Over half of the tumors of the retroperitoneal space, discounting primary organ neoplasms, such as those of the kidneys and pancreas, are due to in volvement of the lymph nodes (2) . The tumors that involve the para-aortic nodes are the lymphomas and metastatic carcinomas, the latter predominantly from a primary uterine or testicular source. Disease of these nodes is of prognostic and therapeutic significance. The retroperitoneal nodes lie along the main vascular trunks. Because of their distance from the rinary and intestinal tracts, these nodes must attain a considerable size before deforming the pacified ureter or stomach and intestine. Aortograms seldom reveal changes from expanding retroperitoneal masses, while the opacified inferior vena cava commonly shows defects produced by adjacent tumors (Fig . 7). The pressure within the aorta makes this vascular structure impervious to change from an extrinsic mass. The inferior vena cava, being thin-walled and of low in traluminal pressure, is easily distort...