Learning Radiology xray montage

Retroperitoneal Fibrosis

· General considerations

o       Relatively uncommon

o       More common in males than in females

o       Predominantly patients aged 40-60 years

o       In almost 70% of patients, no cause is found

· Primary or Idiopathic Retroperitoneal Fibrosis (RPF)

o       May be an autoimmune response to ceroid, an insoluble lipid that can leak through a thinned arterial wall from atherosclerotic plaques

§         Leads to a vasculitis

o       Also found in association with other fibrosing diseases suggesting auto-immune mechanism

§         Primary biliary cirrhosis

§         Fibrosing mediastinitis

§         Glomerulonephritis

§         Panhypopituitarism

§         Rheumatoid arthritis

§         Ankylosing spondylitis

§         Polyarteritis nodosa

§         Systemic lupus erythematosis (SLE)

§         Hashimoto thyroiditis

·         Secondary Retroperitoneal Fibrosis

o       Has been found associated with certain drugs, such as

§         Methylsergicide

§         Beta-adrenergic blockers

§         Lysergic acid diethylamide (LSD)

§         Methyldopa

§         Amphetamines

§         Phenacetin

§         Hydralazine

§         Cocaine

o       Desmoplastic response to malignancy

§         Lymphoma

§         Carcinoid

§         Retroperitoneal metastases (breast, lung, thyroid, GI tract, GU organs)

o       Retroperitoneal fluid collection as in trauma, surgery or infection

o       Aneurysm of the aorta or iliac arteries (desmoplastic response)

o       Radiation therapy

·         Pathology

  Mass of whitish, dense, fibrous tissue covering the aorta, vena cava, ureters, and psoas muscles

o       Center of disease is usually located at the level of the 4th or 5th lumbar vertebra just at the aortic bifurcation

·         Clinical findings

o       Most common presentation is flank, back, scrotal or lower abdominal pain

o       Fever

o       Weight loss

o       Nausea and vomiting

o       Symptoms relating to renal impairment and hypertension are common clinical features

·         Imaging Findings

o       On excretory or CT urography

§         Medial deviation of the ureter beginning at the level of the L3 or L4 (DDx: aortic aneurysm, bladder diverticulum, abdominoperineal resection)

·         Not a constant feature

·         Most retroperitoneal masses displace ureters laterally

§         Proximal ureterectasis and pyelocaliectasis

§         Tapering of ureters distal to mass

o       On CT scans

§         Rind of soft tissue around aorta and inferior vena cava between level of kidney and sacrum

§         Spreads to involve the ureters, causing varying degrees of obstruction.

§         Fat plane between the mass and the psoas muscle may be obliterated

§         Unlike adenopathy, RPF tends not to displace aorta anteriorly

§         Mass may show varying degrees of enhancement depending on the stage of the disease

o       CT features-benign vs. malignant masses

§         Mass in RPF is less bulky than most neoplastic lesions

§         Malignancy produces enlarged mesenteric nodes and displacement of the aorta from the spine

§         Most retroperitoneal neoplasms displace the ureters laterally

o       US

§         Hypoechoic homogeneous mass

o       MRI

§         Low to medium homogeneous signal intensity on T1

§         Heterogeneous high signal intensity on T2 (inflammatory stage)

§         Low signal intensity on T2 (dense fibrotic stage)

·         Treatment

o       Use of steroids in RPF is controversial

o       Surgical ureterolysis

o       Immunosuppressive drugs

·         Prognosis

o       Satisfactory if renal impairment is not too severe

Retroperitoneal Fibrosis. There is a thick rind of soft tissue surrounding the aorta from the level of the kidneys (top photo-yellow arrow) to and including the bifurcation (bottom photo-red arrow). The soft tissue enhances slightly. Notice the aorta is not displaced forward as it would more likely be in lymphoma.
The left ureter (green arrow) is dilated.

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Ali Nawaz Khan, Muthusamy Chandramohan and Sumaira Macdonald eMedicine
Dahnert 4th Edition