CTA is a noncicatricial, non-inflammatory form of localized alopecia, That most commonly affects an area on the frontotemporal suture in the shape of an oval, triangular or spear-like alopecia And is usually unilateral, although some bilateral cases have been reported.
The presented case is an example of an alopecia presented at birth, although the term congenital is a misnomer since most reported cases arise between the ages of 2 to 9 years and many reported cases were acquired in adulthood.
Upon dermoscopic examination, sparse velus hair follicles replace terminal hair follicles in the affected area; Although, there have been cases where a few normal terminal hairs were seen within the alopecic patch. Even a tuft of terminal hair or multiple islands of normal hair growth have been reported. Vellus hairs are short, and vary in length; but the number of the hair follicle units are kept within the normal range. also white hairs may be seen.
CTA has been associated with a number of different disorders in about 15% of cases. This disorders include: bone abnormalities, café-au-lait patches, Congenital dislocation of the hip, Congenital heart diseases, dandy-walker malformation, dysesthesia within hairless areas, epilepsy, hydronephrosis, hypospadias, iris nevus, leukonychia, mental retardation, multiple lentigines, recurrent bronchiolitis, spina bifida, teeth abnormalities, tracheoesophageal fistula, woolly hair nevus, wormian bones.
CAT may convey an autosomal dominant inheritance when it presents in association with a syndrome; such as Down’s, LEOPARD, Pai syndromes, Phakomatosis pigmento vascularis. The etiology of CTA is not clear, but some genetic links have been implicated based on the association between CTA and some genetic disorders and syndromes such as phakomatosis pigmentovascularis which would point to a loss of heterozygosity as an underlying cause for CTA and it could postulate a predominant inheritance order. Mosaicism has also been suggested to be the underlying cause for CTA. Others have proposed that CTA may be an ectodermal defect that should be classified under the group of epidermal nevi.
Overall, the exact etiology of this disorder remains unknown; and contrary to many many theories base on familial inheritance that have been presented, CTA usually emerges sporadically; as in the case that we hereby present; but there are no implications that this disorder can be explained by a phylogenic or embryological theory.
In 2012 Inui et. al. suggested a diagnostic criteria consisting of four of the major clinical components of CTA. (1) A frontotemporal patch of hair-loss with a triangular or spear-like shape; (2) Vellus hairs with normal hair follicles surrounded by terminal hair: (3) absence of fractured or exclamation mark hairs and no black or yellow dots with a preserved follicular orifice; and (4) lack of significant hair growth 6 months after confirming the presence of vellus hairs on dermoscopy.
We believe that the incidence of CTA is generally underestimated, which can be due to the benign and non-progressive nature of the disease or the fact that a majority of affected patients are misdiagnosed with other types of noncicatriciel alopecia, as shown by Garcia-Hernandez et. Al. where an evaluation of 6200 patients with alopecia resulted in 7 confirmed diagnosis of CTA.