Abstract: 【Abstract】 Objective To investigate clinical features of congenital triangular alopecia. Methods Clinical data were collected from 10 children with congenital triangular alopecia, who were diagnosed and treated in Xiamen Children′s Hospital from August 2020 to June 2021, and their clinical and dermoscopic features were analyzed. Results All the 10 patients were males, aged from 2 months to 6 years and 4 months. Hair loss occurred at birth or within 1 month after birth in 6 children, and occurred between the age of 4 months and 6 years in 4. The alopecic area was located in the left frontotemporal region in 5 patients, in the right frontotemporal region in 3, and in the vertex region in 2. In all the patients, thin vellus hairs could be seen in the alopecic areas, the hair pull test was negative, but some normal terminal hairs were scattered in the alopecic area in 1 patient. Dermoscopy showed a large number of vellus hair surrounded by normal terminal hairs in the alopecic area with a clear boundary, and no yellow or black dots, or 'exclamation mark' hairs were observed. Seven patients had visited department of dermatology due to hair loss, of whom 5 were diagnosed with alopecia areata, and 2 with sebaceous nevus. Conclusions Congenital triangular alopecia is common in children, and mostly occurs in the left frontotemporal region. It is characterized by the replacement of normal terminal hairs by thin vellus hairs in the alopecic area. Dermoscopy is helpful in its diagnosis and differential diagnosis.

Key words: Alopecia, Child, Dermoscopy, Congenital triangular alopecia