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Special Feature
December 1998

Pathological Case of the Month

Author Affiliations

Copyright 1998 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.1998

Arch Pediatr Adolesc Med. 1998;152(12):1242. doi:
Diagnosis and Discussion: Temporal Triangular Alopecia and Aplasia Cutis Congenita

Figure 1. A view of 2 congenital alopecic scalp lesions in a 9-year-old African American boy.

Figure 2. A 10 × 10-mm circular atrophic scar of aplasia cutis congenita, located on the posterior vertex of the scalp and completely devoid of hair. This is the typical location for this congenital lesion.

Figure 3. A 45 × 17-mm, lancet-shaped patch of temporal triangular alopecia on the left temporal area of the scalp. Fine, vellus hairs cover the lesion.

Figure 4. Photomicrographic view of a vertical section of aplasia cutis congenita showing extensive dermal fibrosis and absence of adrenal structures (hematoxylin-eosin, original magnification ×20).

Figure 5. Photomicrographic view of a transverse section of temporal triangular alopecia. Left, Level of reticular dermis showing miniaturized vellus hairs (hematoxylin-eosin, original magnification ×40). Right, Level of subcutaneous fat readily demonstrating absence of terminal hair structures (hematoxylin-eosin, original magnification ×40).

Aplasia cutis congenita is a relatively common, congenital, localized absence of skin, usually occurring on the scalp. Although clinical presentation may vary at birth, mature lesions of aplasia cutis congenita are atrophic scars devoid of adnexal structures.1 Most commonly, aplasia cutis congenita is an isolated finding that is not associated with other abnormalities.

Temporal triangular alopecia (TTA) is a stable form of nonscarring alopecia, usually diagnosed between the ages of 2 and 6 years.2 In congenital TTA, the lesions are present at birth.3 It is characterized by an oval- or lancet-shaped alopecic patch located unilaterally or bilaterally in the temporofrontal area, with the pointed tip of the lesion directed superiorly and posteriorly. Although infrequently reported, TTA is believed to be relatively common. There seems to be no sexual preference for the condition, but it has not yet, to our knowledge, been reported in African Americans.2 We also know of no reports of TTA associated with other scalp disorders.4

Histopathologically, TTA is characterized by an absence of inflammation and a normal number of hairs that are all miniaturized.2,4 The abnormal histologic condition of this lesion is best evaluated by transverse section, where the number and type of hairs can be quantified. The normal number of scalp hairs on a 4-mm punch biopsy specimen transverse section is 20 to 40 hairs, with a terminal-vellus ratio of 2:1 to 4:1.4,5

To the best of our knowledge, this case represents the first incidence of TTA in an African American, and the first report of the simultaneous occurrence of aplasis cutis congenita and TTA.

Accepted for publication July 14, 1998.

The views expressed herein are those of the authors and do not necessarily reflect the views of the US Army or the US Department of Defense.

Corresponding author: Julie R. Kenner, MD, PhD, Dermatology Service, Department of Medicine, Tripler Army Medical Center, 1 Jarrett White Rd, Honolulu, HI 96859-5000.

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Trakimas  CSperling  LCSkelton  HGSmith  KJBuker  JL Clinical and histologic findings in temporal triangular alopecia.  J Am Acad Dermatol. 1994;31205- 209Google ScholarCrossref
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Sperling  LC Hair anatomy for the clinician.  J Am Acad Dermatol. 1991;251- 17Google ScholarCrossref