Invasive micropapillary carcinoma. Distinct features of a poorly recognized variant of breast carcinoma

Introduction. Invasive micropapillary carcinoma (IMC) is a histological var iant of breast cancer with a poor prognosis. Material and Methods. Pathological findings of 15 cases of IMC are compared with those of 144 invasive duct carcinoma (IDC) and 10 invasive papillary carcinoma (IPC). Results: Only 33% of cases were diagnosed in stage 1. Mean tumor size was 2 .3 cm. Nuclear grade 3 was found in 60% of cases, aneuploidy in 78%. and 92 % had hormone receptors. Nine patients showed lymph node metastasis. Tumor size, nuclear grade, mitotic rate and lymph node involvement were higher in IMC when compared with IDC grade I and IPC, but not when compared with IDC grade II and III. Four cases of IMC (27%) recurred before two years. Recur rences and lymph node metastases showed the same architectural pattern as t he primary tumor. Discussion. IMC shows a high incidence of lymph node involvement and ii hig h early recurrence rate.