Focal fibrosis of the breast: imaging characteristics and histopathologic correlation

To characterize mammographic and ultrasonographic (US) features of focal fibrosis of the breast (FFB), to compare the radiologic and histopathologic findings, to investigate the incidence of FFB, and to determine if histopathologic diagnosis of FFB is an acceptable diagnosis for specific mammographic and US findings.

Retrospective review of findings from 1,268 surgical excisional and 796 percutaneous breast biopsies (290 US-guided, 370 stereotactically guided, and 136 vacuum-assisted stereotactically-guided) revealed 44 (2.1%) diagnoses of FFB. Mammographic and US features were correlated with histopathologic types.

Thirty-seven (84%) of the 44 lesions diagnosed as FFB were visualized on mammograms and appeared as six (14%) circumscribed masses, two (5%) lobulated masses, one (2%) microlobulated mass, 11 (25%) obscured masses, two (5%) architectural distortions, and 15 (34%) asymmetric densities. Seven palpable lesions were not visualized on mammograms. Thirty-three of the 44 lesions were evaluated at US; 25 (76%) of 33 were visible. Twenty (80%) of 25 were well-defined hypoechoic masses; three (12%), ill-defined masses; and two (8%), marked shadowing without visible mass. At histopathologic examination, 17 (39%) of the 44 lesions were characterized as mass-like fibrosis; 14 (32%), as nodular fibrosis; 12 (27%), as haphazard fibrosis; and one (2%), as septal fibrosis. Histopathologic type and specific imaging findings did not correlate statistically.

FFB is a histopathologic entity that has a wide spectrum of imaging findings. It is an acceptable histopathologic result of percutaneous breast biopsy, provided that careful radiologic-histopathologic clinical correlation is performed.