Abstract: BACKGROUND ＆ AIM: To investigate the pathological features, immunochistochemistry and prognosis of carcinoma with micropapillary pattern (MPP) in different extramammary sites. MATERIALS AND METHODS: 33 cases with MPP were evaluated for pathologic features and examined for the immunohistochemical expression of EMA, E_cadherin (E_cd), CD44v6 and Ki67. Follow_up was undertaken. RESULTS: 33 cases of carcinoma with MPP occurred in different anatomic sites, including lung, urinary bladder, kidney and large intestine. Microscopically, the tumor was characterized by small papillae of malignant cells floating within irregular interstitial spaces.There were lymphatic invasion in all cases and nodular metastases in 25 cases. The foci of expression of EMA, E_cd, CD44v6 were different from those of ordinary carcinoma in the same sites. Follow up showed 23 cases died and 3 cases recurred or metastasized in short time. CONCLUSION: Extramammary carcinoma with MPP occur at various anatomic sites, including lung, urinary bladder, pancreas and large intestine. These tumors share a high propensity for lymphatic invasion and lymph node metastases. Presence of this histological pattern should alert clinicians for more active treatment and closer follow up.

Key words: carcinoma, micropapillary pattern, immunohistochemistry, prognosis