Fibrocystic change of the breast presenting as a focal lesion mimicking breast cancer in MR imaging.

Focal fibrocystic change (FCC) of the breast is a rare form of FCC. Imaging presentations of focal FCC are not well known. This study aimed to analyze its MR imaging features. Eleven patients of pathology-proven focal FCC were retrospectively studied. Of the 11 patients, seven were mass (>or=5 mm), two showed multiple foci, and two were focus (<5 mm). The lesion size ranged from 4-12 mm (mean 6.7 mm). Morphologically, three patients were suspected as malignancy. Using kinetic enhancement curve, 8 of 13 lesions were suspected to be malignant. Overall, nine patients (82%) were suspected for malignancy using either criterion. Using mammography, 6 of the 11 patients (55%) were diagnosed as malignancy. Breast sonography suspected malignancy in seven patients (7/10, 70%). No statistically significant difference was found in the three diagnostic methods. In pathology, all 11 patients showed the typical pathological features of fibrocystic change, with mixed components of stromal fibrosis, cyst formation, apocrine metaplasia, adenosis, and/or focal sclerosing adenosis. In conclusion, MR imaging features of focal FCC usually present as a mass or focus lesion with rapid enhancement and washout kinetics that mimic a malignant breast lesion and lead to unnecessary operation, especially in patients with contralateral malignant breast cancer.