Encapsulated Papillary Carcinoma of the Breast

Papillary lesions of the breast include a broad spectrum of entities, many of which can be diagnostically challenging for the pathologist. This article focuses on encapsulated papillary carcinoma, a recently proposed term used to describe papillary carcinoma occurring within a cystically dilated duct. Previously considered a variant of papillary ductal carcinoma in situ, the finding that these lesions typically lack myoepithelial cells at their periphery has raised questions about their true nature. This article presents a practical approach to the diagnosis of encapsulated papillary carcinoma with a review of its histologic mimics and clinical significance.