Temporal triangular alopecia and a review of 52 past cases

Temporal triangular alopecia (TTA) is a circumscribed, non‐cicatricial form of alopecia confined to the frontotemporal region. The patient, a 15‐year‐old boy, was noticed at birth to have an alopecial area, sized 1.5 cm × 2.5 cm, in the right temporal region. Microscopic examination revealed miniaturized hair follicles accompanied by differentiated sebaceous glands. We have provided a synopsis of the past 52 cases. Of the 53 cases of TTA including our case, more than half (55.8%) were detected in childhood between the ages of 2 and 9 years, while 36.5% were detected at birth and only 3.8% (only two cases) in adulthood. There were three familial cases. Several congenital diseases were associated with the condition, for example, phakomatosis pigmentovascularis, Down syndrome and Dandy–Walker malformation. This information suggests that TTA can be recognized as a hamartomatous mosaic disease.