IgG4-Related Disease
IgG4-Related Disease
Also known as:IgG4-RD; IgG4-related systemic disease; China First Rare Disease Catalog item 56
IgG4-related disease is a chronic immune-mediated fibroinflammatory condition that can affect multiple organs, characterized by IgG4-positive plasma cell infiltration and fibrosis, often presenting as painless masses or organ enlargement, and usually responding well to glucocorticoid therapy.
Start Here
A quick guide to the next step: which department to start with, what to prepare, and what to ask.
Rheumatology for evaluation of unexplained organ enlargement or mass; gastroenterology, urology, or ophthalmology may be needed depending on organ involvement.
An immune-mediated disease where IgG4-positive plasma cells infiltrate and damage multiple organs, causing inflammation, fibrosis, and tumor-like masses that can mimic cancer.
Glucocorticoids are first-line and most patients respond well; rituximab and other immunosuppressants are used for relapsing or refractory disease.
The exact cause is unclear; likely involves genetic susceptibility and environmental triggers; not a typical single-gene disorder.
Symptoms vary by organ and are often mistaken for cancer, infection, or isolated organ diseases; tissue biopsy is usually required for diagnosis.
Common Search and Care Questions
This page helps patients and families organize care leads. It does not replace a clinician’s diagnosis or treatment plan. For testing, medication, referrals, emergency care, and support applications, follow qualified clinicians, medical institutions, support organizations, and official sources.
Diagnosis Path
Organized around the practical patient journey: identify clues, avoid common delays, then prepare for care.
When to Suspect It
- Painless lacrimal or salivary gland enlargement (Mikulicz disease).
- Autoimmune pancreatitis (type 1 AIP) with pancreatic mass or obstructive jaundice.
- Retroperitoneal fibrosis causing hydronephrosis or abdominal pain.
- Unexplained lymphadenopathy, orbital mass, or hypopituitarism.
- Multiple organs involved simultaneously or sequentially.
Common Wrong Turns
- Performing surgery for organ enlargement without biopsy to exclude IgG4-RD.
- Treating autoimmune pancreatitis as pancreatic cancer with Whipple surgery.
- Diagnosing based solely on elevated serum IgG4 without histopathologic confirmation.
- Managing retroperitoneal fibrosis only as ureteral stenosis without systemic evaluation.
Departments to Start With
- Rheumatology
- Gastroenterology (pancreatic/biliary involvement)
- Urology (retroperitoneal fibrosis/hydronephrosis)
- Ophthalmology (orbital/lacrimal involvement)
- Pathology (tissue biopsy for diagnosis)
Before the Visit
- Document timeline of organ involvement and symptom evolution.
- Serum IgG4 level (elevated in most, but not required for diagnosis).
- Imaging of involved organs (CT/MRI/PET-CT).
- Tissue biopsy: lymphoplasmacytic infiltrate rich in IgG4+ plasma cells (>10/HPF), storiform fibrosis, obliterative phlebitis.
- Exclude malignancy, infection, and other autoimmune diseases.
Tests to Ask About
- Serum IgG4 level.
- Imaging of involved organs (CT/MRI).
- Tissue biopsy with IgG4 immunohistochemistry.
- Autoantibody and infection workup (to exclude mimics).
- PET-CT (to assess extent of systemic involvement).
Questions for the Doctor
- Is my lesion IgG4-RD or cancer? What did the biopsy show?
- How long will I need steroids? What is the relapse rate?
- Which organs need long-term monitoring?
- When is rituximab considered?
- Are there dietary or lifestyle recommendations?
Basic Information
Medical Notes
More complete medical explanations are kept here for discussion with clinicians.
Symptoms
Symptoms vary by involved organ. Common manifestations include type 1 autoimmune pancreatitis (painless pancreatic enlargement, obstructive jaundice), Mikulicz disease (symmetric lacrimal and salivary gland enlargement), retroperitoneal fibrosis (flank pain, hydronephrosis), orbital disease (proptosis, visual impairment), sclerosing cholangitis (jaundice, pruritus), tubulointerstitial nephritis (renal dysfunction), hypophysitis (diabetes insipidus, endocrine dysfunction), pulmonary involvement (cough, dyspnea), and lymphadenopathy. Systemic symptoms such as fever are uncommon and should raise concern for infection or other conditions.
Diagnosis
The 2019 ACR/EULAR classification criteria integrate clinical, radiologic, serologic, and pathologic features. Histopathology is central: dense lymphoplasmacytic infiltrate rich in IgG4+ plasma cells (>10 per high-power field and IgG4/IgG ratio >40%), storiform fibrosis, and obliterative phlebitis. Elevated serum IgG4 (>135 mg/dL) is supportive but not required, as about 30% of patients have normal levels and other conditions can also elevate IgG4. Biopsy is essential to exclude lymphoma, carcinoma, infection (e.g., tuberculosis), and other autoimmune diseases (e.g., sarcoidosis, Sjögren syndrome).
Treatment
Glucocorticoids are the first-line therapy for induction of remission, typically prednisone 30–40 mg/day with gradual taper over weeks to months. Approximately 70–90% of patients respond. For relapsing, steroid-dependent, or steroid-intolerant disease, rituximab (anti-CD20 monoclonal antibody) or other immunosuppressants (azathioprine, mycophenolate mofetil, tacrolimus) are used. The goal is to induce and maintain remission, prevent organ damage, and halt fibrotic progression. Regular monitoring of serum IgG4 and imaging is needed to detect relapse.
Long-term Care
Relapse occurs in 20–50% of patients, necessitating long-term follow-up. Monitoring includes symptom review, serum IgG4, and imaging of involved organs. Even with normal serum IgG4, active disease may persist, so imaging is important. Watch for medication side effects (osteoporosis, hyperglycemia, infection risk with steroids and rituximab). Patient education includes recognizing signs of relapse and avoiding unsupervised medication discontinuation.
Fertility and Family
IgG4-RD is not a classic genetic disorder; familial clustering is rare. Family planning should occur during disease quiescence, with rheumatology consultation regarding medication safety (e.g., rituximab in pregnancy).
When to Seek Urgent Care
Severe obstructive jaundice with fever (possible cholangitis), acute renal failure, rapid visual loss, severe abdominal pain with signs of bowel obstruction require immediate emergency care.
Prognosis
Most patients respond well to steroids; relapse is common and requires long-term monitoring; early diagnosis and treatment improve organ function and outcomes.