Background. There have been 12 documented cases of choriocarcinoma arising in the urinary bladder, either alone or in combination with other epithelial tumors. It has been shown that some high-grade transitional cell carcinomas (TCC), without obvious syncytiotrophoblastic elements, can produce human chorionic gonadotropins (HCG).Methods. A case of choriocarcinoma, in association with high-grade TCC of the renal pelvis, was encountered in an 80-year-old man. For additional evaluation of HCG production by TCC, 25 consecutive cases of invasive high-grade TCC of the bladder were stained with an anti-HCG antibody. Immunogold staining also was performed in two of the cases studied.Results. Immunoperoxidase staining of the renal pelvis tumor showed focal positivity for HCG within the TCC and a more intense reaction as the tumor cells differentiated into choriocarcinoma elements. Seven of the 25 cases (28%) displayed varying degrees of reactivity within individual cells or groups of cells. In an additional case, typical syncytiotrophoblastic giant cells without cytotrophoblasts were seen in a high-grade TCC. Immunogold studies demonstrated positive labeling in the cytoplasm of carcinoma cells in a case of TCC without syncytiotrophoblasts and in the syncytiotrophoblastic giant cells in the one case in which these were present.Conclusions. The findings support a metaplastic origin of cases of choriocarcinoma arising primarily in the urothelial tract.

Malignant spindle cell neoplasms are a diagnostic challenge regardless of their location. In the retroperitoneum a major consideration in the differential diagnosis is sarcomatoid renal cell carcinoma; if an epithelial component cannot be recognized histologically, special studies may be required to reach the correct diagnosis. In an attempt to better characterize this entity, 23 cases of sarcomatoid renal cell carcinoma (6.3%) were identified from a review of 363 renal cell carcinomas. Blocks were available for immunohistochemical analysis in 18 cases. The epithelial and sarcomatoid portions were studied with a panel of antibodies directed against cytokeratin (AE1/AE3, CAM 5.2, and 34 beta E12), epithelial membrane antigen, Leu-M1, muscle-specific actin, S100 protein, desmin, and vimentin. The epithelial nature of the spindle cell component was best demonstrated by positive reactivity with the anti-cytokeratin AE1/AE3 (in 17 [94%] of the 18 cases). The other epithelial markers stained the spindle cell component less frequently: cytokeratin CAM 5.2 in seven cases (39%); epithelial membrane antigen in nine cases (50%); and high-molecular-weight cytokeratin 34 beta E12 in no cases (0%). In 10 cases (56%) vimentin positivity and in six cases (33%) actin positivity was seen in the spindled areas. The spindle cell component stained for Leu-M1 in four cases (22%) and for S100 protein in one case (6%) and did not react for desmin in any case. From this study we conclude that in the majority of sarcomatoid renal cell carcinomas the epithelial nature of the spindle cells, as indicated by cytokeratin expression, can be documented using immunohistochemical methods.

We have used modern techniques of direct microscopic examination and quantitative bacterial recovery to show the existence of a route of bacterial colonization along the external and internal surfaces of Tenckhoff catheters implanted in experimental animals. The external route of progressive bacterial colonization extends from the cutaneous exit site through the dacron cuff and into the peritoneum. Bacterial growth along this route consists primarily of glycocalyx enclosed bacterial biofilms adherent to catheter and tissue surfaces, and this surface colonization may or may not give rise to peritoneal infection in which free-living bacteria are found in the peritoneal fluid. The rate of this progressive bacterial colonization depends on the degree of bacterial contamination of the exit site at the time of implantation. Exit site sterilization (hibitane) delays the process while inoculation with rabbit skin strains of Staphylococcus epidermidis accelerates it. Even with optimal implantation techniques, bacterial colonization proceeds via this subcutaneous route so that most Tenckhoff catheter surfaces are covered with a bacterial biofilm, consisting predominantly of gram positive cocci, within three weeks after the implantation of these devices. The rate of bacterial biofilm development on both surfaces of these Tenckhoff catheters, the bacterial colonization of peritoneal tissues, and the dissemination of bacteria into the peritoneal fluid are all significantly accelerated by dialysis in this experimental animal model of continuous ambulatory peritoneal dialysis (CAPD).