Primary mucinous adenocarcinoma of the renal pelvis with carcinoma in situ in the ureter

Primary epithelial tumor of the renal pelvis is rare and only 100 cases are reported in the literature [1]. Histological examination of the tumor showed glands, cysts, and papillae lined by pseudostratified columnar epithelium with hyperchromatic nuclei. Scattered signet ring-type cells were also seen floating in large pools of extracellular mucin. Sections from the ureter showed a component of adenocarcinoma in situ. No invasive tumor was identified in ureteric tissue. One case was reported with carcinoma in situ of the ureter (2).Immunohistochemically: The tumor showed positivity for CK7, CK20, CK8/18, GATA-3, MSH-2, MSH-6, MLH-1, Ber-EP4, and S-100-P with focal positivity for CDX-2, weak positivity for PMS-2 and negativity in TTF-1 and Her-2. Molecular pathological analysis revealed microsatellite stability and without mutation in K-ras-gene. Thus, a diagnosis of mucinous adenocarcinoma of the renal pelvis with in situ adenocarcinoma of the ureter was made.