A Case of Basal Cell Carcinoma Arising in Congenital Triangular Alopecia.

Congenital triangular alopecia (CTA) is a rare, non-scarring form of hair loss that typically presents in childhood. We present the case of a 48-year-old woman with CTA who developed basal cell carcinoma (BCC) within the right temporal alopecic patch, representing, to our knowledge, the first documented instance of malignant transformation to BCC in this condition. This case highlights the importance of evaluating long-standing alopecic areas for potential malignancy. Although the mechanisms linking CTA to carcinogenesis are not fully understood, factors such as alterations in the local immune microenvironment, increased ultraviolet exposure, and genetic predispositions may play a role in this rare transformation.