Desmoid fibromatosis of the breast occurring after breast reduction surgery mimicking a carcinoma: A rare case report.

Introduction: Desmoid tumors are benign mesenchymal tumors developed at the expense of muscular fasciae and aponeuroses. The mammary localization is a rare entity, representing less than 0.2% of all breast tumors. It is characterized by a strictly local evolution and its tendency to recur without giving metastases. Its clinical and radiological presentation is similar to a breast carcinoma which is the main differential diagnosis.

Case presentation: Patient aged 51 years, primigravida primiparous, followed for right breast cancer diagnosed at the age of 49 years for which she received a right mastectomy and axillary lymphnode dissection and contralateral breast reduction. It was a 4 cm infiltrating ductal carcinoma, SBR III Luminal B, 0 N+/20 N with presence of fibrous mastopathy without sign of malignancy at the left breast reduction specimen.The patient received adjuvant chemotherapy, external radiotherapy and hormone therapy.One year after surgery, the patient returned for a four x 2 cm left breast nodule in the upper medial quadrant. The biopsy confirmed the diagnosis of fibromatosis of the breast. A wide local excision was performed.

Discussion: The etiology of this tumor is unknown, however, physical, hormonal and genetic factors play an important role in the development of desmoid tumor.The clinical presentation is similar to breast carcinoma, making it difficult to differentiate this tumor from breast carcinoma. Breast imaging techniques are not specific for desmoid fibromatosis. Treatment is based primarily on complete surgical excision.

Conclusion: Breast fibromatosis is a rare entity, clinically and radiologically mimicking breast cancer. Only histology will provide the diagnosis. The treatment of choice is based on complete surgical excision with healthy safety margins.