Pathologic Findings of Breast Lesions Detected on Magnetic Resonance Imaging.

CONTEXT: - Breast magnetic resonance imaging (MRI) is now used routinely for high-risk screening and in the evaluation of the extent of disease in newly diagnosed breast cancer patients. Morphologic characteristics and the kinetic pattern largely determine how suspicious a breast lesion is on MRI. Because of its high sensitivity, MRI identifies a large number of suspicious lesions. However, the low to moderate specificity and the additional cost have raised questions regarding its frequent use. OBJECTIVES: - To identify the pathologic entities that frequently present as suspicious enhancing lesions and to identify specific MRI characteristics that may be predictive of malignancy. DESIGN: - One hundred seventy-seven MRI-guided biopsies from 152 patients were included in the study. The indication for MRI, MRI features, pathologic findings, and patient demographics were recorded. The MRI findings and the pathology slides were reviewed by a dedicated breast radiologist and breast pathologists. RESULTS: - Seventy-one percent (126 of 177) of MRI-guided breast biopsies were benign, 11% (20 of 177) showed epithelial atypia, and 18% (31 of 177) showed malignancy. The vast majority (84%; 62 of 74) of MRI lesions with persistent kinetics were benign. However, 57% (17 of 30) of lesions with washout kinetics and 65% (62 of 95) of mass lesions were also benign. CONCLUSIONS: - Magnetic resonance imaging detects malignancies undetected by other imaging modalities but also detects a wide variety of benign lesions. Benign and malignant lesions identified by MRI share similar morphologic and kinetic features, necessitating biopsy for histologic confirmation.

Features of non-mass enhancing lesions detected on 1.5 T breast MRI: a radiologic and pathologic analysis.

BACKGROUND: With increased utilization of magnetic resonance imaging (MRI) of the breast in clinical practice, many non-mass lesions are being detected incidentally. Although MRI-guided biopsies are usually performed for these lesions, no clear guidelines exist to determine the management of these lesions. OBJECTIVE: The purpose of this study was to explore the pathological features of incidentally detected non-mass lesions on breast MRI to determine rates of malignancy and to assess the predictive value of kinetic enhancement curves for further characterization of these lesions as benign versus malignant. METHODS: A retrospective review was performed of all MRI-guided core needle biopsies done at our institution between January 2009 and January 2012. RESULTS: 172 consecutively biopsied lesions were identified. 43% of the lesions were non-mass lesions, out of which 74.3% were benign, whereas 14.9% and 10.8% of these lesions had malignant and atypical features, respectively. The most commonly encountered non-mass malignant lesion was ductal carcinoma in situ, whereas the most frequently seen invasive non-mass lesion was invasive lobular carcinoma. Kinetic enhancement curves for these lesions did not demonstrate a statistically significant relationship with their pathologic features. CONCLUSIONS: Non-mass enhancing lesions incidentally detected on breast MRI carry a significant risk of atypia and malignancy, either in situ or invasive. Hence, it is prudent to biopsy these lesions.