IgG4 Related Disease: Histopathological Findings, Investigations

IgG4 Related Disease

IgG4-related diseases will form tumor-like lesions (pseudotumors). These are formed due to the overexpression of immunoglobulin G4. IgG4 is produced from the plasma cells in larger quantities, and these plasma cells are infiltrated into the tissues. Tumefactive lesions will be seen. Various sites of the disease include 

• Salivary glands or parotid gland (Submandibular or sublingual)
• Lacrimal glands (Fungating variety)
• Thyroid gland
• Lungs
• Sausage pancreas
• Hepatobiliary involvement 

These two are historically important diseases. Recently, they have been categorized or presented under the Immunoglobulin G4 diseases. They will definitely involve the parotid glands. These diseases are:

1. Mikulicz syndrome: It is an outdated syndrome. It is a subtype of Sicca syndrome/ Sjogren's syndrome. The Standard presentations are Dry eyes and dry mouth. It has a progressive enlargement of parotid glands
2. Ormond Disease: This disease is removed from the books because it is part of the immunoglobulin G4-related diseases. A tumor or mass is present in the retroperitoneum, grows substantially, and causes retroperitoneal fibrosis. 

Histopathological Findings in IgG4 Related Disease

Blue color spots are the mononuclear infiltrate varieties found in the light microscope. Multiple fibrotic sites are present between the fibrotic bands in a crisscross fashion. It helps to differentiate the tumor from the pseudo-tumor. These findings include

• Storioform fibrosis 
• Infiltrate plasma cells
• Obliterative phlebitis (Damage to veins)

Investigations in IgG4-Related Disease

It is a pathology-based diagnosis. A Whole-body PET Scan is done, and a biopsy sample is also a choice. Values of IgG and IgG4  will increase 40 times the normal values.

CT abdomen is done if the mass is present in the peripheral region.

The big pancreas present in the image is known as a sausage pancreas. This type of pancreas is found in IGG4-related diseases.

Chest X-Ray 

A circumscribed mass is present on the right lower zone, which can be seen on the X-ray. The doctor will plan for an HRCT or bronchoscopy-guided biopsy by observing the circumscribed mass on the chest X-ray. The results show that there is no tumor. As it is a pseudotumor, steroids are recommended. 

This tumor is known to be a plasma cell infiltration in the tissues

Bronchoscopy is not recommended if the mass is located in the peripheral region

Clinical Findings in IgG4-Related Disease

It is more common in Males, and rheumatological disorders are more common in women. An eyelid or orbital mass will increase in size (Pseudotumor). Submandibular gland enlargement (which has subsequently turned out to be a pseudotumor)or a thyroid mass can be present.

Fibrosis found in the thyroid gland is Riedel thyroiditis, which has a Stony hard consistency.

On the chest X-ray, lung pseudotumor can be present. To treat IgG4-related diseases, steroids, and Rituximab can be administered on a long-term basis. The tumor size will decrease. Sausage pancreas is an Incidental finding of Retroperitoneal fibrosis. 

If any of the above findings are present in the biopsy, rule out the possibility of the tumor.

Treatment of IgG4-Related Disease

Steroids and anti-CD molecules like Rituximab can be used for the treatment of IgG4-related diseases.

Frequently Asked Questions 

Q: What is the Treatment of IgG4-Related Disease?

Answer: Steroids and anti-CD molecules like Rituximab can be used for the treatment of IgG4-related diseases

Q: What are the main clinical features of Sicca syndrome/ Sjogren's syndrome?

Answer: The Standard presentation is Dry eyes and dry mouth.

Q: What are the reasons for the development of tumor-like lesions (pseudotumors) in IgG4-related diseases?

Answer: Pseudotumors are formed due to the overexpression of immunoglobulin G4.

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