Congenital Triangular Alopecia (CTA) - 13 % of the Time, it's not the temples!

Atypical Locations for Congenital Triangular Alopecia.

Congenital Triangular Alopecia (CTA) is a type of localized hair loss that typically affects the temples. The condition develops in early childhood but may not be present immediately at birth. The key to the diagnosis is the finding of a patch of hair loss in the temples. The shape of the area of hair loss is usually triangular in nature and the pointy aspect of the triangle points upwards to the crown. Trichosocpy shows vellus hairs with no broken hairs or black dots to suggest alopecia areata. The area does not regrow.

Typical Position of Congenital Triangular Alopecia

Inui’s Original 2012 Criteria for Diagnosing Congenital Triangular Alopecia

1. Triangular or spread shaped area of hair loss in temples

2. Trichoscopic features of normal follicular openings with vellus hairs

3. No yellow, black dots or dystrophic hair and no loss of ostia

4. No hair growth

Starace et al, 2020

Starace and colleagues recently published an interesting report of 78 patients with CTA. 68 of the patients (87%) had the typical temple location as the site of the location. However, 10 fo 78 patients (13 %) had an atypical location for the hair loss including occipital area (5 patients), parietal area (4 patients) and vertex (1 patient).

Atypical Occipital location of congenital triangular alopecia (CTA). Approximately 6 % of individuals with congenital triangular alopecia may have an atypical occipital form. SOURCE: Starace M et al. Atypical Presentation of Congenital Triangular Alopecia: A Case Series in Italy. Dermatol Pract Concept Oct 2020. used with creative commons license.

Conclusion and Comments

This is an interesting paper. We are programmed to think of CTA as occurring only in the temples. This paper reminds us that in up to 13 % of cases that type of thinking is not going to be useful as CTA can occur in other areas.

REFERENCES

Starace M et al. Atypical Presentation of Congenital Triangular Alopecia: A Case Series in Italy. Dermatol Pract Concept Oct 2020

Inui S, Nakajima T, Itami S. Temporal triangular alopecia: trichoscopic diagnosis. J Dermatol. 2012;39(6):572–574.