[160] Histopathology of MRI-Guided Breast Core Biopsies.

Lindsay Goicochea, Cristina Campassi, Meredith Watts, Olga Ioffe. University of Maryland Medical Center, Baltimore

Background: Breast MRI has been increasingly used for screening women at high risk for breast cancer and as part of the work-up of newly diagnosed breast carcinoma. Before the advent of MRI-guided core biopsies, histologic correlates of abnormal MRI findings have been difficult to identify in surgical resection specimens. Examination of the MRI-directed core biopsies allows for a more precise radiologic-histologic correlation; however, this has not yet been addressed by pathology literature.
Design: 56 consecutive MRI-guided 9 and 10 gauge vacuum-assisted breast core biopsies in 48 women (31-76 years) were retrospectively reviewed. Lesions which had mammographic or sonographic correlates were excluded from review. The indications for MRI study were high-risk screening in 27, and work-up of newly diagnosed cancer in 21 patients.
Results: Malignancy was found in 3 of 31 (9.7%) biopsies performed for high-risk screening, and 3 of 25 (12%) additional tumors were found during work-up of new breast cancers (NS); all of the latter carcinomas were ipsilateral while two thirds were contralateral in women with previous diagnosis of breast cancer. The only significant MRI features predictive of malignancy were plateau kinetics (40% of cancers vs 7% benign lesions) and MRI size of the lesion –19.8 vs 12.3 mm, p<.05. Plateau kinetics were also seen in 2 sclerosing/papillary lesions and one fat necrosis. Benign histologic findings which were considered histologic correlates of MRI abnormalities were: proliferative breast disease in 18 including intraductal papilloma/sclerosing lesion in 9; inflammation (lymphocytic mastopathy and duct ectasia) in 10; trauma/iatrogenic cause in 7; fibroadenomatoid nodules and pseudoangiomatous stromal hyperplasia (PASH) in 7; and 2 mucocele-like lesions. The target was thought to have been missed in 7 cases, in one of which excision revealed invasive carcinoma. Overall, surgical excision was carried out in 17 cases and resulted in upgrade to malignancy in all atypical lesions and all mucocele-like lesions but none of the benign processes listed above.
Conclusions: MRI-guided breast core biopsies offer an opportunity to find precise morphologic correlates for MRI-detected abnormalities. We have found that proliferative and inflammatory lesions are the most common causes of benign MRI enhancement. Excision should be recommended for all non-concordant histologic results, as well as for atypical and mucocele-like lesions.
Category: Breast

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 27, Tuesday Morning


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