Overview
IgG4-related retroperitoneal fibrosis (also called IgG4-RF or IgG4-related periaortitis/periarteritis) is a rare inflammatory disease where the immune system mistakenly triggers the buildup of scar-like tissue (fibrosis) in the retroperitoneum — the space behind the abdominal cavity that contains the kidneys, major blood vessels, and the tubes that carry urine from the kidneys to the bladder (ureters). This disease belongs to a broader family of conditions called IgG4-related disease (IgG4-RD), in which a type of immune protein called IgG4 plays a central role in causing inflammation and scarring in various organs. The growing fibrous tissue can wrap around and squeeze nearby structures, most commonly the ureters, which can block urine flow and damage the kidneys. It can also press on the aorta and other major blood vessels. People with this condition often feel vague back, flank, or abdominal pain for months before a diagnosis is made. Some people have no symptoms at all until organ damage has already occurred. The good news is that IgG4-related retroperitoneal fibrosis often responds well to treatment. Corticosteroids like prednisone are the main first-line therapy and can reduce inflammation and shrink the fibrous tissue significantly. In cases where steroids alone are not enough, other immune-suppressing medications may be added. Early diagnosis and treatment are key to preventing permanent kidney damage and other complications.
Also known as:
Key symptoms:
Dull, aching pain in the lower back, flank, or abdomenSwelling or discomfort in the belly areaDecreased urine output or difficulty urinatingSwelling in the legs due to blocked lymph or blood vesselsFatigue and general feeling of being unwellHigh blood pressure (sometimes caused by kidney involvement)Unintended weight lossMild feverNauseaKidney function decline detected on blood tests
Clinical phenotype terms (43)— hover any for plain English
Sporadic
Usually appears on its own, not inherited from a parent
Adult
Begins in adulthood (age 18 or older)
FDA & Trial Timeline
5 eventsHeidelberg University
Assistance Publique - Hôpitaux de Paris — PHASE4
Peking Union Medical College Hospital
Peking University International Hospital — PHASE2, PHASE3
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for IgG4-related retroperitoneal fibrosis.
5 clinical trialsare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to IgG4-related retroperitoneal fibrosis.
Community
No community posts yet. Be the first to share your experience with IgG4-related retroperitoneal fibrosis.
Start the conversation →Latest news about IgG4-related retroperitoneal fibrosis
Disease timeline:
New recruiting trial: Early Discontinuation of Steroid Treatment in Negative FDG-PET/CT Patients With Idiopathic Retroperitoneal Fibrosis
A new clinical trial is recruiting patients for IgG4-related retroperitoneal fibrosis
New recruiting trial: A Prospective Cohort Study of IRPF in China
A new clinical trial is recruiting patients for IgG4-related retroperitoneal fibrosis
New recruiting trial: National Registry of IRPF in China
A new clinical trial is recruiting patients for IgG4-related retroperitoneal fibrosis
New recruiting trial: Study of Sirolimus in Idiopathic Retroperitoneal Fibrosis
A new clinical trial is recruiting patients for IgG4-related retroperitoneal fibrosis
Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.How do you know this is IgG4-related and not another cause of retroperitoneal fibrosis, such as cancer?,How much kidney damage has already occurred, and is it reversible?,What is the plan if my disease comes back after I stop steroids?,Are there clinical trials I might be eligible for?,How long will I need to be on treatment, and what are the long-term risks?,Should I see a urologist to check whether my ureters need a stent?,What symptoms should prompt me to call you or go to the emergency room?
Common questions about IgG4-related retroperitoneal fibrosis
What is IgG4-related retroperitoneal fibrosis?
IgG4-related retroperitoneal fibrosis (also called IgG4-RF or IgG4-related periaortitis/periarteritis) is a rare inflammatory disease where the immune system mistakenly triggers the buildup of scar-like tissue (fibrosis) in the retroperitoneum — the space behind the abdominal cavity that contains the kidneys, major blood vessels, and the tubes that carry urine from the kidneys to the bladder (ureters). This disease belongs to a broader family of conditions called IgG4-related disease (IgG4-RD), in which a type of immune protein called IgG4 plays a central role in causing inflammation and scarr
How is IgG4-related retroperitoneal fibrosis inherited?
IgG4-related retroperitoneal fibrosis follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does IgG4-related retroperitoneal fibrosis typically begin?
Typical onset of IgG4-related retroperitoneal fibrosis is adult. Age of onset can vary across affected individuals.
Are there clinical trials for IgG4-related retroperitoneal fibrosis?
Yes — 5 recruiting clinical trials are currently listed for IgG4-related retroperitoneal fibrosis on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.
Which specialists treat IgG4-related retroperitoneal fibrosis?
23 specialists and care centers treating IgG4-related retroperitoneal fibrosis are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.