Dermatofibrosarcoma protuberans is a rare form of soft tissue sarcoma that tends to invade and recur locally. The most common site of this disease is head, neck and extremities; however, the involvement of the breast has been reported. We present a case with a dermatofibrosarcoma of the breast that is composed of low-grade spindle cells which are positive for CD43. She was treated by wide surgical excision followed by adjuvant external beam irradiation at a dose of 60 Gray. After a follow-up of 24 months, no local-regional or distant recurrence was detected.