2.1. Study population

After Institutional Review Board approval, we searched the Asan Medical Center database for patients with facial scars who visited the outpatient clinic of the department of dermatology between January 1990 and June 2021. Cases with complete medical records, including sex, age, onset and cause of facial scars, presence of symptoms, and medical photographs of the lesions at the initial visit were included. Patients who had received scar treatment (except for wound dressing) before their visit, those with scars resulting from injury within 1 month, and patients with wounds displaying incomplete healing were excluded. All cases with missing photographs were also excluded. Furthermore, given that keloid scars have distinct pathogenesis compared to other types of scars, patients diagnosed with keloid were excluded from the study.