What Is Granuloma?

Overview

Granuloma is an aggregation of immune cells and other tissues that is found in any part of the body, including the lungs, skin, liver, spleen, or gastrointestinal tract. These tiny clusters are not cancerous; they are benign lesions that are formed as a response to chronic inflammation, infection, or irritation. Granuloma is a defensive mechanism the body uses to ward off infection and prevent foreign invaders from spreading within the body. When a foreign substance, such as bacteria, parasites, or fungi, enters the body, the immune system responds by sending immune cells to the affected area to eliminate the infection, and the cells cluster together, forming granulomas.³ 

Types of granuloma

There are different types of granulomas occurring in various parts of the body, according to the cause of granuloma development. Some types of granulomas include: 

Tuberculosis granuloma 

Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis, and it is the most frequent cause of granulomas. It contains a central core of necrosis and is surrounded by immune cells such as macrophages and lymphocytes.^1,2 

Foreign body granulomas

Foreign materials trigger an immune response, leading to granuloma formation. Foreign body granulomas commonly occur in response to surgical sutures, bee stings, spider bites, injections, or any substance that irritates the body.

Sarcoid granuloma 

Sarcoidosis is a rare inflammatory condition that results in swollen tissues called granulomas. These granulomas affect the lungs, liver, lymph nodes, eyes, or skin.

Granuloma annulare 

Granuloma annulare is a benign skin disease characterised by small, raised bumps under the skin. It affects patients at any age and is more common in people under the age of 30. The exact cause of granuloma annulare is unknown but is most probably due to a reaction to different triggers.

Crohn’s granulomas 

Granuloma is considered the hallmark of the diagnosis of Crohn’s disease. Crohn’s disease is a chronic inflammatory bowel condition affecting the colon, leading to the development of granulomas in the gastrointestinal tract.

Wegener’s granulomatosis 

Wegener’s granulomatosis, or granulomatosis with polyangiitis, is an autoimmune disorder characterized by the presence of granulomas and inflammation of the blood vessels.

Pyogenic granuloma 

Pyogenic granuloma is a common benign vascular lesion affecting the skin and oral mucous membrane. It occurs due to local irritation or trauma.

Causes of granuloma

Granulomas are a response to chronic inflammation, and a wide range of triggers can result in granuloma formation. These may be infectious triggers or non-infectious triggers: 

1. Infections

Infection is considered the most common cause of granulomatous inflammation. Granuloma development is triggered by certain infections, such as bacterial infections like tuberculosis, fungal infections like histoplasmosis or coccidioidomycosis, and parasitic infections such as schistosomiasis.³ 

2. Inflammation 

Granuloma may develop as a response to inflammation in Crohn's disease and inflammatory bowel disease. 

3. Autoimmune disease 

Rheumatoid arthritis is an autoimmune and inflammatory disease that may be characterized by granulomatous inflammation.

4. Immunodeficiency diseases

Chronic granulomatous disease is a rare inherited immunodeficiency disease that leads to infections, inflammation, and granulomatous formation.

5. Foreign body 

Splinters and sutures may trigger granuloma formation. 

Signs and symptoms of granuloma

Granulomas occur in different parts of the body, due to several underlying diseases and cofactors. So, the signs and symptoms of granuloma vary depending on the cause and location of the granuloma. Some of the signs and symptoms include: 

1. Granulomas of the lung cause respiratory symptoms, including cough, fever, difficulty breathing, chest pain, and wheezing. Symptoms may be more serious and affect lung function if the granulomatous mass is large.⁴
2. Granulomas may be formed in the gastrointestinal tract, as in Crohn's disease, where granulomas are formed in the colon and present with abdominal pain, bloody diarrhoea, rectal bleeding, fatigue, and weight loss.
3. Skin granuloma is characterised by yellowish or reddish, raised, thickened bumps or nodules on the skin. The shape, size, and number of lesions may vary.
4. Eye problems, as in the case of ocular sarcoidosis, include blurred vision, light sensitivity (photophobia), and eyes which may feel dry, itchy,   painful, or with a burning sensation. You may also notice floaters, which are black spots or lines in the vision, which may develop into vision loss.
5. Rheumatoid granuloma is characterised by granulomas localised at pressure points near the joints, causing joint pain, swelling, stiffness, and motion limitation.⁵ 

Diagnosis

The diagnosis of granuloma involves taking medical history, conducting clinical examinations, and performing diagnostic tests.

1. Medical history

Includes family history or exposure to any risk factors that may trigger granuloma formation.

2. Physical examination 

The physician will evaluate the size, shape, and location of the granuloma. Especially in cases of skin granulomas, a physical examination is essential to confirm the diagnosis. 

3. Blood tests

Blood tests may be conducted to measure inflammatory markers or autoimmune markers. 

4. Imaging tests

Radiographic examination using imaging tests such as X-rays and CT scans can help in visualising the granulomas and assessing their location and extent. 

5. Biopsy 

A biopsy (taking out a small piece from the granuloma for checking under a microscope) may be necessary to confirm the diagnosis and determine the underlying cause.

Management and treatment for granuloma

Treatment options for granuloma vary according to the location, extent, and underlying cause of granuloma. 

The first step in the effective management of granuloma is to identify the cause, whether it is an infection, an autoimmune disease, or inflammation due to a foreign body.⁶ Treatment includes medications or surgical management. 

Medications:

• Antibiotics or antifungals: if an infection is the root cause of the granuloma, antibiotics or antifungal medications are prescribed
• Anti-inflammatory drugs: corticosteroids such as prednisone reduce inflammation associated with granulomas. In the case of sarcoidosis, most lesions get better over 3 years without treatment, but in cases of progressive disease, corticosteroids are prescribed and required for 6 to 12 months or even longer 
• Immunosuppressants: medications such as methotrexate or azathioprine are used to control an immune response

Surgical intervention: 

• Surgical removal is an available treatment approach. In some cases, surgical removal of the granuloma may be necessary when the granuloma causes symptoms, obstructs vital structures, or has a risk of malignancy

FAQs

How can I prevent granuloma?

Tips to prevent granulomatous inflammation: 

1. Avoid exposure to irritants such as foreign substances that trigger the formation of granulomas.
2. Avoid exposure to infections by maintaining healthy immunity.
3. Seek medical advice if you have an autoimmune disease or chronic infection that increases the risk of granuloma formation since regular checkups may be required. 

How common is granuloma?

The prevalence of granuloma varies according to the type of granuloma: 

• Granuloma is considered the main diagnostic microscopic picture in Crohn's disease, where it is detected in up to 60% of patients.⁹ 
• Sarcoidosis rates vary depending on the region of the world. In the UK, the prevalence of sarcoidosis is 11 per 100,000.⁷
• Wegener’s granulomatosis is a rare disease, the incidence of Wegener’s granulomatosis is 11.8 per million people every year.⁸
• The prevalence of formation of foreign body granuloma depends on factors including frequency of exposure to foreign body and individual susceptibility. 
• Chronic granulomatous disease prevalence is estimated between 1/100,000 and 1/217,000 worldwide.

Who is at risk of granuloma?

Patients at risk are those with chronic medical conditions, autoimmune diseases, and high risk of exposure to infections and irritants. 

When should I see a doctor?

It is necessary to see a doctor if you suspect the presence of a granuloma or if you experience any signs or symptoms like those mentioned below. 

• Skin abnormalities such as skin lesions, bumps, or nodules that do not heal and have a tendency to grow. 
• Respiratory symptoms like wheezing, cough, chest pain and shortness of breath. 
• In case of underlying conditions such as tuberculosis and Crohn's disease
• Unexplained weight loss, fatigue and fever.

Summary

Granuloma is a defensive mechanism by the immune system to prevent the spread of invaders in the body. There are different types of granulomas depending on the location, cause and associated underlying condition. Each granuloma type has a variety of signs, symptoms and treatment strategies. 

Proper diagnosis is the key to determining which treatment option is appropriate for each case. Overall, prevention is key, such as taking care of overall health, maintaining good hygiene, preventing exposure to infection, and closely monitoring chronic conditions.