Dermatofibrosarcoma protuberans (DFSP) is an extremely rare sarcoma with an incidence between 0.8-5.0 cases per one million persons per year. DFSP accounts for less than 0.1% of all malignancies and approximately 1-6% of all soft tissue sarcomas. Only a few cases of DFSP have been found within the breast tissue. We report a case of DFSP in a 30-year-old female within the left breast. The sarcoma presented as a painless, rubbery, mobile lump that gradually increased in size. It was initially identified on an ultrasound scan and subsequently confirmed with MRI and core biopsy.

DFSP is a rare condition and treatment guidelines are not well established. The current recommendation is for surgical excision with 2-cm margins. Mastectomy may be considered in some circumstances. In our case, the aim was for surgical resection with 2-cm margins at both breast tissue and skin, but insufficient margins were taken. The recommendation for re-excision of the inadequate margins was declined. It is uncertain what the implications of this are given the lack of research on DFSP in the breast. Therefore, close surgical surveillance will be imperative. We present this case to highlight the difficulties associated with the diagnosis, treatment, and management of DFSP due to the lack of literature on this disease.