A granuloma is a cluster of white blood cells and other tissues that are generally not cancerous. They tend to develop in the lungs, on the head, or on the skin. Granulomas often go away on their own. However, treating underlying health conditions can also help clear them.

This article will explain what a granuloma is, how and why they develop, and how to treat them. It will also advise people on when it might be a good idea to talk with a doctor.

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A granuloma is a little lump, or nodule. It is a clump of immune cells or white blood cells.

Granulomas can be part of the immune system’s response to:

When the cells clump together, they protect the body from potential threats in two ways. The first is keeping an infection in one place to stop it from spreading to other parts of the body. The second is isolating an irritant or foreign object so it cannot do any further damage to the body.

Sometimes, long-term conditions such as Crohn’s disease and sarcoidosis can cause granulomas.

Granulomas are not cancerous.

There are different types of granulomas. They include:

Foreign body granulomas

When something penetrates the skin, eye, or other parts of the body, it can lead to a foreign body granuloma. This looks like a little lump at the site of the damage.

Things that can lead to foreign body granulomas include:

  • splinters
  • bee stings
  • spider bites
  • irritating substances, such as silica or some tattoo inks
  • injections, such as steroids, collagen, or vaccines
  • stitches

Skin granulomas

There are a few different types of skin granulomas.

Granuloma annulare

Granuloma annulare is a skin condition that causes bumps underneath the skin. The lumps are usually pink, yellow, or flesh-colored. They usually appear in the shape of a ring.

Granuloma annulare can affect any part of the body. They commonly appear on the:

  • fingers
  • hands
  • feet
  • elbows
  • legs

The lumps may appear on one part of the body only. Doctors call this localized granuloma annulare. Some people may experience lumps on more than one part of the body at a time. Doctors call this generalized or disseminated granuloma annulare.

Subcutaneous granuloma annulare

Subcutaneous granuloma annulare is often just one lump underneath the skin. It tends to affect children more than adults, and it does not hurt.

Subcutaneous granuloma annulare usually appear on:

  • the scalp
  • arms
  • legs

Perforating granuloma annulare

Perforating granuloma annulare causes lumps that develop a yellow center. People will often find a clear liquid leaking from the lumps before they crust over. The lumps can also join together to create a larger lesion.

Perforating granuloma annulare can leave a scar.

Linear granuloma

Linear granuloma is very rare. The lumps tend to develop in a line on the fingers.

Internal granulomas

Sometimes, granulomas can develop inside the body. They can affect the lungs, gut, or blood vessels.

Autoimmune diseases, or health conditions linked to the immune system, are the most common cause of internal granulomas.

The most common causes of granulomas are:

Immune response

Granulomas form when the body tries to protect itself from:

  • infection
  • inflammation
  • irritation
  • foreign bodies

White blood cells clump together at the area of the damage to isolate the threat. This can happen on the skin or inside the body.

People with tuberculosis, for example, will often have granulomas inside their lungs. This is the immune system’s way of stopping the Mycobacterium tuberculosis bacteria from spreading to other parts of the body.


Sarcoidosis is an autoimmune condition. That means it happens because of a fault in the immune system.

Sarcoidosis causes granulomas to form inside the organs for no reason. In around 90% of people with the condition, lumps grow in the lungs.

According to the Foundation for Sarcoidosis Research, having too many granulomas can interfere with the structure and function of organs. It can also lead to fibrosis, which is permanent scarring.

Doctors do not know what causes sarcoidosis. But there are some things that can make it more likely. Experts call these risk factors. They include:

  • being between the ages of 20 and 40 years
  • being African American
  • being of European, particularly Scandinavian, descent

Crohn’s disease

Crohn’s is also an autoimmune condition. It causes inflammation in the gastrointestinal tract, leading to a variety of symptoms, including:

  • pain
  • diarrhea and cramping
  • feeling and being sick
  • rectal bleeding

Some people with Crohn’s disease will develop granulomas in their gut.

Scientists do not know what causes Crohn’s disease. The risk factors include having a parent, child, or sibling with the condition, and being of Eastern European descent.

Granulomatosis with polyangiitis

Granulomatosis with polyangiitis is a rare disease.

It is a type of vasculitis, or inflammation in the blood vessels. Doctors used to call it Wegener’s granulomatosis. Granulomas develop in the blood vessels, making it difficult for blood to reach vital organs.

Common symptoms include:

  • joint pain
  • weakness and fatigue (lack of energy)
  • ongoing cold symptoms, such as a runny nose

Diagnosis will depend on where the granulomas are.

Doctors will usually only need to do a physical examination to diagnose skin granulomas. In most cases, they will also ask a few questions about the lumps, such as when they appeared.

To diagnose internal granulomas, doctors will need to understand the underlying cause of the problem. To do this, they may:

  • ask a series of questions about the person’s symptoms
  • carry out a blood test
  • carry out an imaging test, such as an X-ray or CT scan
  • carry out a genetic test
  • take a tissue sample by performing a needle biopsy

Treatment will depend on the underlying cause of the granuloma. In most cases, skin granulomas will go away on their own without treatment. Sometimes, though, they might come back.

Underlying health conditions can also cause granulomas. When this is the case, doctors will focus on treating the underlying cause of the lumps.

Granulomas are not cancerous.

Anyone with a granuloma that does not get better on its own, or that keeps coming back, should speak with a doctor.

People who feel they may have an underlying autoimmune disorder should also seek medical attention.

Granulomas are small clumps of immune cells. They are usually a normal part of the body’s immune system, working to isolate threats from the rest of the body.

They can develop anywhere on the body, including the skin, lungs, and other organs. They tend to go away on their own.

If someone has an autoimmune condition, such as Crohn’s disease or sarcoidosis, granulomas can develop for no reason.

Sometimes, they can damage the body and lead to scarring. When this is the case, doctors will usually recommend treating the underlying condition.

Granulomas are not cancerous.