[Invasive papillary and pseudopapillary (micropapillary) carcinoma of breast]

Classical invasive papillary carcinoma of the breast, is rare. In their pure form, they constitute 1.5% of all invasive breast carcinomas. Only one study clearly distinguishes them from intra-ductal papillary carcinomas; in this study they display a low metastatic potential and a relatively good prognosis. Lately, a new type of papillary carcinoma has been described which is characterized by inversion of the tumor cell polarity and papillations devoid of fibrovascular cores. Described by several authors by the term "micropapillary" carcinoma, the originally suggested term "pseudo-papillary" seems to be more appropriate; moreover, this designation would more clearly distinguish them from papillary carcinomas from which they clearly differ by their behavior. Furthermore, the pseudo-papillary carcinomas present an important lymphotropism, the effect of which on their clinical course is not yet clear. Further studies are necessary to determine whether these tumors, more frequent than classical papillary carcinomas, should be considered as a distinct clinical entity.