When lung tissue becomes inflamed from an infection or other cause, cells called histiocytes cluster to form nodules called granulomas. They may not cause any symptoms but may have an underlying cause that needs treatment.
Granulomas can form anywhere in your body but most commonly develop in your:
When granulomas first form, they’re soft. Over time, they can harden and become calcified. This means calcium is forming deposits in the granulomas. The calcium deposits make these kinds of lung granulomas more easily seen on imaging tests, such as chest X-rays or CT scans.
On a chest X-ray, some lung granulomas can potentially look like cancerous growths. However, granulomas are noncancerous and often cause no symptoms or require treatment.
While lung granulomas usually have no symptoms, their underlying cause may present symptoms.
No symptoms (asymptomatic)
There are seldom symptoms associated with lung granulomas themselves. They may not be discovered until an X-ray or CT scan is taken. Lung granulomas with no abnormal symptoms may not need to be treated.
If there are many granulomas or if they are located near the lung’s airways, the symptoms may include:
- coughs that don’t go away
- shortness of breath
- chest pain
- fever or chills
Symptoms related to underlying causes
Lung granulomas may form in response to respiratory conditions such as the following. In these cases, the underlying cause tends to present symptoms:
- Sarcoidosis. When this inflammatory disease affects the lungs, symptoms may include a dry cough, shortness of breath, and wheezing.
- Histoplasmosis. Symptoms of this lung infection include fever, dry cough, chest pain, and red bumps on your lower legs.
- Tuberculosis. If this bacterial disease is in the lungs, symptoms may include a chronic cough, coughing up blood or phlegm, and chest pain.
Infections, inflammatory diseases, and other factors such as the following are associated with lung granulomas.
Infections that could cause granulomas include:
- nontuberculous mycobacteria (NTM), found naturally in water and soil, are among the more common sources of bacterial infections that lead to lung granulomas
- fungal infections such as pulmonary coccidioidomycosis (valley fever) or cryptococcosis, which lives in soil with bird droppings
- parasitic infections such as roundworms (ascariasis)
- bacterial infections including aspiration pneumonia
Lung granulomas may be caused by the following inflammatory conditions:
- Granulomatosis with polyangiitis (GPA). This is a rare but serious type of vasculitis, inflammation of the blood vessels in your nose, throat, lungs, and kidneys. It’s unclear why this develops, though it may be an abnormal immune system reaction to an infection.
- Eosinophilic granulomatosis with polyangiitis (EGPA). Also known as Churg-Strauss syndrome, this is another type of vasculitis that may cause granulomas to form in the lungs.
- Sarcoidosis. An inflammatory issue in which inflammatory cells can form clumps in various organs like the lungs.
Exposure to environmental elements such as the following may cause lung granulomas:
- an allergic reaction, called hypersensitivity pneumonitis, to substances such as mold or chemicals
- exposure to dust from metals such as beryllium, aluminum, cobalt, or silica
- using a hot tub may cause what’s known as “hot tub lung” due to exposure to non-tuberculous mycobacteria (NTM)
- medications such as methotrexate, Enbrel, and Humira
Autoimmune diseases such as the following, which occur when your immune system mistakenly attacks healthy cells in your body, may cause lung granulomas:
- Rheumatoid arthritis (RA). Lung granulomas, also referred to as rheumatoid or lung nodules, occur in 20 percent of people with RA, a condition that causes joint pain and inflammation. They are usually harmless, but there’s a small risk that they can burst and harm your lung.
- Sjögren’s syndrome. Lung granulomas may occur with this condition that mostly affects the salivary and lacrimal glands, preventing your body from producing enough saliva and tears.
- Inflammatory bowel disease (IBD). According to a 2019 study, up to 36 percent of people with IBD had granulomas in their lungs or organs other than their gastrointestinal tracts.
Related to cancer
People with leukemia may develop lung granulomas due to lymphomatoid granulmatosis, a rare condition caused by the overproduction of lymphocytes, or white blood cells.
Lung granulomas are associated with some common variable immunodeficiency disorders (CVID) that prevent your body from fighting infections and diseases. These include:
- Chronic granulomatous disease (CGD). This rare, inherited condition affects certain white blood cells, causing inflammation and preventing your immune system from fighting bacterial and fungal infections.
- Granulomatous–lymphocytic interstitial lung disease (GLILD). This is a severe complication of CVID that can cause the long-term loss of respiratory function.
Another condition that may cause lung granulomas is pulmonary Langerhans cell histiocytosis (PLCH), a rare lung disease whose cause isn’t known. It most often affects
To diagnose lung granulomas and determine whether they are cancerous, your doctor will perform a physical exam and a variety of tests.
History and physical exam
Your doctor will first ask you about your symptoms, such as when they started.
You may be asked about any other illnesses you have, your travel history, and exposure to certain environmental factors where you live and work.
Because they’re small and usually cause no symptoms, granulomas are often discovered accidentally.
For example, if you’re having a routine chest X-ray or CT scan because of a respiratory problem, your doctor may discover small spots on your lungs that turn out to be granulomas. If they’re calcified, they’re especially easy to see on an X-ray.
At first look, granulomas resemble possibly cancerous tumors. A CT scan can detect smaller nodules and provide a more detailed view.
Cancerous lung nodules tend to be more irregularly shaped and larger than benign granulomas, which generally are
If your doctor sees what appears to be a small and harmless granuloma on an X-ray or CT scan, they may monitor it for a while, taking additional images over a period of years to see if it grows.
To help determine the cause of your lung granuloma, your doctor may order laboratory tests such as the following:
- Complete blood count (CBC). A high number of white blood cells could indicate an infection.
- Serology. This type of blood test finds antibodies in your blood that can indicate a fungal, bacterial, or other type of infection.
- Tuberculosis testing. A purified protein derivative (PPD) skin test can determine if someone may have been exposed to tuberculosis.
Procedures such as the following may be done to examine the lung granuloma:
- Bronchoscopy. After you’re given relaxing medication, a thin tube called a bronchoscope that has a light and camera is inserted through your nose or mouth and down your throat to your lungs.
- Bronchoalveolar lavage. During a bronchoscopy, sterile saline may be injected in your lungs. A sample of cells is then suctioned out and examined under a microscope to detect hypersensitivity pneumonitis.
- Endobronchial ultrasound. During a bronchoscopy, an ultrasound probe attached to the bronchoscope enables your doctor to see areas of your lungs.
Your doctor may also take a biopsy of a lung granuloma to determine if it’s cancerous. A biopsy involves removing a small piece of suspicious tissue with a bronchoscope or a thin needle.
The tissue sample is then examined under a microscope.
Pulmonary function tests (PFTs), breathing tests that measure how efficiently air moves in and out of your lungs, may also be recommended by your doctor.
A larger granuloma may be evaluated over time using lung positron emission tomography (PET) scans. This type of imaging uses the injection of a radioactive substance to identify areas of inflammation or malignancy.
Lung granulomas typically don’t require treatment, especially if you have no symptoms.
Because granulomas are usually the result of a diagnosable condition, treatment of the underlying condition is important.
For example, a bacterial infection in your lungs that triggers granuloma growth should be treated with antibiotics. An inflammatory condition, such as sarcoidosis, may be treated with corticosteroids or other anti-inflammatory medications.
Once you have the underlying cause of lung granulomas under control, you may not have additional nodules form in your lungs.
Some conditions, such as sarcoidosis, have no cure, but can be fairly well managed. While you may keep inflammation levels down, it’s possible more granulomas may form.
Lung granulomas and other growths in your lungs are usually identified when your doctor is looking for other respiratory problems. That means it’s important to report symptoms such as coughing, shortness of breath, and chest pain promptly to your doctor.
The sooner you have symptoms evaluated and diagnosed, the sooner you can get helpful treatment.