Abstract
We present a case of fibromatosis of the breast that is rare. The case involved a 34-year-old woman presented with a dimple on the skin of the right breast. When she first presented to our hospital, a 15-mm sized scirrhous tumor with dimpling was palpated in the B area of the right breast and a mammography revealed a localized asymmetric shadow in the right L area. Ultrasonography revealed a 14×17×14 mm irregular shaped tumor. The tumor was suspected to be malignant because it was associated with interruption of the anterior border of the mammary gland and posterior echo attenuation. Breast MRI scan, however, showed a pattern suggestive of benign. Fine needle aspiration biopsy cytology revealed bundle like proliferation of spindle-shaped cells, which lacked in cellular atypia, in the background of plenty of collagen fiber, and the nuclei were positive for β-catenin. Fibromatosis of the breast was thus diagnosed. We performed partial resection of the breast by keeping a surgical margin with the width of 1.5 cm and confirmed the surgical stump to be negative. There have been no signs of recurrence as of 3 months after the surgery. Local recurrence rate of fibromatosis of the breast is high so that further careful observation of her clinical course would be mandatory.
