[Gastric cancer and obstructive uropathy]

In recent 5 years, we have experienced 24 cases of advanced gastric cancer associated with obstructive uropathy. Included were 19 cases of undifferentiated, 3 cases of differentiated and 2 cases of unknown histological type. Obstructive uropathy is diagnosed based on the typical radiological findings such as dilatation and delayed demonstration of the upper collecting systems. Pathologically, undifferentiated type of gastric cancer had tendency to spread infiltrating along the vessels, nerves and the lymphatics without alteration of the ordinary anatomical structures. In such cases, mucosal surface of the urinary tract tended to be spared in spite of extensive tumor invasion. It was proven that several radiological findings were characteristic of urinary tract involvement secondary to gastric cancer. Either thread-like ureteral stricture by IVU or ring-like appearance of the ureter by CT is one of those typical findings. Renal sinus involvement may occur continuously to diffuse retroperitoneal invasion and it appears as a thickened wall of renal pelvis or soft tissue mass directly extending into the fatty tissue of renal sinus by CT. In such cases IVU has less diagnostic ability because of the lack of mucosal destruction. If the urinary bladder is involved, it typically shows chestnut-bur appearance by IVU and diffuse wall thickening by CT. In cases of advanced gastric cancer, particularly in cases of histologically undifferentiated type, CT and IVU images should be carefully interpreted in consideration of the infiltrative art of tumor extension.