting is noted in early lesions. Dotted and arborizing vessels can be seen.
| Pseudopelade of Brocq|| |
Trichoscopic features of classic pseudopelade of Brocq are nonspecific and include loss of follicular ostia, ivory-white areas and occasionally solitary dystrophic hairs at the periphery of the lesion [Figure 8]f. It is considered as a diagnosis of exclusion both clinically and dermoscopically. Occasionally, short vellus hairs and pili torti are seen as shaft abnormalities with pinpoint white dots and white fibrotic white dots which are referred to as ivory-white areas. Interfollicular area shows prominent honeycomb pigment pattern in skin of color whereas in skin types I, II, and III it appears as pinkish-white area. No vascular structures are seen., Various patterns in terms of hair shaft, follicles, interfollicular area, and vasculature in cicatricial alopecia are shown through a trichoscopic approach in [Table 4].
To conclude, trichoscopy serves as a rapid, noninvasive diagnostic tool when posed with a diagnostic dilemma aiding not only in the diagnosis but also in prognosticating the disease, assessing larger areas of involvement and evaluating treatment response through serial examinations in succeeding visits.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2], [Table 3], [Table 4]