Papillary carcinoma of the breast: imaging findings.

Papillary carcinoma is a rare malignant tumor of the breast for which the survival rate is better than for most breast carcinomas. Histologically, invasive and in situ forms occur; the in situ form can extend throughout a ductal system (intraductal) or can be confined within a cystic structure (intracystic). Invasive papillary carcinoma can spread from either of the in situ forms but spreads more commonly from the intracystic type. Many reports in the literature have failed to differentiate invasive from in situ papillary carcinomas; similarly, the different mammographic patterns of the two in situ forms of these lesions have not been delineated clearly. Our review of 16 new cases of papillary carcinoma showed a frequent correlation between the histologic types and the mammographic appearance. The intraductal in situ form usually was characterized by clustered microcalcifications. The intracystic in situ type was associated with well-circumscribed masses on mammograms; these masses often were complex on sonograms. The purpose of this essay is to illustrate the mammographic and sonographic features of the histologic varieties of papillary carcinoma. Color Doppler sonograms and MR images of intracystic and invasive tumors also are included.