IgG4-related disease (IgG4-RD), also known by several other names, is a condition that can affect multiple parts of the body and involves inflammation and abnormal growths, the cause of which is unknown. Any organ can be affected by this disease, but it’s commonly found in the pancreas, kidneys, certain structures around the eyes, salivary glands, and area behind the abdominal cavity.

The key feature of this disease is the presence of a high number of specific immune cells (IgG4 positive plasma cells) mixed with other immune cells and scar tissue, causing blood vessel obstruction and attracting a certain type of white blood cell (eosinophils). This condition often elevates the levels of a specific type of protein (IgG4) in the blood. The disease pattern looks similar across different organs which makes it resemble another disease called systemic sarcoidosis.

Because the abnormal growths caused by IgG4-RD can look similar to tumors, infections, or immune system diseases, it’s often misdiagnosed as cancer. Even though it’s frequently not recognized due to the lack of a comprehensive approach in assessing it, patients generally recover well after receiving a specific type of medication called glucocorticosteroids. In fact, the effectiveness of these steroids in treating IgG4-RD is so powerful that it could be used to help diagnose the disease.

The exact cause of this condition isn’t completely understood, but it’s believed to have links to several factors. These include a person’s genetic makeup, bacterial infections that can cause the body to mistakenly attack its own cells (a process called molecular mimicry), and autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues and organs.

The exact number of people affected by IgG4-related disease (IgG4-RD) is not certain.

The conditions similar to IgG4 related disease that doctors might need to rule out include:

  • Autoimmune pancreatitis
  • Eosinophilia
  • Hypereosinophilic syndromes
  • Lymphadenopathy
  • Multicentric Castleman disease
  • Orbital disease
  • Plasma cell neoplasm
  • Polyclonal hypergammaglobulinemia
  • Salivary and lacrimal gland enlargement
Frequently asked questions

IgG4-Related Disease (IgG4-RD) is a condition that can affect multiple parts of the body and involves inflammation and abnormal growths. It is characterized by the presence of a high number of specific immune cells (IgG4 positive plasma cells) mixed with other immune cells and scar tissue, causing blood vessel obstruction and attracting eosinophils. It is often misdiagnosed as cancer but can be effectively treated with glucocorticosteroids.

The exact number of people affected by IgG4-related disease (IgG4-RD) is not certain.

Signs and symptoms of IgG4-Related Disease can vary depending on the organs affected. However, some common signs and symptoms include: 1. Swelling and enlargement of affected organs: This can include the pancreas, salivary glands, lymph nodes, and other organs. The swelling may cause pain or discomfort in the affected area. 2. Fibrosis: IgG4-Related Disease can lead to the formation of excessive scar tissue, known as fibrosis, in the affected organs. This can cause organ dysfunction and further complications. 3. Fatigue and general malaise: Many individuals with IgG4-Related Disease experience fatigue, a general feeling of being unwell, and a lack of energy. 4. Allergic symptoms: Some people with IgG4-Related Disease may experience allergic symptoms such as itching, rash, or hives. 5. Organ-specific symptoms: Depending on the organs involved, individuals may experience specific symptoms. For example, those with pancreatic involvement may experience abdominal pain, jaundice, or digestive issues. It is important to note that the signs and symptoms of IgG4-Related Disease can mimic those of other conditions, making diagnosis challenging. If you are experiencing any of these symptoms, it is important to consult with a healthcare professional for a proper evaluation and diagnosis.

The exact cause of IgG4-Related Disease is not completely understood, but it is believed to have links to several factors such as genetic makeup, bacterial infections, molecular mimicry, and autoimmune diseases.

The conditions that a doctor needs to rule out when diagnosing IgG4-Related Disease include: - Autoimmune pancreatitis - Eosinophilia - Hypereosinophilic syndromes - Lymphadenopathy - Multicentric Castleman disease - Orbital disease - Plasma cell neoplasm - Polyclonal hypergammaglobulinemia - Salivary and lacrimal gland enlargement

The types of tests that a doctor may order to properly diagnose IgG4-Related Disease include: 1. Blood tests: These can measure the levels of IgG4 antibodies in the blood, as well as other markers of inflammation and organ damage. 2. Imaging tests: These can include CT scans, MRI scans, or ultrasound to visualize the affected organs and identify any abnormalities or swelling. 3. Biopsy: A tissue sample may be taken from the affected organ and examined under a microscope to look for characteristic features of IgG4-Related Disease, such as dense lymphoplasmacytic infiltrates and fibrosis. 4. Other tests: Depending on the specific organs involved, additional tests such as lung function tests, liver function tests, or kidney function tests may be ordered to assess the extent of organ damage.

IgG4-Related Disease is typically treated with corticosteroids, such as prednisone, to reduce inflammation and suppress the immune response. In some cases, other immunosuppressive medications may be used, such as azathioprine or rituximab. Treatment aims to control symptoms, prevent organ damage, and improve overall quality of life. In severe cases or when organ damage has occurred, surgery may be necessary to remove affected tissues. Regular monitoring and follow-up care are important to assess the effectiveness of treatment and manage any potential complications.

The side effects when treating IgG4-Related Disease can include: - Allergic reactions to medications - Increased risk of infections due to immunosuppressive therapy - Gastrointestinal symptoms such as nausea, vomiting, or diarrhea - Fatigue and weakness - Weight gain or fluid retention - Elevated blood sugar levels - High blood pressure - Mood changes or depression - Osteoporosis or bone fractures - Cataracts or other eye problems - Increased risk of certain types of cancer, although this is rare.

Patients generally recover well after receiving glucocorticosteroid medication. The effectiveness of these steroids in treating IgG4-RD is so powerful that it could be used to help diagnose the disease.

Rheumatologist.

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