Complex cystic breast masses: diagnostic approach and imaging-pathologic correlation.

Complex cystic breast masses demonstrate both anechoic (cystic) and echogenic (solid) components at ultrasonography (US). US is used to identify and characterize such masses and to guide percutaneous biopsy. Numerous pathologic entities may produce complex cystic breast lesions or may be associated with them, and biopsy is usually indicated. Common benign findings include fibrocystic changes, intraductal or intracystic papilloma without atypia, and fibroadenoma. Common atypical findings include atypical ductal hyperplasia, atypical papilloma, atypical lobular hyperplasia, and lobular carcinoma in situ. Malignant findings include ductal carcinoma in situ, infiltrating ductal carcinoma, and infiltrating lobular carcinoma. If the biopsy approach is tailored to the individual patient and if the imaging features are closely correlated with findings at pathologic analysis, US-guided percutaneous biopsy may be used effectively to diagnose and to guide management of complex cystic masses.