[262] MRI-Guided Breast Core Biopsies: Pathologic Features of Newly Diagnosed Malignancies

Emily S Reisenbichler, Susan C Lester. Brigham and Women's Hospital, Boston, MA

Background: Magnetic resonance imaging (MRI) of the breast is used for select groups of patients. The likelihood of detecting malignancy is related to the reason for the examination. This study reviewed a large series of MRI-guided breast core needle biopsies to determine the incidence and types of cancers found and to correlate the cancers with the MRI findings and the indication for the study.
Design: MRI-guided breast core biopsies, performed at our institution over 1 year, were identified with review of corresponding clinical, diagnostic radiology, and pathology reports. Patients were categorized according to MRI indication: high risk (family history, germline mutation, prior chest radiation, or contralateral breast cancer), evaluation of disease extent in patients with current cancer, surveillance for recurrence of prior cancer, and as a problem solving method. Lesion characteristics by MRI and final pathologic diagnoses were recorded.
Results: One hundred-thirty-six consecutive core biopsies were performed on 120 patients. Most patients (n=75, 63%) underwent MRI due to a high risk of breast cancer. Within this screening group, the most common risk indicator was family history without a germline mutation. Malignancies (atypical ductal hyperplasia (ADH) with ductal carcinoma in situ (DCIS) upgrade at excision, DCIS, or invasive carcinoma) were identified in 29 (22%) of the biopsies. Analysis of the types of MRI lesions did not identify any lesions with a likelihood of malignancy over 50%. All cases of DCIS presented as non-mass-like enhancement (NMLE). Invasive carcinomas presented as both mass forming lesions (58%) and NMLE (42%). The highest malignancy rate (5 of 8 biopsies, 62.5%) was in the group with prior ipsilateral breast cancer. The lowest malignancy rate was in the group undergoing screening (15 of 86 biopsies, 17%). Of the 9 invasive carcinomas identified by screening, 8 (89%) were small (< 1 cm) and all showed a favorable prognostic receptor profile (estrogen receptor (ER) positive, HER2 negative). Of the 6 cases of DCIS identified in the high risk group, all demonstrated intermediate or high nuclear grade with ER negativity in 3 (50%) of cases.
Conclusions: MRI-guided core biopsies demonstrated a rate of malignancy (in this high risk population) similar to that seen for mammographic lesions in the general population. The type of MRI lesion did not correlate well with the likelihood of malignancy or the type of malignancy. The most common types of carcinomas identified by screening were small ER positive invasive tumors and high grade ER negative DCIS.
Category: Breast

Monday, March 4, 2013 1:45 PM

Proffered Papers: Section B, Monday Afternoon


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