Trichoscopy of Focal Alopecia in Children
Hair Clinic in Concord says that the majority of alopecia in children is presented as patchy alopecia, which is most commonly diagnosed as alopecia areata. However, other causes of patchy alopecia such as tinea capitis, trichotillomania, temporal triangular alopecia (TTA), nevus sebaceous, and aplasia cutis congenital (ACC) can be easily missed.
Trichoscopy (hair and scalp dermoscopy) is a rapid in-office technique, which has become a standard procedure in the differential diagnosis of hair loss. The process can easily confirm alopecia areata due to its particular trichoscopy features: exclamation mark hairs, yellow and black dots, and credibility hairs. The microscopic features of trichotillomania in adult patients (flame hairs, tulip hairs, coiled hairs, hook hairs, v-sign, and irregularly broken hairs) have been described. In contrast, the characteristic findings in tinea capitis (comma hairs, zigzag hairs, corkscrew hairs, and block hairs) have also been documented. We know that there is only one description referring to the trichoscopy of ACC. Microscopic findings in TTA have been described as normal follicular openings with vellus hairs covering the area of alopecia and terminal hairs on the outskirts of the lesion.
The study established the usefulness of trichoscopy in the differential diagnosis of the abovementioned entities.
Procedures of Trichoscopy
The study was a retrospective analysis (2012–2015) and included 68 patients under 6 years of age (39 girls and 29 boys; median age 4.5 years; range 14 months to 6 years) and was approved by the local committee. The inclusion criteria were age and the presence of 1–3 alopecia patches. A total of 124 alopecia patches were examined using a video dermoscopy as a routine procedure, of which 102 were recognized as alopecia areata, 8 as tinea capitis, 6 as trichotillomania, 3 as TTA, and 5 as ACC. Other procedures to confirm the diagnosis included bronchograms, fungal cultures, and histopathological examinations. In 1 patient, ACC was recognized as a spectrum of Kabuki syndrome. This diagnosis was based on typical facial abnormalities, short stature, and mild mental retardation. Three small patches of alopecia were also present. The 2 remaining patients had a sporadic type without other abnormalities. In all cases, the patches of alopecia were present from birth (in utero healing).
At the edge of patchy alopecia, radially arranged hair bulbs are visible. These hair bulbs are directed into the middle of the lesion, with dark pigmented proximal ends (typical for the anagen phase). There are no follicular openings at the center of the lesion, but a vascular network resembling a spider’s web is seen.
Two independent blinded evaluators analyzed a total of 453 images (abnormalities in hair shaft structure and skin surface were to be described). The results were unblinded, and the evaluated microscopic features were assigned to the appropriate patient group.
The occurrence of the scored trichoscopy criteria within each group (alopecia areata, trichotillomania, tinea capitis, and TTA) was evaluated by respective Z tests. To prevent alpha inflation in repeated tests, the significance level was adjusted according to Bonferroni (α = 0.05/n) and set-top < 0.001
Results
Identified trichoscopy abnormalities in the evaluated patient groups included broken hairs, coiled hairs, upright regrowing hairs, exclamation mark hairs, tapered hairs, flame hairs, tulip hairs, v-sign, hook hairs, black dots, yellow dots, regrowing pigtail hairs (circular or oval), hypopigmented vellus hairs, comma hairs, corkscrew hairs, zigzag hairs, upright regrowing hairs and radially arranged hair bulbs at the border of alopecia lesions.
Trichoscopy revealed hair bulbs visible through the semitranslucent epidermis in all ACC lesions. All were elongated, with very dark proximal ends (typical for anagen bulbs observed under the microscope). All bulbs were seen at the hair-bearing margin and were arranged radially. The central parts of the lesions showed no follicular openings. However, prominent vasculature was observed, corresponding to skin atrophy in these areas. This finding was highly specific for ACC and was not found in other diseases.
According to a hair clinic in Walnut Creek, broken hairs as a feature of trichotillomania were found in 100% of cases. However, they were also observed in 5% of alopecia areata and 87% of tinea capitis lesions. Coiled hairs were observed in 33% of trichotillomania and 12.5% tinea capitis lesions. There were no cases of helical strands found in other groups. Flame hairs (wavy and cone-shaped hair residues) were specific for trichotillomania (67%). Other characteristic features of trichotillomania included v-sign (33%) and tulip hairs (50%). V-sign (2%) and tulip hairs (2%) were also found in alopecia areata patches.
Specific features of trichotillomania can be seen: irregularly broken hairs, coiled hairs, v-sign, and circle hairs.
Yellow dots (37%), black dots (42%), and exclamation mark hairs (36%) were all prevalent in alopecia areata lesions. Micro-exclamation mark hairs were also found in trichotillomania lesions (17%) but were not present in tinea capitis, triangular alopecia, and ACC. Tapered hairs were found only in alopecia areata patches (10%). Hair regrowth was observed in the majority of alopecia areata patches in children — upright regrowing hairs (44%), circular hairs (23%), and vellus hairs (20%).
Tinea capitis lesions showed specific trichoscopy features — comma hairs (50%), corkscrew hairs (12.5%), and zigzag hairs (50%). As mentioned above, broken hairs (87%), coiled hairs (12.5%), and regrowing pigtail hairs (12.5%) were also observed but were not specific for this diagnosis.
In cases of TTA, upright regrowing hairs and regrowing pigtail hairs were observed inside the patch and surrounded by terminal hairs on the outskirts of the lesions.
Conclusion
Trichoscopy is a useful technique for the differential diagnosis of patchy alopecia in children, hair clinic in east bay area say that. A novel finding in this study indicates that radially arranged hair bulbs visible through the translucent epidermis are characteristic of nonbullous type ACC. This knowledge can help clinicians perform a quick and painless diagnosis of ACC in newborns. In such cases, ocular and neurological anomalies should be investigated. In alopecia areata, regrowing hairs (vellus hairs, upright regrowing hairs, and circle hairs) appear more prevalent in children than in adults. TTA lacks specific trichoscopy features, but the presence of short hairs (vellus hairs, upright regrowing hairs, and coiled strands) on the patch are sufficient to establish a proper diagnosis.
