A solitary triangular alopecia

An otherwise well, five‐year‐old girl was brought in by parents for review of a bald patch over the left frontotemporal scalp which was noticed from the age of two years. Clinically, the bald area was a solitary smooth and shiny patch of alopecia with apex pointing posteriorly (Figure, A), consistent with a congenital triangular alopecia (CTA), also known as temporal triangular alopecia. The diagnosis was supported by the dermoscopic features of CTA:1,2 i) normal follicular openings with vellus hairs centrally (Figure, B; blue) and terminal hairs (Figure, B; red) at the periphery the lesion; ii) absence of “exclamation mark” hairs; and iii) absence of black and yellow dots (Figure, B) — presence of the features described in the second and third points could indicate alopecia areata and other entities. CTA is a localised non‐scarring and non‐progressive alopecia that occurs on either side of the frontotemporal scalp, with triangular, spear or oval shape.2 It usually remains unchanged throughout the life.1,2 CTA may mimic with alopecia areata, traction alopecia, trichotillomania, and congenital aplasia cutis.1,2 No effective treatment has been reported for CTA, and surgical excision, if the area is small, or hair transplant may be considered.1,2