IgG4-Related Disease (IgG4-RD) is a chronic inflammatory condition characterised by the infiltration of IgG4-positive plasma cells and T lymphocytes into various tissues, leading to fibrosis and the formation of tumour-like masses. This condition can affect virtually any organ system, making it a highly versatile and potentially systemic disorder. Understanding IgG4-RD is crucial for early diagnosis and effective management.
Symptoms of IgG4-Related Disease
The symptoms of IgG4-RD vary widely depending on the organs involved. It can present as a single-organ disease or as a multisystemic condition.
Common Symptoms
- Mass Lesions – Tumor-like swellings or masses in affected organs, which can be mistaken for malignancies.
- Pain and Swelling – Generalized pain and swelling in affected areas, such as salivary glands, lymph nodes, or pancreas.
- Constitutional Symptoms – Fever, weight loss, and fatigue.
Organ-Specific Symptoms
- Pancreas (Autoimmune Pancreatitis) – Abdominal pain, jaundice, weight loss, and symptoms of pancreatic insufficiency (e.g., steatorrhea).
- Salivary and Lacrimal Glands (Mikulicz’s Disease) – Swelling of the parotid, submandibular, and lacrimal glands, leading to dry mouth and dry eyes.
- Biliary Tract – Symptoms of biliary obstruction, such as jaundice and pruritus.
- Kidneys – Renal insufficiency, hematuria, and proteinuria due to tubulointerstitial nephritis.
- Retroperitoneum – Retroperitoneal fibrosis causing back pain, renal dysfunction, and urinary obstruction.
- Lungs – Cough, shortness of breath, and chest pain due to lung nodules or interstitial lung disease.
Causes of IgG4-Related Disease
The exact cause of IgG4-RD is not well understood, but it is believed to involve an abnormal immune response.
Immune Mechanisms
- IgG4 Antibodies – Elevated serum levels of IgG4 and tissue infiltration by IgG4-positive plasma cells are hallmarks of the disease.
- Autoimmune Response – The condition is considered autoimmune in nature, with the immune system attacking the body’s own tissues.
Genetic and Environmental Factors
- Genetic Predisposition – Certain genetic factors may increase susceptibility to IgG4-RD.
- Environmental Triggers – Infections or other environmental factors may trigger the disease in genetically predisposed individuals.
Diagnosis of IgG4-Related Disease
Diagnosing IgG4-RD involves a combination of clinical evaluation, laboratory tests, imaging studies, and biopsy.
Clinical Evaluation
- Symptom Review – Detailed discussion of symptoms, including the location and nature of masses, pain, and systemic symptoms.
- Physical Examination – Assessment of affected organs for swelling, masses, and functional impairment.
Diagnostic Tests
- Blood Tests:
- Elevated serum IgG4 levels, though not specific, can support the diagnosis.
- Elevated inflammatory markers, such as ESR and CRP.
- Imaging Studies:
- Elevated serum IgG4 levels, though not specific, can support the diagnosis.
- Elevated inflammatory markers, such as ESR and CRP.
Biopsy
- Tissue Biopsy:
- Confirmation of diagnosis by demonstrating IgG4-positive plasma cell infiltration and characteristic fibrosis in the affected tissue.
- Histopathological examination showing storiform fibrosis, obliterative phlebitis, and a dense lymphoplasmacytic infiltrate.
IgG4-Related Disease Treatment
The treatment of IgG4-RD aims to reduce inflammation, manage symptoms, and prevent organ damage.
Medications
- Corticosteroids – Prednisone is commonly used as the first-line treatment to reduce inflammation and immune activity.
- Immunosuppressive Drugs – Azathioprine, mycophenolate mofetil, and methotrexate are used to maintain remission and reduce steroid dependency.
- Biologic Agents – Rituximab, a monoclonal antibody that targets B cells, can be effective in refractory cases or when corticosteroids are contraindicated.
Monitoring and Follow-Up
- Regular Check-Ups – Frequent visits to a healthcare provider to monitor disease activity, treatment response, and potential side effects of medications.
- Laboratory Tests – Regular blood tests to monitor IgG4 levels and inflammatory markers.
Living with IgG4-Related Disease
Managing IgG4-RD involves ongoing care, lifestyle adjustments, and support to maintain quality of life.
Self-Care Strategies
- Adherence to Treatment – Following prescribed medication regimens and attending all medical appointments.
- Healthy Diet – Consuming a balanced diet supports overall health and reduces inflammation.
- Regular Exercise – Engaging in physical activity as tolerated to maintain strength and mobility.
While IgG4-Related Disease is a complex and potentially systemic condition, effective management strategies can help control symptoms, prevent organ damage, and improve quality of life. Staying informed, adhering to treatment plans, and maintaining a proactive approach to health and well-being are key to living well with IgG4-RD.
