Case for diagnosis

Abstract

A 6 year-old patient began to experience localized hairloss in the right temporal region three years ago. During the first appointment, diagnoses of alopecia areata and congenital triangular alopecia were made. After one year, there was no change. Upon dermatological examination, non-scarring alopecia was noted in the right temporal region, revealing extremely fine and fair hair follicles. A dermoscopy revealed only thin vellus-type hairs. Congenital triangular alopecia is a condition commonly confused with alopecia areata and is thus underdiagnosed. However, well-established clinical parameters and dermoscopic criteria can be used to distinguish skin diseases that affect hair and define the diagnosis.

Congenital triangular alopecia

“…[ 14 42 ] However, hair follicles are miniaturized[ 35 45 46 ] with an increased proportion of vellus or indeterminate hairs. [ 14 18 45 50 ] This may be due to abnormalities in follicle morphogenesis and supports the idea that CTA is a form of a hamartomatous mosaic disease possibly involving an abnormal, local, epithelial-mesenchymal interaction. [ 35 ] Collagen bundles and vessels in the dermis shows no abnormalities; sweat glands and sebaceous glands are normal in size and number.…”

“…Congenital triangular alopecia is likely underreported and in reality, not an uncommon disorder. It may be underdiagnosed due to diagnostic confusion with other types of nonscarring alopecia[ 50 ] and under reported due to its asymptomatic and nonprogressive nature. [ 42 ] Future advances in molecular and genetic studies will help to reveal the exact etiology this condition.…”

“…This condition was first described in 1905 by Raymond Sabouraud in his book “ Manuel élémentaire de dermatologie topographique réégionale ” as “ alopecia triangulare congenitale de la temp .”[ 1 ] As of January 2015, 126 cases have been reported worldwide, as shown in Table 1 . [ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 ] It typically affects the frontotemporal region [Figures 1 and 2 ], although there have been reported cases of CTA affecting the temporoparietal[ 15 42 46 ] and occipital scalp. [ 36 37 ] It is a nonprogressive disorder, which presents as a triangular, oval or lancet-shaped patch of alopecia.…”

“…Congenital triangular alopecia is associated with other disorders in up to 15% of cases[ 50 ] and may occur as a key feature in a multiple malformation syndrome. [ 28 ] Common associated features are listed in Table 3 and syndromes in Table 4 .…”