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suprapapillary epidermis3. Follicular units in normal scalp contain 2 to 4 terminal hairs and 1 or 2 vellus hairs inside. Particles of dirt, dust, loose fibers and other.
Review Article

Dermoscopy in Hair Disorders Antonella Tosti, M.D.* and Bruna Duque-Estrada, M.D.† *Department of Dermatology, University of Bologna, Bologna, Italy and †Instituto de Dermatologia Prof. Rubem David Azulay, Rio de Janeiro, Brazil. Hair loss can have significant effects on patients’ quality of life, and a prompt diagnosis of the different types of alopecias and an early intervention is needed. This review highlights the main dermoscopic findings in the different types of alopecia, as androgenetic alopecia, alopecia areata, trichotillomania, lichen planopilaris and discoid lupus erythematosus of the scalp. We believe that this important tool has demonstrated to help dermatologists in finding the right site for the biopsy, or furthermore avoiding unnecessary biopsies. Through photograph assessment, follow up of patients is also best appreciated at each visit. (J Egypt Women Dermatol Soc 2010; 7: 1 - 4) Keywords. Dermoscopy, alopecia, trichotillomania, lichen planopilaris, discoid lupus erythematosus

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air style is a human characteristic that may represent aspects of identity, ethnic group and health. Hair loss can have significant effects on patients’ quality of life and a prompt diagnosis of the different types of alopecias and an early intervention is worthful when dealing with those patients. The standard methods to diagnose hair and scalp disorders as simple clinical inspection, pull test and biopsy vary in reproducibility and invasiveness and there is a need for non invasive methods that help the clinician in the everyday practice. The use of dermoscopy improves diagnostic accuracy and may contribute in understanding the pathogenesis of hair disorders1,2. For scalp examination, dermatologists can use a manual dermoscope (x10 magnification) or a videodermoscope equipped with various lenses (from x20 to x1000 magnification). Dermoscopy findings include vascular patterns, follicular and perifollicular signs and hair shaft characteristics. Examination of the normal scalp can show simple fine red loops that represent capillary loops in the dermal papilla1. In dark skinned individuals, a perifollicular pigmented network (honeycomb pattern) is well appreciated. The network consists of hyperchromic lines that represent melanocytes in the rete ridge system in contrast with hypochromic areas formed by few melanocytes localized in the suprapapillary epidermis3. Follicular units in normal scalp contain 2 to 4 terminal hairs and 1 or 2 vellus hairs inside. Particles of dirt, dust, loose fibers and other small particulate debris that we defined dirty dots, may be appreciated in children between 1 and 12 years old. These particles disappear immediately

after shampooing to reappear as soon as 24 hours afterwards4 . In scalp psoriasis, within the typical scaly plaques, twisted red loops are observed at higher magnification (x70) (Figure 1). Twisted loops are also seen to a limited extent in unaffected psoriatic scalp as well as in newly treated psoriatic scalp. There is a direct correlation between the morphology of the loop and the state of the overlying epidermis and twisted loops occur in conditions of epidermal hypertrophy with a psoriasiform pattern. In seborrheic dermatitis, arborizing red lines, which have a wider caliber than the loops, can be observed. This may be helpful in the differentiation of these two scaly conditions. However, capillary loop density seems to be similar in patients with psoriasis, seborrheic dermatitis and healthy scalp skin, and sometimes twisted loops are observed in sebopsoriasis-like forms of seborrheic dermatitis1,5,6.

Corresponding Author. Antonella Tosti, M.D., Department of Dermatology, University of Bologna, Italy. E-mail. antonella.tosti@ unibo.it

Conflict of interest. None declared. Copyright © 2009 Egyptian Women Dermatologic Society. All rights reserved.

Figure 1. A typical scaly psoriatic plaque with numerous twisted red loops observed in the scalp.

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Dermoscopy in Hair Disorders

In alopecia areata, yellow dots are very characteristic and have been seen in over 95% of European patients. In Asian patients, yellow dots are present in 60% of cases7 and in the authors’ experience in Brazil, this finding is present in about 40% of cases. These dots represent follicular openings filled with keratinous debris mixed with sebum (Figure 2). We believe that the differences regarding the frequency of this finding are due to skin phototypes, as well as different shampoo habits between European, Asian and Latin American cultures.

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Alopecia areata incognita is a variety of alopecia areata that mimics androgenetic alopecia and telogen effluvium with development of diffuse and severe hair thinning in few months. Under dermoscopy, yellow dots are evident within the follicular ostium of both empty and hair-bearing follicles in about 70% of the follicles and a large number of regrowing, tapered, terminal hairs are evident in the entire scalp (Figure 4)9,10.

Figure 4. Alopecia areata incognita. Yellow dots can be observed within the follicular ostium of both empty and hair-bearing follicles. Figure 2. Alopecia areata. Numerous pink to yellow dots arranged in groups of two to three dots along the alopecic patch.

Visualization of classic findings of active disease as dystrophic hairs, exclamation mark hairs and cadaverized hairs are improved beyond simple clinical inspection, as well as regrowth of vellus hairs (Figure 3)1,2. Recently, Inui et al.7 showed that for diagnosis, yellow dots and short vellus hairs were the most sensitive markers, and black dots, tapering hairs and broken hairs were the most specific markers of the disease. Black dots, tapering hairs, and broken hairs correlated positively with disease activity. Multiple depressed follicular ostia may be observed under dry dermoscopy. It has been suggested that these represent abnormal hair follicles containing incompletely differentiated hair shafts8.

Figure 3. Alopecia areata. Black dots are observed inside the yellow dots and represent cadaverized hairs that are broken before emergence from scalp.

Dermoscopy findings are also important to differentiate trichotillomania from alopecia areata. In the first, hairs are broken at different distances from the scalp and longitudinal splitting of hair shafts can also be seen11,12. Androgenetic alopecia is characterized by hair diameter diversity due to miniaturization of the hair follicles. Variability in hair shafts diameter of more than 20% is diagnostic of this condition (Figure 5)13. In early androgenetic alopecia, it is common to see peripilar brown depressions described as peripilar signs14. In patients with advanced androgenetic alopecia, yellow dots can be observed and the sun-exposed scalp often show the honeycomb pigment pattern.

Figure 5. A variability in the hair shaft diameter of more than 20% of hair shafts is diagnostic of androgenetic alopecia. J Egypt Women Dermatol Soc. Vol. 7, No. 1, 2010

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Antonella Tosti and Bruna Duque-Estrada

Videodermoscopy allows measurement and monitoring of hair shaft thickness in androgenetic alopecia, where it may also help in calculating the terminal to vellus hair ratio2,15. Under higher magnifications on videodermsocopy, it is possible to identify and count vellus hairs (with less than 0.03 mm in width)11,15. It is worthwhile to note that follicular ostia in androgenetic alopecia show predominance of single hairs, instead of 2-4 hair shafts observed in normal subjects15. Primary cicatricial alopecias are a large group of disorders characterized by permanent destruction of the hair follicle. All, presumably, result from irreversible injury of the stem-cell-rich bulge area, which is required for the cyclic regeneration of the lower follicle16. One of the hallmark features is absence of follicular ostia and the presence of fibrous tracts that mark extinct follicles on pathology, as observed by Kossard and Zagarella3. In lichen planopilaris (LPP), dermoscopy reveals absence of follicular openings and the presence of characteristic perifollicular scales (peripilar casts) at the periphery of the patch. Perifollicular erythema characterized by the presence of arborizing vessels around the follicular ostia is also observed (Figure 6).

Figure 6. Lichen planopilaris. Perifolicular erythema and hyperkeratosis is well appreciated in this case, as well as discrete pigmented network. Absence of follicular ostia and terminal hair follicles are also evident inside the alopecic plaque.

A pigmented network is well appreciated in dark-skinned individuals inside the plaques of hair loss.17 As interfollicular epidermis is commonly unaffected by the inflammatory process in LPP, we believe that this sign may help in differentiating this type of alopecia from other scarring alopecias, as discoid lupus erythematosus of the scalp. White pale dots distributed between the pigmented network were reported by Kossard and Zagarella3 in a dark-skinned patient as a hallmark of extinct follicles. The focal decrease in the pigmentation of the rete ridges above the fibrous tracts probably accounts for the pale color seen clinically. J Egypt Women Dermatol Soc. Vol. 7, No. 1, 2010

Blue-grey dots may be found in some patients, especially those with dark skin. A peculiar pattern of round perifollicular blue-grey dots “target pattern” may be observed in some dark patients with LPP. Histopathologically, these dots are caused by loose melanin, fine melanin particles or melanin ‘dust’ in melanophages or free in the deep papillary or reticular dermis. The “target pattern” is associated with the presence of melanophages predominantly around hair follicles, sparing interfollicular epidermis17. Usually, LPP spares some terminal hair follicles inside the alopecic patches. In frontal fibrosing alopecia, a clinical variant of lichen planopilaris, the most prominent dermoscopic findings are loss of follicular openings, peripilar scale and peripilar erythema18. In discoid lupus erythematosus (DLE), affected scalp shows erythema, scaling, follicular plugging, atrophy and telangiectasias. Despite the fact that is considered as part of the group of cicatricial alopecias, DLE may show hair regrowth if promptly treated. In this way, early diagnosis is important for patients’ prognosis. Under dermoscopy, scalp atrophy is represented by a diffuse white color of the scalp. This pattern is well appreciated in dark-skinned patients, who loose the normally seen pigmented network within the lesion17. Indeed, the honeycomb pigmented network might be seen at the periphery of the plaque of DLE. Arborizing and tortuous vessels are the most common vascular patterns seen inside DLE plaques. A peculiar finding of red to pink-red, round and polycyclic dots that are uniform in size and regularly distributed around follicular openings may be also observed. Hyperkeratotic follicular pluggings are observed in the follicles around the patches. Blue-grey dots may be observed, with a diffuse and speckled pattern of distribution along the patch17. These dots represent pigmentary incontinence in the papillary dermis of follicular and interfollicular epidermis. We believe that the different patterns of blue-grey dots described may be an interesting feature to help dermoscopic differentiation between DLE and LPP. In conclusion, dermoscopy has shown to be an important tool in the evaluation and diagnosis of patients with alopecia as a first step before performing a biopsy. It can even help dermatologists in finding the right site for the biopsy, or furthermore avoiding unnecessary biopsies. Through photograph assessment, follow up of patients is also best appreciated at each visit.

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J Egypt Women Dermatol Soc. Vol. 7, No. 1, 2010