[Retroperitoneal fibrosis].

The inflamed tissue characteristic of retroperitoneal fibrosis typically causes gradually increasing pain in the lower abdomen, back, or side. Other symptoms arise from blockage of blood flow to and from various parts of the lower body, due to the development of scar tissue around blood vessels. The fibrosis usually develops first around the aorta, which is the large blood vessel that distributes blood from the heart to the rest of the body. Additional blood vessels including the inferior vena cava, which returns blood from the lower part of the body to the heart, may also be involved. Obstruction of blood flow to and from the legs can result in pain, changes in color, and swelling in these limbs. Impairment of blood flow in the intestines may lead to death (necrosis) of intestinal tissue, severe pain, and excessive bleeding (hemorrhage). In men, reduced blood flow back toward the heart (venous flow) may cause swelling of the scrotum.