[231] Histologic Characteristics of Benign Breast Lesions Identified for Biopsy by Magnetic Resonance Imaging

MM Johnson, V Dialani, NB Johnson. Massachusetts General Hospital, Boston, MA; Beth Israel Deaconess Medical Center, Boston, MA

Background: Contrast-enhanced magnetic resonance imaging (MRI) of the breast is being used more frequently as a screening modality for high-risk patients. Although quite sensitive, it suffers from poor specificity. In this study we sought to evaluate histologic features of breast biopsies diagnosed as benign that may correlate with the abnormal signal enhancement seen on MRI studies.
Design: The cases records of the Beth Israel Deaconess Medical Center were searched for biopsies of benign breast lesions identified as displaying abnormal or suspicious features (Breast Imaging and Reporting Systems (BIRADS) 4a, 4b or 4c) by MRI. The H&E stained slides were reviewed and evaluated for the following features: diagnostic lesion, prominent vascularity (intra- and extralesional), large-caliber vessels, proportion of fatty to nonfatty tissue, and epithelial versus stromal predominance in nonfatty tissue. Additional clinical features were also examined.
Results: Thirty-seven cases of benign breast lesions categorized as abnormal or suspicious by MRI were identified. Forty-nine percent were categorized as BIRADS 4a, 38% as BIRADS 4b and 13% as BIRADS 4c. Five cases (13%) showed specific diagnostic features of mass-forming lesions, including four fibroadenomas and one papilloma. The remaining cases showed benign breast tissue with or without fibrocystic change. Most cases (92%) displayed stromal-predominant rather than epithelial-predominant nonadipose tissue. Forty-nine percent of biopsies consisted predominantly of fatty tissue. One (3%) of 31 cases with lesional tissue showed prominent intralesional vascularity and two (5%) of the 37 cases showed prominent extralesional vascularity. Twelve (32%) cases showed large caliber vessels, all but one case identified within adipose tissue.
Conclusions: Increased vascularity, the expected histologic correlate for MRI enhancement, was only identified as a prominent feature in a small minority of the studied benign cases. Large-caliber vessels were identified within adipose tissue in 33% of cases; however, it is unclear whether this correlates with specific signal enhancement by MRI. Most cases showed non-specific features of benign breast tissue, predominantly stromal changes, without impressive histologic differences from normal breast tissue. Perhaps technical factors (i.e. fat suppression, sampling) rather than inherent vascular changes may be responsible for signal enhancement in these cases.
Category: Breast

Monday, March 22, 2010 1:00 PM

Poster Session II # 29, Monday Afternoon


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