Abstract: 【Abstract】 Objective To summarize the clinical, pathological, and molecular genetic features of dermatofibrosarcoma protuberans （DFSP） in children. Methods A retrospective analysis was conducted on clinical data from 8 children with DFSP in the Department of Dermatology, Beijing Children′s Hospital, Capital Medical University from January 2017 to December 2024. General information, clinical manifestations, pathological examinations, molecular genetic examinations, and treatments were analyzed, and clinical features and prognosis were summarized. Results All the 8 cases were females, with ages at onset （M［Q1, Q3］） of 1.3 （0.3, 2.6） years, including 2 congenital cases; their ages at diagnosis were 5.1 （3.7, 7.4） years. Skin lesions manifested as solitary dark red patches, plaques, or nodules, and were located on the trunk in 5 cases （3 on the back, 1 on the abdomen, and 1 on the chest） and on the lower limbs in 3 cases. Histopathological examinations of all the 8 cases showed tumor cells diffusely infiltrating the dermis and subcutaneous tissue without epidermal involvement. Immunohistochemical staining showed that all the cases were strongly positive for CD34 and negative for soluble 100 protein; the Ki-67 labeling index （M［Q1, Q3］） was 9.0% （8.0%, 17.5%）. Fluorescence in situ hybridization revealed the COL1A1-PDGFB fusion gene or PDGFB gene rearrangement in all 8 cases. All the patients underwent surgical excision of the primary skin lesions, including 3 treated with wide local excision, 2 with traditional Mohs surgery, and 3 with modified slow Mohs surgery, and all achieved negative margins. During the follow up of 6 months to 7 years, no tumor recurrence was observed. Conclusions DFSP often occurred at a relatively young age in children, and mostly presented as atrophic patches or plaques. PDGFB gene alterations were commonly observed, and prognosis after surgical treatment was generally favorable.

Key words: Dermatofibrosarcoma, Dermatofibrosarcoma protuberans, Child, Immunohistochemistry, In situ hybridization, fluorescence