MRI features of stromal fibrosis of the breast with histopathologic correlation.

OBJECTIVE: The purpose of this article is to present the MRI features of stromal fibrosis of the breast, thus enabling radiologists to better determine radiologic-pathologic concordance of biopsy results and appropriate patient management.

MATERIALS AND METHODS: A retrospective review of radiology records between 2003 and 2009 identified 123 MRI-detected lesions with the histologic diagnosis of stromal fibrosis. Of these, 83 cases were excluded either because stromal fibrosis was not the primary histologic diagnosis, or because there were associated pathologic abnormalities that may have contributed to contrast enhancement. The remaining 40 lesions with a primary histologic diagnosis of stromal fibrosis were included in our study. Their MRI and histopathologic features were examined and categorized.

RESULTS: The lesions included five foci, 23 masses, and 12 areas of nonmasslike enhancements. The prevalent features of the masses were size smaller than 1 cm (20/23 [87%]), round or oval shape (16/23 [70%]), irregular or spiculated margins (15/23 [65%]), rapid or medium rate of initial contrast uptake (21/23 [91%]), and plateau or washout curves (16/23 [70%]). Most nonmass lesions showed clumped enhancement (9/12) and linear distribution (7/12). Many of these features were suggestive of malignancy. Twenty-seven of 40 cases (68%) had histologic confirmation by excision or MRI confirmation of benignancy. No false-negative cases have been identified to date. Histopathologic correlation showed the presence of masslike septal fibrosis associated with ectatic vascular channels in 60-67% of cases, which may lead to increased contrast enhancement on MRI.

CONCLUSION: Stromal fibrosis has widely variable MRI features, often mimicking breast carcinoma. It may represent an acceptable benign concordant diagnosis on vacuum-assisted large-core needle biopsy for the described MRI findings.