PMC7276158_01
(a) A 17-year-old male with an alopecic patch on his frontal area. (b) A 2.5 cm x 3.5 cm well-circumscribed triangular alopecic patch with vellus hair. No atrophy, erythema, or inflammation was observed
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F1
A 17-year-old male presented with an asymptomatic wedge-shaped alopecic patch on the right frontal area [Figure 1a]. Dermatological examination observed a well-defined, 2.5 cm x 3.5 cm triangular patch without skin changes such as erythema and atrophy [Figure 1b].
(a) Trichoscopy of congenital triangular alopecia with vellus hair, showing white hair with a range of diameters. (b) Vertical section of a biopsy specimen showing normal epidermis, dermis, and adnexa (H and E, 40). (c) Horizontal section of a biopsy specimen showing the number of hair follicles. The hair follicles were smaller than normal. There were telogen hairs and vellus hairs. Mild inflammation was observed around the follicles (H and E, x40)
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F2
Trichoscopy revealed vellus hair with white hair and white dots [Figure 2a]. There was mild perifollicular infiltration of inflammatory cells [Figure 2b and c].
(a) After the first surgery, the lesion was slightly smaller than before. (b) After the second surgery, there was no other abnormality except erythema of the incision line
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F3
Thereafter, serial excision was performed, which resulted in a better outcome [Figure 3].