Pityriasis amiantacea had yellowish concretions forming thick, matted bundles holding the hairs together resembling amianth or asbestos (Fig. 10). In chemical burn cases and short anagen syndrome, dermoscopy was nonspecific, although the latter showed numerous upright regrowing hairs of different lengths with pointed distal tips (Figs 11 and 12).
Androgenetic alopecia patients revealed hair diameter diversity in the affected areas with vellus hair more than 20% and the presence of single hair follicles (Fig. 13). Folliculitis decalvans and acne keloidalis showed follicular tufts, perifollicular erythema, crusts, and pustules (Figs 14 and 15). Clinical examination was important to differentiate between these two diseases.
Ectodermal dysplasia patients on dermoscopy had sparse hair. Most follicular units contain one hair. Hair shafts bend in different directions at irregular intervals with diversity of pigmentation and pili torti (Figs 16 and 17). The nevus sebaceous patient revealed a yellow–orange plaque with warty appearance (Fig. 18).
Although scalp disorders and hair loss cause no physical disabilities in most cases, cosmetic concerns can be problematic, especially in children 6. The precise and reliable diagnosis of hair growth disorders, based on the clinical experience and trichological knowledge of the dermatologist, is necessary for a successful therapeutic and cosmetic management strategy 3.
Few studies concerning the use of dermoscopy in the study of hair disease exclusively on children were found 7. Therefore, the aim of this study was to shed light on the causes of hair loss among a group of Egyptian children and to determine the frequent dermoscopic pattern of each disease.
Hair loss in children in this study accounted for 11.3% of children visiting the Dermatology Outpatient Clinic of MUST Hospital during 1 year. This higher percentage compared with another study 8, which reported an incidence of 3%, may be due to the increased number of fungal infections in Egypt.
Tinea capitis showed the highest percentage (30.2%) among the cases, which is nearly similar to a study in Jordan that reported tinea capitis in 40% of cases 9. Ali et al.10 reported that tinea capitis is the most common cause of patchy hair loss among children in the developing world. A warm humid climate, overcrowdedness, and poor sanitary conditions augment the spread of this infection 11. Moreover, the direct contact with animals in rural areas is a potential source of infection 12.
In this study, the gray patch was the most common type, followed by the black dot, favus, and kerion; similar findings have been reported by others 13,14. In contrast, in another study 15, black dot was the major clinical type, followed by the gray patch and kerion. This difference could be attributed to race, culture, nutrition, or climate conditions.
In this study, tinea capitis was more common in male (N=48) than in female patients (N=29), with a ratio of 1.6 : 1; this is similar to the 2 : 1 ratio in Kenya and the 1.8 : 1 ratio in Rajasthan 16. This high prevalence among boys was explained by their short hair, the rarely disinfected barbing instruments, exchange of caps, and rubbing of the hair during play 17.
The dermoscopic characteristic findings of tinea capitis, the comma hair and corkscrew hair, were found in 36 (46.7%) and 30 (38.9%) patients, respectively, in this study. Other studies described comma hair in two (of two patients), seven (of seven patients), and eleven (55%) patients with tinea capitis 18–20. In addition to the comma hair sign, the corkscrew hair was seen in four black children (66.7%) and nine (45%) children with tinea capitis 21,20; dystrophic and broken hairs were also noted.
Rudnicka et al.22showed interrupted (Morse code-like) hairs in patients with tinea capitis, which was also observed by other studies 23–25. In the present study, this Morse code-like (bar code-like) hair was seen in 11.7% of the cases. The bar code-like hair has been reported to be a specific dermoscopic feature of fungal infection of the scalp and eyebrow due to perforation of the hair cuticle by fungal hyphae 23.
Traction alopecia in this study was present in 16.9% of cases and all cases were female. Similar results were reported showing 20% prevalence 9. The high percentage was explained by the common habit of traction of hair in the Arab environment to keep the hair of girls tightened with rubber bands or clips, which add more traction.
In this study, dermoscopy revealed hair thinning in all traction alopecia patients, hair casts in 62.8%, yellow dots, black dots, erythema, and crusts. Tosti et al.26 detected hair casts in 100% of their studied cases. Rudnicka et al.27 reported early features such as perifollicular erythema, hair thinning, focal decrease in hair density with retained follicular markings, or ostia and mentioned that hair casts is one of the pathognomonic features of traction alopecia. The presence of hair casts can give the clinician a clue in the differential diagnosis of alopecia affecting the scalp margin 28.
Dermoscopy allows a rapid and reliable diagnosis of pediculosis by identification of lice or nits fixed to the hair shaft 29. Pediculosis capitis may present with a number of atypical presentations, including hypersensitivity reactions, erosions, impetigo, cervical lymphadenopathy, and malaise 30. Circumscribed and patchy alopecia has been rarely described. This was attributed to the combination of chronic scratching secondary to the inflammation related to relatively long-standing pediculosis that might lead to hair loss and the broken hairs seen on examination 31.
Patients with pediculosis in this study complained of diffuse hair loss. The pull test was positive in most cases. More than half (56.4%) had impetigo that may have added to the inflammation related to pediculosis, with the secondary pruritus, causing the hair loss and the broken hairs seen in 82% of the patients. Pediculosis was considered a precipitating factor for diffuse hair loss in one patient in another study 32. Further studies with larger numbers are needed to determine whether pediculosis can cause diffuse hair loss, which may be a presenting clinical sign.
Alopecia areata is a common disease ranging from 0.7 to 3.8% of patients attending dermatology clinics 33, with pediatric alopecia areata constituting ∼20% 34. The present study revealed that 13.3% of the cases presented with alopecia areata. Patchy alopecia areata was the most common pattern seen in 88.2% of the patients; this is similar to another study, which reported an incidence of 87.7% 35.
The dermoscopic finding of yellow dots in this study was seen in 91.25% of alopecia areata cases; this was close to another study that reported an incidence of 94.8% 36, whereas others 37 found the frequency to be 57.3%. The low incidence was attributed to the skin color of the patients, making the yellow dots difficult to perceive. These are sensitive markers for alopecia areata and correlate positively with disease severity 38.
The incidence of exclamation mark hairs in this study was 44.1% in alopecia areata cases, whereas it was 31.7 and 12.1% in other studies 37,38. This variance in percentage may be due to the different disease activity stages. These are specific for alopecia areata and indicate strong disease activity 38.
Black dots were seen in 58.8% of alopecia areata patients in this study; others demonstrated black dots in 67.7% of cases 35. Black dots represent pigmented hairs broken or destroyed at the scalp level 22. This sign is not seen in white population due to the hair color and cuticle resistance. This is a sensitive marker not only for disease activity but also for the severity of alopecia areata 38.
The presence of small vellus hair indicates the nondestructive nature of alopecia areata, allowing hair regrowth whether or not it results in completely mature hair shafts 38. In this study, vellus hair was present in 94.1% of the cases; other studies showed an incidence of 72.7% and 68% 37,38. The higher frequency is probably due to disease severity and inactive late-stage disease as explained by others 35,39.
Trichotillomania was found in 3.1% of the studied cases. An exact statistical number of individuals with trichotillomania in the general population is not available, and this is probably due to secretiveness of the disorder and under-recognition by medical professionals 40. A point prevalence of 4% has been estimated, with up to 10% of people having engaged in hair pulling at some point in their lives 41 and could be attributed to the socioeconomic problems that the family is passing through.
The onset of trichotillomania is prepubertal and there is a female predominance of 70–93% 42. This supports the present study, wherein the mean patient age was 9.5 years and 87.5% of the cases were female. Trichoscopy of the cases revealed hairs broken at different lengths, irregular coiled hairs, short hairs with trichoptilosis, black dots, amorphous hair residues, and microexclamation mark. These signs were similar to those reported by Rakowska et al.43, except that the new findings described as flame hairs, V-sign, hair powder, and tulip hairs were absent in the present study.
Although seborrheic dermatitis occurs most commonly in infants within the first 3 months of life 44, 6.7% of the patients in the present study had seborrheic dermatitis. On comparing these results with data from pediatric cross-sectional studies, it was found that the relative prevalence of seborrheic dermatitis in Greek outpatient children was 2.5%, 11.3% in Indian children, and 3.2% in Chinese children 45.
In this study, seborrheic dermatitis patients showed the diagnostic yellowish scales distributed in a diffuse pattern with the vascular features of dotted vessels in patchy distribution. Dermoscopy differentiates scalp psoriasis from seborrheic dermatitis by the specific vascular pattern of each disease 46.
In the present study secondary scarring alopecia was due to mechanical trauma, burn, previous shunt, and abscess. On trichoscopy, all patients showed loss of follicular ostia; this is similar to other studies, which agree that a variable degree of absence of follicular ostia is diagnostic and pathognomonic to the disease 26.
Scalp psoriasis in the present study showed a percentage of 1.2%, lower than that reported in South-East Nigeria (4.4%) 47. Psoriasis may be associated with psoriatic alopecia, which is noncicatricial and reversible 27. The white–silver scaling was found in 100% of the cases of the present study. The dermoscopic vascular features of scalp psoriasis of red dots and globules, twisted red loops, and glomerular vessels described by Rudnicka et al.27 were masked by the scales.
Despite pityriasis amiantacea being a distinct clinical entity, there were limited number of research studies on its etiology and associations. The underlying cause may be either psoriasis (most common), seborrheic dermatitis, atopic dermatitis, tinea capitis, or bacterial infections 48.
The characteristic dermoscopic finding for pityriasis amiantacea in this study was the presence of yellowish concretions that form thick, matted bundles holding the hairs together, similar to other studies 49.
The habitual use of chemical hair relaxers can result in hair loss 50. In this study, chemical burn due to hair relaxers was detected in the older group of 9–15 years of age. Dermoscopic examination of these patients only showed the remnants of the hair relaxers, although trichorrhexis nodosa may occur 27.
In this study, androgenetic alopecia cases were female and between 14 and 15 years of age. The diagnosis was confirmed with dermoscopy revealing hair diameter diversity in affected areas, with more than 20% of vellus hair, which is characteristic to this type of alopecia. These results are in agreement with other studies diagnosing androgenetic alopecia in children (aged 13.5–15 years) with the same dermoscopic findings and with female predominance 51,52.
Short anagen syndrome is a rare congenital disease characterized by persistently short fine hair since birth, due to decreased duration of the anagen phase 53. In the present study, trichoscopy was nonspecific and showed normal hair density with numerous upright regrowing hairs of different lengths, with pointed distal tip indicating that the hair was never cut or broken.
Ectodermal dysplasia is a rare disease (1 in 100 000 births) 54. Dermoscopic examination in this study revealed sparse hair. Most follicular units contain one hair; hair shafts bend in different directions at irregular intervals with diversity of pigmentation and pili torti. One of the patients showed diversity of hair shaft pigmentation and the other had albinism. All these dermoscopic findings were also documented by Rudnicka et al.27.
Folliculitis decalvans is a rare disease in children; two cases were detected during this study. The trichoscopic hallmark of multiple hairs emerging from one single dilated follicular orifice (polytrichia) was present with perifollicular erythema, crusting, and follicular pustules, similar to that reported in other studies 55.
Acne keloidalis is a chronic inflammatory process of the hair follicles of the nape, leading to fibrotic papules and plaques, occurring mostly in black male population after puberty 56. The case in this study was a 15-year-old White male. Dermoscopic examination revealed follicular hair tufts and perifollicular erythema, which is supported by Rudnicka et al.27.
In the present study, nevus sebaceous was seen in 0.4% of the cases; this is in agreement with the study that reported an incidence of 0.2% for nevus sebaceous in children 57. Our case showed yellow–orange plaque with warty appearance clinically and dermoscopically. The dermoscopic sign of bright yellow nonfollicular dots resembling the sebaceous glands 58 was not detected due to the age of the case (14 years), allowing the lesion to develop warty surface preventing the appearance of yellow dots.
In this study, although the overall number of patients is suitable, for some entities it was very small. This is particularly true for uncommon entities such as ectodermal dysplasia or folliculitis decalvans, which are represented with very few patients in the current study, and their dermoscopic pattern has not been extensively investigated by others before. We recommend studies with bigger numbers for these entities.
In conclusion, the routine use of dermoscopy in the clinical evaluation of scalp and hair disorders will improve the diagnostic capability beyond simple clinical inspection by revealing novel features of disease leading to better management.
Conflicts of interest
There are no conflicts of interest.
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Keywords:© 2017 Egyptian Women's Dermatologic Society
dermoscopy; hair loss; scalp disorders