Curious bald spot on a young girl's head

THE CASE    

The mother of a 7-year-old girl brings her to the office for evaluation of eczema. On review of symptoms, she mentions concern about a bald spot above her daughter’s right ear, noticeable when she braids her hair. The bald spot has been stable; it does not itch; and it is not painful for the child. The mother denies trauma or hair pulling. She is concerned that this might continue to spread and her child might become completely bald. 

NEXT: What's the diagnosis?

DERMCASE diagnosis: Temporal triangular alopecia

First described in 1905,¹ triangular temporal alopecia (TTA) is a nonprogressive type of hair loss confined to the frontotemporal scalp that can be triangular, lancet, or oval shaped.² In the triangular cases, the apex is often aligned toward the vertex of the head.³ It can be unilateral or bilateral, and it affects boys and girls almost equally as well as multiple ethnic groups including cases reported among Caucasian, Asian, and African American populations.²

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Etiology

Originally described as congenital, TTA also may be acquired later in life, although most cases occur between birth and 9 years of life.⁴ The exact cause is unknown, and it can be associated with disorders such as Down syndrome, Turner syndrome, LEOPARD syndrome, phakomatosis pigmentovascularis, Pai syndrome, or Klippel-Trenaunay syndrome in up to 15% of cases.² Histologically, TTA is a replacement of hair follicles by sparse, vellus hair with miniaturized follicles.

Differential diagnosis

The differential diagnosis should include tinea capitis, alopecia areata, traction alopecia, androgenetic alopecia, aplasia cutis, sebaceous nevus, or trichotillomania.² Trichoscopy with a polarized light can be helpful in determining the diagnosis although it is often purely clinical with visualization of vellus hairs with varying length diversity. The diagnosis can help parents and providers avoid further invasive studies or ineffective treatment. The hair pull test should be negative.

Treatment

Treatment is not necessary in most cases because TTA is a nonprogressive and permanent condition. Reassurance is the most important guidance a physician can provide for families concerned about further hair loss. Corticosteroids have not been shown to result in hair regrowth.

One case study found that treatment with topical minoxidil improved the condition but did not show long-term effects after cessation of treatment.⁴ In cases where cosmetic concerns are significant, hair restoration surgery is an option.

The patient

On physical exam, the patient was noted to have a 2-cm alopecic patch on the right temporal area with the apex pointing toward the vertex (Figure). After reassurance about the benign nature of the process, the patient was discharged home with a plan for follow-up and no treatment at this time.

REFERENCES

1. Sabouraud R. A Manual of Regional Topographical Dermatology. Paris: Masson; 1905:197.

2. Yin Li VC, Yesudian PD. Congenital triangular alopecia. Int J Trichology. 2015;7(2):48-53.

3. Gupta LK, Khare A, Garg A, Mittal A. Congenital triangular alopecia: a close mimicker of alopecia areata. Int J Trichology. 2011;3(1):40-41.

4. Bang CY, Byun JW, Kang MJ, et al. Successful treatment of temporal triangular alopecia with topical minoxidil. Ann Dermatol. 2013;25(3):387-388.

Dr Rossi is a third-year pediatric resident at Johns Hopkins Children’s Center in Baltimore, Maryland. She attended medical school at Jefferson Medical College in Philadelphia, Pennsylvania. Dr Cohen, section editor for Dermcase, is professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore. The author and section editor have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article. Vignettes are based on real cases that have been modified to allow the author and section editor to focus on key teaching points. Images also may be edited or substituted for teaching purposes.