An Unusual Case of Congenital Triangular Alopecia on Frontal Area Successfully Treated by Surgery.

Congenital triangular alopecia (CTA) is a form of circumscribed, noncicatricial, and noninflammatory hair loss. It manifests as a triangular or oval-shaped alopecic patch on the frontotemporal region of the scalp and rarely involves the temporoparietal or occipital area. That is why it is also called temporal triangular alopecia. However, there has been just one case reported in the middle frontal area. Here, we report a successfully treated case of CTA in a 17-year-old boy who was born with a 2.5 cm × 3.5 cm alopecic patch in the middle frontal area. Copyright:

INTRODUCTION

Congenital triangular alopecia (CTA), also known as temporal triangular alopecia or brauer nevus, was first reported in 1905 by Sabouraud.[1] CTA is a circumscribed, noncicatricial, noninflammatory hair loss disease.[2] It manifests as a triangular or oval alopecic patch.[3] CTA is usually noted in children between 3 and 9 years of age and is sometimes associated with diseases such as Down syndrome, leukonychia, sectorial hyperpigmentation of the iris, woolly hair, mental retardation, and other malformations. CTA is usually confined to the frontotemporal region and is rarely seen in middle frontal or occipital area.[2] Here, we report a case of CTA arising from the frontal region and successfully treated with serial excision.

CASE REPORT

A 17-year-old male presented with an asymptomatic wedge-shaped alopecic patch on the right frontal area [Figure 1a]. He had an alopecic patch since birth, and there was no change in size. No specific defect or fetal scalp problem had been observed during the delivery. He denied a history of trauma or traction at the site of the alopecia. Dermatological examination observed a well-defined, 2.5 cm × 3.5 cm triangular patch without skin changes such as erythema and atrophy [Figure 1b]. There were no other changes in hair or nail involvement.

Figure 1

(a) A 17-year-old male with an alopecic patch on his frontal area. (b) A 2.5 cm × 3.5 cm well-circumscribed triangular alopecic patch with vellus hair. No atrophy, erythema, or inflammation was observed

Trichoscopy revealed vellus hair with white hair and white dots [Figure 2a]. Skin biopsy from the patch revealed miniaturized hair follicles. There was mild perifollicular infiltration of inflammatory cells [Figure 2b and c]. He was diagnosed with CTA. Medical treatments such as topical corticosteroids and 5% minoxidil were tried first but did not show improvement, which confirmed the diagnosis. Thereafter, serial excision was performed, which resulted in a better outcome [Figure 3].

Figure 2

(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, ×40)

Figure 3

(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

DISCUSSION

CTA is a part of the group of nonscarring alopecia first described by Sabouraud in 1905.[1],[2],[4] It appears at birth or during the first 9 years of life and remains stable thereafter.[2] It is a rare skin disease, and its incidence has been estimated at 0.11%.[5] Its etiology is unknown. However, it is presumed that the local hair follicles are miniaturized due to factors such as mosaicism and ectodermal defects, resulting in vellus hair. Some genetic associations have been implicated based on the relation between CTA and some genetic disorders and syndromes such as phakomatosis pigmentovascularis.[6]

It typically manifests as an area of triangular, oval or lancet-shaped alopecia localized over the frontotemporal scalp.[5] It does not respond to medication such as topical corticosteroids.[7] In a previous study of 53 cases, 55.8% occurred on the left side, 30.8% on the right side, and 13.5% in bilateral lesions of the temporal or frontotemporal area. It may also be located in the temporoparietal and occipital regions.[1],[4] In our case, the patient had several CTA characteristics such as a wedge-shaped patch since birth and noneffective treatment except for in the frontotemporal location. Among 170 previously reported cases, there has been only 1 case in the middle frontal area.[6]

Histopathology and trichoscopy are helpful in the diagnosis of CTA as well as for differential diagnosis with alopecia areata and androgenetic alopecia. Histopathological findings often reveal vellus hairs and rare terminal hairs on the superficial dermis.[5] The total number of follicles may be normal, but follicles tend to be smaller.[2] There are no changes in the epidermis or dermis. White hairs with a range of diameters are the most frequent features observed in trichoscopic findings.[8] Vellus hair follicles surrounded by terminal hairs may replace terminal hair follicles in affected areas.[8],[6] Other trichoscopic features include empty follicles, white dots, and an arboriform vascular pattern.[8]

Surgical treatments such as excision or hair transplantation are the treatment of choice in CTA and show good cosmetic outcomes. Medical treatment is usually not effective, although there have been some cases that show a good response with minoxidil 5%.[9]

Our case is a rare case of CTA presenting on the frontal area treated by surgery. CTA may be considered a potential diagnosis to avoid unnecessary investigations and treatments.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.