BACKGROUND Atrophic dermatofibrosarcoma is a rare clinical variant of dermatofibrosarcoma protuberans (or Darier-Ferrand tumor) preferentially observed in childhood and early adulthood. OBSERVATION We report a case of multifocal atrophic dermatofibrosarcoma protuberans of childhood onset only diagnosed when the patient was 29 years old. The clinical presentation was an asymptomatic macular brown plaque on the right thigh measuring 10 cm. Initially, because of the large size of the lesion, treatment consisted of limited surgical excision. DISCUSSION Diagnosis of the atrophic variant of dermatofibrosarcoma in childhood is difficult, and is usually made several years later in early adulthood because of its slow development, lack of symptoms and generally benign appearance. Histological tests and immunohistochemical staining may confirm clinically suspected diagnosis, and in complex cases, cytogenetic studies can help confirm a diagnosis of dermatofibrosarcoma through detection of reciprocal translocation t (17,22), which fuses collagen type Ialpha1 (COLIA1) and platelet-derived growth factor (PDGDFbeta), and which is highly characteristic of dermatofibrosarcoma protuberans. Conventional treatment of dermatofibrosarcoma protuberans consists of extensive surgical excision, but Mohs micrographic surgery is also advocated for removal of certain dermatofibrosarcoma protuberans, while use of tyrosine kinase PDGF receptor inhibitors such as imatinib mesylate (Glivec) is limited to distant metastases.