Figure 1b. Retroperitoneal cystic lymphangioma in a 37-year-old man. (a) Photomicrograph (original magnification, x40; hematoxylin-eosin [H-E] stain) shows variable-sized thin-walled cystic spaces in the stroma that are lined with endothelial cells and contain lymphoid aggregation. (b) Contrast material-enhanced CT scan shows a low-attenuation mass in the right anterior pararenal space (arrow).