Fibromatosis of the breast in a male patient

Fibromatosis of the breast is a rare soft tissue lesion that arises from the mammary tissue or the pectoral fascia. We present a case of fibromatosis in a 39-year-old male patient who developed a right lateral breast mass in several weeks without prior trauma or surgery. Ultrasound-guided core needle biopsy findings included differential diagnoses of nodular fasciitis and fibromatosis. The patient was referred to a breast surgeon and underwent excisional biopsy. Final pathology report confirmed fibromatosis. The patient tolerated the surgery well and will continue to follow up post-operatively for recurrence.