What Are Granulomas?

Medically Reviewed By Meredith Goodwin, MD, FAAFP
Was this helpful?
2

Granulomas are small, concentrated areas of inflammation. They are made up of immune cells clumped together and are usually noncancerous. Granulomas tend to occur in the lungs, but they can appear anywhere in the body. 

This article discusses what granulomas are, how they form, symptoms, and treatment options. 

What is a granuloma?

woman laying on bed
Francesca Russell/Stocksy United

Granulomas are focalized areas of white blood cells called macrophages. White blood cells are a primary part of the immune response and are responsible for actions such as attacking pathogens, including viruses and bacteria. 

Macrophages often engulf, or “eat,” pathogens, and it is thought that granulomas are from an ancient evolutionary infection response to protect the body.

Granulomas were first discovered in people with tuberculosis in the 1600s. They commonly form in the lungs, such as in tuberculosis, but they can form in other areas of the body as well. 

A granuloma forms because of a prolonged response to ongoing stimuli. It is the body’s way to contain or stop the spread of bacteria or an infection.

Are granulomas cancerous? 

Granulomas are not

usually cancerous, but they can be associated with different complications and conditions, including sarcoidosis and noncancerous conditions such as Crohn’s disease.

What causes a granuloma?

Granulomas form when the body encounters a foreign “invader.” This could be something infectious or noninfectious. For instance, granulomas can form in response to infections, autoimmune conditions, toxins, allergies, drugs, and neoplastic conditions. 

When the foreign invader is detected, the body’s immune response is triggered. The immune response process sends macrophages to the area where the foreign body has been detected, and they “huddle” around the invader. However, when the white blood cells cannot kill the invader, they instead form a protective coating around it. 

Granulomas form and remain in the body as a clump of macrophages around the initial pathogen. Granulomas can be isolated or occur in groups.

Most common sites for granulomas 

The most common site for a granuloma is the lungs. 

However, granulomas can also form in the:

  • skin
  • kidneys
  • liver
  • lymph nodes
  • eyes 
  • vocal cords

Sarcoidosis

Granulomas can be associated with an inflammatory disease called sarcoidosis. This is a granulomatous disease that affects several organ systems in the body, including the lungs, kidneys, skin, joints, muscles, and eyes. 

Sarcoidosis leads to granulomas forming in different organ systems. The American Lung Association (ALA) notes that the symptoms of this disease will be different for every person but typically include:

The symptoms of sarcoidosis are very general, so the condition tends to be difficult to diagnose. In fact, the ALA explains that most cases go undiagnosed for years. 

Sarcoidosis most commonly occurs in Black females and first appears in the lungs. It is thought that sarcoidosis begins as a result of the immune response to a bacterial infection or unknown environmental trigger. 

Learn more about sarcoidosis here.

Immune responses

Granulomas form as part of the immune response to different infectious and noninfectious triggers in the body. These triggers can include

  • Mycobacteria: Mycobacteria are the most common source of granulomas. They are also the primary bacteria responsible for tuberculosis. 
  • Coccidioides species: These are fungi that cause coccidioidomycosis, or Valley Fever.
  • Mycobacterium leprae: These are tropical bacteria that cause Hansen’s disease, which is an infection that affects the skin, nerves, and sinus membranes. 
  • Mycosis fungoides: This is a very rare subtype of non-Hodgkin lymphoma
  • Crohn’s disease: Granulomas can occur in some people with Crohn’s disease. 

What are the symptoms of a granuloma? 

A granuloma may not cause any symptoms at all. 

Symptoms may not appear unless the granuloma develops into a larger condition or is located in an area of the body where it could cause complications, such as the lungs or intestines.

Granulomas in the lungs could lead to symptoms such as:

Granulomas in the intestines could cause symptoms such as:

How do you treat a granuloma?

Granulomas may not need treatment unless the symptoms they are causing are severe or they are part of a larger condition. 

If there are symptoms that require treatment, it depends on where the granulomas are and what is causing them. For example, granulomas in the lungs may need a different treatment approach than granulomas in the intestines.

In general, doctors may treat granulomas with anti-inflammatory medications or topical agents.

Can granulomas go away by themselves?

In some situations, granulomas can heal on their own without any treatment. For instance, the American Academy of Dermatology explains that granulomas in the skin often do not require any treatment. 

Granulomas may also stay in the body without causing complications. 

Diagnosis 

If granulomas are inside the body, such as in the lungs or stomach, imaging tests can help a doctor diagnose them. Granulomas in the skin may require a skin biopsy to rule out other conditions. 

In all cases, a doctor may also order other tests, such as blood work, to look for other conditions that may be causing the symptoms. 

Types of granulomas 

There are many different types of granulomas. They range from isolated granulomas to granulomas that are part of larger conditions, such as Crohn’s disease, tuberculosis, or sarcoidosis. 

A necrotizing granuloma is one where the tissue is dead. A necrotic granuloma often looks fluid-filled on a chest X-ray.

However, in general, granulomas are divided into two categories: caseating and non-caseating. Caseating granulomas have a central place of necrosis and tend to occur in response to a mycobacterial or fungal infection in the lungs. Non-caseating granulomas do not have central necrosis

Outlook

In many cases, granulomas are not dangerous. However, depending on the cause and location of the granulomas, they can lead to complications.

Additionally, granulomas can also occur in more serious conditions and diseases, such as tuberculosis, Crohn’s disease, and sarcoidosis. 

Summary

Granulomas are localized areas of white blood cells that can occur anywhere in the body. However, they are most often present in the lungs. They are not usually cancerous, and they may not have symptoms or cause complications. 

That said, granulomas can be associated with different conditions that could cause symptoms and complications. Doctors treat granulomas on a case-by-case basis depending on what symptoms are present. In some situations, no treatment is necessary. 

Was this helpful?
2
Medical Reviewer: Meredith Goodwin, MD, FAAFP
Last Review Date: 2022 Mar 29
View All Lungs, Breathing and Respiration Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.