Micropapillary variant of transitional cell carcinoma of the ureter.

Micropapillary variant of transitional cell carcinoma (TCC) is a rare entity, having a distinct micropapillary component mimicking papillary serous carcinoma of the ovary and has been reported exclusively in the urinary bladder. We experienced a case of micropapillary variant of TCC in the ureter. The tumor showed a predominant proportion of micropapillary component and accompanied a TCC in situ lesion and a high-grade TCC. A metastatic lesion in the regional lymph node also showed an entirely micropapillary pattern. Initially, our case was confused with adenocarcinoma, especially metastatic, because the micropapillary architecture resembled an abortive glandular structure and tumor cell nests were predominantly located in empty spaces mimicking vascular invasion. The patient died with peritoneal metastases 20 months after the initial diagnosis. We report the first case of a micropapillary variant of TCC occurring in the ureter.