INVASIVE MICROPAPILLARY CARCINOMA OF THE BREAST

Nine examples of a rare variant of invasive breast carcinoma character ized by the formation of micropapillae within clear spaces separated b y a fibrocollagenous or delicate fibrovascular stroma are presented. D esignated as invasive micropapillary carcinoma, the unusual morphology of this tumor requires its distinction from metastatic ovarian serous papillary carcinoma and extensive vascular/lymphatic invasion by eith er a primary or metastatic breast carcinoma. The micropapillary patter n is retained in metastatic foci and areas of recurrence. This pattern also occurs admired with regular infiltrating duct carcinoma either i n the primary mammary tumor or when it recurs.