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Keywords:

  • alopecia areata;
  • androgenetic alopecia;
  • cicatricial alopecia;
  • trichoscopy;
  • trichotillomania

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Alopecia areata
  5. Androgenetic alopecia
  6. Cicatricial alopecia
  7. Algorithmic method for trichoscopic diagnosis of common hair loss diseases
  8. References

In recent years, the usefulness of trichoscopy (scalp dermoscopy) has been reported for hair loss diseases. Here, characteristic trichoscopic features of common hair loss diseases are described using a DermLite II pro or Epilight eight. Characteristic trichoscopic features of alopecia areata are black dots, tapering hairs (exclamation mark hairs), broken hairs, yellow dots and short vellus hairs. In androgenetic alopecia (AGA), hair diameter diversity (HDD), perifollicular pigmentation/peripilar sign and yellow dots are trichoscopically observed. In all cases of AGA and female AGA, HDD more than 20%, which corresponds to vellus transformation, can be seen. In cicatricial alopecia (CA), the loss of orifices, a hallmark of CA, and the associated changes including perifollicular erythema or scale and hair tufting were observed. Finally, an algorithmic method for trichoscopic diagnosing is proposed.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Alopecia areata
  5. Androgenetic alopecia
  6. Cicatricial alopecia
  7. Algorithmic method for trichoscopic diagnosis of common hair loss diseases
  8. References

In recent years, the usefulness of trichoscopy (scalp dermoscopy)1 has been reported for hair loss diseases. Here, characteristic trichoscopic features of common hair loss diseases are described using a DermLite II pro (3Gen, San Juan Capistrano, CA, USA) or Epilight eight (Ondeko, Tokyo, Japan) and an algorithmic method for trichoscopic diagnosing is proposed.

Alopecia areata

  1. Top of page
  2. Abstract
  3. Introduction
  4. Alopecia areata
  5. Androgenetic alopecia
  6. Cicatricial alopecia
  7. Algorithmic method for trichoscopic diagnosis of common hair loss diseases
  8. References

Characteristic trichoscopic features of alopecia areata (AA) are black dots, tapering hairs (exclamation mark hairs), broken hairs, yellow dots and short vellus hairs2–4 (Fig. 1). Among these, the black dots, tapering hairs and broken hairs are known as pathognomonic hairs of AA.

image

Figure 1.  Trichoscopic findings in alopecia areata: (a) black dots, (b) tapering hairs (exclamation mark hairs), (c) coudability hairs, (d) broken hairs, (e) yellow dots, (f) short vellus hairs.

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The black dots (Fig. 1a), seen in 44.3% of the 300 case series, positively correlate with disease activity and severity4 but can be seen also in trichotillomania, which should be noted for differential diagnosis of AA. In addition, as similar features, “comma hairs” are observed in tinea capitis.5 The tapering hairs (Fig. 1b), corresponding to rapid catagen induction in AA, are seen in 31.7%,4 providing an indicator for disease activity. This category contains “coudability hairs” (Fig. 1c),6 normal-looking hairs tapered at the proximal aspect, which were previously reported as another sign of AA.7 The broken hairs (Fig. 1d) are encountered in 45.7% of the 300 case series and positively correlated with disease activity4 while they can be seen in trichotillomania. The yellow dots (Fig. 1e), first reported by Ross et al.,2 are considered to be a mixture of immature hair shaft and sebum.3 The previous study suggested that they positively correlate with AA severity and have a tendency of positive correlation with AA activity.4 As a diagnostic marker, the yellow dots are sensitive but not specific because they can be seen in other hair loss diseases including androgenetic alopecia (AGA) (Fig. 3c), hypotrichosis congenita (Fig. 2a) and kerion celsi (Fig. 2b). The clustered short vellus hairs (Fig. 1f) shorter than 10 mm, seen in 44.3% of the series of the 300 cases, negatively correlated with disease activity and severity.4 They can be observed on seemingly complete hair loss areas, providing a sensitive diagnostic marker for AA. Indeed, either yellow dots or short vellus hairs are seen in 94% of AA.4

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Figure 3.  Trichoscopic findings in androgenetic alopecia. (a) Hair diameter diversity, (b) perifollicular pigmentation/peripilar sign, (c) yellow dots (arrowhead).

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image

Figure 2.  Yellow dots in (a) hypotrichosis congenita and (b) kerion celsi.

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Androgenetic alopecia

  1. Top of page
  2. Abstract
  3. Introduction
  4. Alopecia areata
  5. Androgenetic alopecia
  6. Cicatricial alopecia
  7. Algorithmic method for trichoscopic diagnosis of common hair loss diseases
  8. References

In AGA, hair diameter diversity (HDD), perifollicular pigmentation/peripilar sign and yellow dots are trichoscopically observed. In all cases of AGA and female AGA (FAGA), HDD more than 20%, which corresponds to vellus transformation,8,9 can be seen (Fig. 3a), providing a useful hallmark to diagnose early AGA. However, hereditary hypotrichosis simplex (HHS), a rare autosomal dominant form of hair loss characterized by hair follicle miniaturization, must be considered10,11 in cases of young patients with HDD. To rule out HHS, the recent finding of a mutation (Leu9Arg) in the adenomatosis polyposis downregulated 1 (APCDD1) gene in HHS is useful.11 The perifollicular pigmentation/peripilar sign (Fig. 3b) was first described by Deloche et al.12 and in their report all cases of AGA showed this sign in white but in Asian patients only 66% (33/50) showed it, ascribing the discrepancy to interference by skin color.9 Yellow dots (Fig. 3c) are seen in 26% (13/50) of AGA patients and their number was up to 10 on the whole scalp while yellow dots in AA are more numerous.

Cicatricial alopecia

  1. Top of page
  2. Abstract
  3. Introduction
  4. Alopecia areata
  5. Androgenetic alopecia
  6. Cicatricial alopecia
  7. Algorithmic method for trichoscopic diagnosis of common hair loss diseases
  8. References

In cicatricial alopecia (CA), the loss of orifices (Fig. 4a), a hallmark of CA and the associated changes including perifollicular erythema or scale and hair tufting (Fig. 4b) were observed.13,14 Hair tufting can be seen in CA such as folliculitis decarvans/tufted folliculitis, acne keloidalis, dissecting cellulitis of the scalp, kerion celsi and lichen planopilaris.15 Further, Tosti et al.16 have recently reported that the follicular red dot pattern is a specific feature of active lupus erythematosus of the scalp.

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Figure 4.  Trichoscopic findings in cicatricial alopecia. (a) Loss of orifices in frontal fibrosing alopecia, (b) hair tufting in folliculitis decarvans.

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Algorithmic method for trichoscopic diagnosis of common hair loss diseases

  1. Top of page
  2. Abstract
  3. Introduction
  4. Alopecia areata
  5. Androgenetic alopecia
  6. Cicatricial alopecia
  7. Algorithmic method for trichoscopic diagnosis of common hair loss diseases
  8. References

Based on previous reports and observations, herein, an algorithmic method for trichoscopic diagnosis of common hair loss diseases is proposed (Fig. 5). In the clinical practice, diagnosis should be comprehensively made from clinical appearance and trichoscopy. When these findings are not consistent, biopsy should be considered. Because this scheme deals with typical cases of a limited range of hair loss diseases, it will be revised hereafter.

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Figure 5.  Algorithmic method for trichoscopic diagnosis of common hair loss diseases. *The activity of alopecia areata is estimated by the ratio of pathognomonic hairs/short vellus hairs. **In trichotillomania, curled hairs, caused by strong pulls, are often seen. ***Seborrheic alopecia can be diagnosed by the perifollicular scale and sebum in hair follicles more than 10 in annular zones with approximate 2.5-cm diameters. BD, black dots; BH, broken hairs; DLE, discoid lupus erythematosus; SVH, short vellus hairs; TH, tapering hairs.

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References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Alopecia areata
  5. Androgenetic alopecia
  6. Cicatricial alopecia
  7. Algorithmic method for trichoscopic diagnosis of common hair loss diseases
  8. References