[Papillary lesions of the breast]

Papillary lesions of the breast encompass a spectrum of both benign and malignant lesions despite sharing a similar basic architecture. A reliable distinction between the different entities is possible even in biopsies with precise knowledge of the diagnostic criteria and using immunohistochemistry as a diagnostic adjunct. These include papilloma, papillary ductal carcinoma in situ, encapsulated papillary carcinoma and solid papillary carcinoma. Architectural features, cellular composition and distribution of myoepithelial cells as highlighted by immunohistochemistry are the major diagnostic criteria. In this review the most useful morphological and immunohistochemical criteria for routine diagnostic practice are presented.