Significance Of Incidentally Detected Oval, Circumscribed Enhancing Lesions On Preoperative Breast Mri.

12 Background: To evaluate the characteristics and malignancy rate of oval, circumscribed enhancing lesions seen on preoperative breast MRI in patients with breast cancer.From January 2010 through May 2013, a total number of 502 oval, circumscribed mass was incidentally found in 326 patients with breast cancer who had undergone preoperative breast MRI. Seventy-eight lesions were excluded due to the lack of follow-up imaging or total mastectomy. Biopsy was performed when suspicious enhancing kinetics or interval change were detected on MRI. Otherwise, MRI or ultrasound follow up for correlated lesion were performed at least 2 years. Clinical and imaging features were recorded for analysis.Of the 424 oval, circumscribed enhancing lesions detected on MRI, twelve (2.8%) were malignant and 412 (97.2%) were benign. There was no significant difference in size between malignant (0.72±0.26 cm) and benign (0.71±0.34 cm) lesions (p = 0.932). Among 424 lesions, 43 lesions (10.1%) were pathologically confirmed and twelve were malignant. Positive predictive value (PPV) of malignancy for the biopsy was 27.9%. Among 12 malignant lesions, 7 (58.3%) were invasive ductal carcinoma, 4 (33.3%) were ductal carcinoma in situ, and 1 (8.3%) was tubular carcinoma. Of the pathologically confirmed benign lesions, 8 (25.8%) were fibroadenoma, 7 (22.6%) were intraductal papilloma. Interestingly, there were significantly frequent MRI features with early fast enhancement and delayed washout pattern in malignant (11/12) compared to benign (29/412) lesions (p < 0.001). PPV of malignancy for early fast enhancement and delayed washout pattern in MRI was 27.5%.Cancer yield in patients with oval, circumscribed enhancing lesion on preoperative breast MRI was 12 (2.8%) of 424. MRI features with early fast enhancement and delayed washout pattern strongly suggested malignancy.