Retroperitoneal fibrosis
Retroperitoneal fibrosis or Ormond's disease is a disease featuring the proliferation of fibrous tissue in the retroperitoneum, the compartment of the body containing the kidneys, aorta, renal tract, and various other structures. It may present with lower back pain, kidney failure, hypertension, deep vein thrombosis, and other obstructive symptoms. It is named after John Kelso Ormond, who rediscovered the condition in 1948. Causes. Its association with various immune-related conditions and response to immunosuppression have led to speculation regarding an autoimmune cause of idiopathic RPF. One-third of the cases are secondary to malignancy, medication (methysergide, hydralazine , beta blockers), aortic aneurysm, or certain infections. Diagnosis. The diagnosis of retroperitoneal fibrosis cannot be made on the basis of the results of laboratory studies. CT is the best diagnostic modality: a confluent mass surrounding the aorta and common iliac arteries can be seen. On MRI, it has low T1 signal intensity and variable T2 signal. Malignant retroperitoneal fibrosis usually give uneven MRI signals, bulky, extend above the origins of renal arteries, or displace aorta anteriorly. Besides, malignant retroperitoneal fibrosis less frequently displaces ureter medially when compared to other retroperitoneal fibrosis. On fludeoxyglucose (18F) (FDG) positron emission tomography (PET ) scan, it will show accumulation of FDG in the affected area. Although biopsy is not usually recommended, it is appropriate when malignancy or infection is suspected. Biopsy should also be done if the location of fibrosis is atypical or if there is an inadequate response to initial treatment. Treatment. In the absence of severe urinary tract obstruction (which generally requires surgery with omental wrapping), treatment is generally with glucocorticoids initially, followed by DMARDs either as steroid-sparing agents or if refractory on steroids. The SERM tamoxifen has shown to improve the condition in various small trials, although the exact mechanism  of its action remains unclear. Associations include: