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Year : 2019  |  Volume : 20  |  Issue : 1  |  Page : 75-77

Congenital triangular alopecia: Clinical and dermoscopic differentials

Department of Dermatology, Venereology and Leprology, Rajiv Gandhi Medical College and Chhatrapati Shivaji Maharaj Hospital, Kalwa, Thane, Maharashtra, India

Date of Web Publication14-Dec-2018

Correspondence Address:
Dr. Vaibhav Kalambe
301, Yash Mauli CHS, Mahatma Phule Road, Near Bhoir Gymkhana, Dombivli West, Thane - 421 202, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijpd.IJPD_57_18

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Congenital triangular alopecia (CTA), also known as temporal triangular alopecia; originally described by Sabouraud in 1905; is a type of triangular, unilateral, nonprogressive, noncicatricial type of alopecia affecting mostly the temporal region of the scalp. It usually presents at birth or in early childhood, however adult cases have also been reported. Routinely confused with alopecia areata; dermoscopy helps in the diagnosis of this condition. We report a case of CTA with clinical and dermoscopic findings and discuss the differential diagnosis.

Keywords: Congenital temporal alopecia, dermoscopy, noncicatricial alopecia

How to cite this article:
Viswanath V, Kalambe V, Sanap D. Congenital triangular alopecia: Clinical and dermoscopic differentials. Indian J Paediatr Dermatol 2019;20:75-7

How to cite this URL:
Viswanath V, Kalambe V, Sanap D. Congenital triangular alopecia: Clinical and dermoscopic differentials. Indian J Paediatr Dermatol [serial online] 2019 [cited 2021 Nov 28];20:75-7. Available from: https://www.ijpd.in/text.asp?2019/20/1/75/247557

  Introduction Top

Congenital triangular alopecia (CTA), also known as temporal triangular alopecia (TTA) or Brauer nevus, is a type of circumscribed, nonprogressive, noncicatricial type of alopecia, which was originally described by Sabouraud in 1905 as “alopecia triangulaire congenitale de la temp.”[1]

We report a case of CTA manifesting since birth along with its clinical and dermoscopic differentials.

  Case Report Top

A 16-year-old male presented with a localized patch of hair loss over the frontotemporal region since birth. There was no history of any trauma during birth or any absence of skin. There was no history of consanguinity or any other family members affected by the same disorder. On clinical examination, triangular patch of alopecia measuring approximately 5 cm × 4 cm was present over the frontotemporal region of the scalp with base of the triangle in the front and apex toward the vertex [Figure 1].
Figure 1: Nonscarring, triangular-shaped area of alopecia. No signs of inflammation

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Dermoscopy (×50) showed vellus hairs in the bald patch along with normal terminal hairs surrounding the patch. The hair follicular openings were intact, and empty follicles were present [Figure 2] and [Figure 3].
Figure 2: Dermoscopy showing normal follicular openings and presence of vellus hairs covering the patch of alopecia

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Figure 3: Dermoscopy showing vellus hairs with terminal hairs at the periphery. Absence of black/yellow dots, or exclamation mark hairs

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Rest of the scalp hair, body hair, nails, and mucosae were normal. Systemic examination was normal. On histopathology, epidermis was normal. There was presence of vellus hairs along with miniaturization of hair follicles. There was absence of any inflammatory infiltrate [Figure 4]. Rest of the skin adnexa were normal. Prognosis was discussed with the parents of the patient and follicular unit extraction was suggested.
Figure 4: Number of hair follicles are in normal range, and epidermis and dermis are normal with the absence of any inflammatory infiltrate. The absence of streamers, unlike androgenetic alopecia (H and E, ×10)

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  Discussion Top

CTA; also known as TTA, is a type of circumscribed, nonprogressive, noninflammatory, noncicatricial type of alopecia. It remains stable throughout the life. It has an incidence of 0.11%.[2] There is no sex predominance. Even though the name states congenital, many of the cases manifest in pediatric age group, whereas in our case the symptoms were present since birth. There are also reports of the disease manifesting in adulthood.[3] It can present as triangular, oval, or lancet-shaped patch of alopecia.[4] Yin Li and Yesudian reported up to 79% cases presenting with unilateral involvement whereas the remaining showed bilateral involvement. Unilateral involvement was seen in our case.[5]

As the name suggests, temporal region of the scalp is the most common area affected; followed by frontotemporal and then the occipital in 2.5% cases.[6],[7]

Multiple pathomechanisms have been postulated to explain the nature of the disease; such as phylogenetic and embryological relation. Mosaicism is another proposed mechanism, and it is inherited as a para-dominant trait associated with postzygotic loss of the wild-type allele in a heterozygote state.[6] This can explain the pathogenesis in congenital variant of CTA; but not in acquired type. Acquired type of CTA arises from miniaturization of hair follicles; which ultimately forms the vellus hairs; characteristic of the disease.

Down's syndrome, iris-nevus syndrome, phakomatosis pigmentovascularis, aplasia cutis, congenital heart disease, and bone and tooth abnormalities may be associated with CTA.[8]

Differential diagnosis to be considered include alopecia areata, androgenetic alopecia (AGA), aplasia cutis, tinea capitis, and trichotillomania.

As alopecia areata remains the closest differential in this case, dermoscopy aids in the diagnosis of this rare entity and prevents the undue use of topical and intra lesional steroids. Dermoscopic features of CTA are intact follicular openings, empty follicles, presence of vellus hairs in the bald patch and presence of terminal hairs surrounding the patch.

Black dots, yellow dots, broken hairs, cadaverised hairs or exclamation mark hairs which are typical of alopecia areata are not seen in this disorder.[9]

Bilateral frontotemporal recession of the hairline differentiates CTA from AGA. Potassium hydroxide examination will help in differentiating between CTA and tinea capitis. Typical tonsure pattern of alopecia and perifollicular hemorrhage and pigmentation in dermoscopy, helps it to differentiate from trichotillomania.

No history of any trauma or absence of skin over the scalp since birth; rules out aplasia cutis. On histopathology, epidermis and dermis are unremarkable with no inflammatory infiltrate. There is normal number of follicles, presence of vellus hairs and miniaturization of the hair follicle. Rest of the skin adnexa such as sebaceous glands, sweat glands, collagen bundles, and vessels are normal.

Inui et al. have proposed a criteria to diagnose CTA.[9]

  1. Triangular or lancet-shaped patch of alopecia involving frontotemporal scalp
  2. Trichoscopically normal follicular openings with vellus hairs surrounded by normal terminal hair area
  3. Trichoscopically no broken hairs, tapering hairs, black dots, yellow dots and orifice loss, and
  4. Persistent without significant hair regrowth for 6 months after clinically or trichoscopically confirming the existence of vellus hairs.

There is no effective treatment modality for CTA, and the patient should be counseled regarding the benign nature of the disease. There are very few reports regarding use of topical minoxidil in the treatment of CTA.[10] Surgical excision is possible only in selected cases of small and localized patch of alopecia. Hair transplant can be an option for patients with psychological upset. This case was reported to diagnose such rare entity which can be easily mistaken for alopecia areata and undue use of topical and intralesional steroids can be avoided.

Informed consent

Taken from parents as our patient was a minor.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The Guardian understands that name and initial will not be published and due efforts will be made to conceal patient identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Sabouraud R. A Manual of Regional Topographical Dermatology. Paris: Masson; 1905. p. 197.  Back to cited text no. 1
Yamazaki M, Irisawa R, Tsuboi R. Temporal triangular alopecia and a review of 52 past cases. J Dermatol 2010;37:360-2.  Back to cited text no. 2
Trakimas CA, Sperling LC. Temporal triangular alopecia acquired in adulthood. J Am Acad Dermatol 1999;40:842-4.  Back to cited text no. 3
Verma P. Triangular temporal alopecia revisited. Indian J Dermatol 2016;61:125.  Back to cited text no. 4
[PUBMED]  [Full text]  
Yin Li VC, Yesudian PD. Congenital triangular alopecia. Int J Trichology 2015;7:48-53.  Back to cited text no. 5
Kudligi C, Bhagwat PV, Eshwarrao MS, Tandon N. Giant congenital triangular alopecia mimicking alopecia areata. Int J Trichology 2012;4:51-2.  Back to cited text no. 6
Taş B, Pilanci Ö, Başaran K. Congenital temporal triangular alopecia: A typical brauer nevus. Acta Dermatovenerol Alp Pannonica Adriat 2013;22:93-4.  Back to cited text no. 7
Unger R, Alsufyani MA. Bilateral temporal triangular alopecia associated with phakomatosis pigmentovascularis type IV successfully treated with follicular unit transplantation. Case Rep Dermatol Med 2011;2011:129541.  Back to cited text no. 8
Inui S, Nakajima T, Itami S. Temporal triangular alopecia: Trichoscopic diagnosis. J Dermatol 2012;39:572-4.  Back to cited text no. 9
Bang CY, Byun JW, Kang MJ, Yang BH, Song HJ, Shin J, et al. Successful treatment of temporal triangular alopecia with topical minoxidil. Ann Dermatol 2013;25:387-8.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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