Aims: Invasive micropapillary carcinoma (IMPC) is a special variant of breast carcinoma. The aim of this study was to investigate the relationship between clinicopathologic features of IMPC, lymph node metastasis and patients’ outcome to verify if this subtype of breast carcinoma is associated with a poor prognosis.
Methods: All cases of invasive carcinoma were reviewed in a 10-year period and 61 pure IMPC cases were identified. Clinical, histopathologic and immunohistochemical features, treatment type and outcome were evaluated. Chi-square test and Student’s t-test were used for statistical analyses. Results were considered to be significant at p < 0.05.
Results: All patients but 1 were women. Tumor size ranged from 0.3–10 cm. In 60 cases, 20 (33%) were grade 3. Of 49 patients with lymphatic permeation, 37 (76%) had lymphovascular invasion. Multifocality occurred in 21 (34%) cases and metastatic axillary nodes in 38 (62%). In 55 (90%) cases there was positivity for estrogen receptors and in 48 (79%) for progesterone receptors; HER2 was overexpressed in 21 (35%). Over a median follow-up of 61 months, six (10%) patients suffered disease progression. Disease-specific mortality rate was 5%.
Conclusion: We found that lymph node metastasis was correlated with tumor size, high histologic grade, lymphovascular invasion, multifocality and HER2 positivity. Axillary lymph node metastasis and the burden of axillary node involvement were predicting factors related with poor prognosis. In this series, the cases with positivity for estrogen and progesterone receptors were associated with a more favorable outcome.