Breast fibromatosis: Imaging and clinical findings.

Breast fibromatosis is a rare histologically benign tumor with local aggressive potential, and imaging and clinical findings of breast fibromatosis require attention. We retrospectively evaluated the images of 20 patients with histologically proven breast fibromatosis on mammography, magnetic resonance imaging (MRI), and ultrasonography. The lesions were assessed concerning the location, fascia involvement, imaging characteristics, and follow-up outcomes. Altogether, there were 22 lesions: 10 lesions involved the superficial fascia system including four lesions additionally involving the deep fascia and pectoralis major, and 12 lesions were inside the glandular parenchyma with two lesions originated from the prior surgery site. The detection rates of mammography, ultrasound, and MRI for breast fibromatosis were 33.3% (3/9), 90% (18/20), and 100% (3/3), respectively. We found that fascia involvement may be a characteristic of breast fibromatosis. The lesion located inside glandular parenchyma is prone to be underestimated, whereas combined MR with ultrasound is recommended for the diagnosis. The complete excision with negative margins is important for a good prognosis.