Review of Breast Cancers That Can Mimic a Cystic Component: Ultrasonographic and Pathologic Correlations

differentiation of a cyst from a solid lesion (1, 2). Cystic breast lesions may be associated with numerous pathological entities, but malignant cystic breast masses are rare. Mixed cystic and solid carcinomas of the breast are uncommon findings and constitute 0.3% to 2.0% of all breast carcinomas (2, 3). There are three situations in which a cystic lesion can be associated with malignancy described as an invasion of a carcinoma into an area of cystic disease, cystic degeneration of a high-grade malignancy, and the presence of an intracystic papillary carcinoma (3). Berg et al. (2) described the sonographic and pathologic correlations of cystic lesions of the breast in which 23% (18/79) of the complex cystic masses were found to be malignant. It is suggested that 67% (12/18) of sonographically circumscribed cystic masses were malignant and that sonography may be helpful in identifying those circumscribed masses that merit a biopsy. A malignant cystic mass of the breast can be seen with a circumscribed margin on imaging. Circumscribed cancers of the breast are listed as infiltrating ductal carcinomas not otherwise specified (IDC-NOS), mucinous carcinomas, medullary carcinomas, papillary carcinomas, phyllodes tumors and adenoid cystic carcinomas (4). Imaging findings of various malignant cystic breast masses with pathological correlations are illustrated. Knowledge of the disease spectrum, as well as the characteristics of malignant cystic masses, may be helpful in the selection of whether to perform a biopsy as part of patient management. J Korean Soc Radiol 2011;64:273-279