The affected area is probably present from birth, but because hair growth can be sparse in newborns it can be some months or even years before it becomes significantly noticeable. The affected area is often roughly triangular shaped but may be oval in some individuals. The affected skin contains mostly vellus hair follicles. The cause of congenital triangular alopecia is not known, but its presence is not usually associated with any adverse disease state.
Affected individuals are typically entirely healthy.
The hair loss is non-progressive and does not expand beyond these areas. The condition is permanent and the affected skin does not change later in life. There is no treatment other than to graft hair follicles to the affected area. Clinical and histologic findings in temporal triangular alopecia. J Am Acad Dermatol.