Nodular fasciitis of the breast

We report a case of nodular fasciitis of the breast, which is a rare histological type of breast tumor. A 41-year-old woman had noticed a mass in her right breast. The mass was elastic-hard, 15 mm x 15 mm in size, and located mainly in the upper outer quadrant of the right breast. Mammography demonstrated an oval dense mass with spiculation. Ultrasonography revealed a hypoechoic lesion, 8 mm x 10 mm in size. Fine needle aspiration cytology and core needle biopsy showed no evidence of malignancy. Excisional biopsy was performed. The tumor was characterized by a proliferation of fibroblastic cells. Histologically, the excised tumor was consistent with nodular fasciitis of the breast. Nodular fasciitis should be considered in the differential diagnosis of a mass suspicious for breast cancer.