Sarcoidosis – also called sarcoid – is a condition where cells in your body clump together to make small lumps called granulomas.

These granulomas can develop in any part of your body. They are most commonly found in the lungs and the lymph glands which drain the lungs. They can also affect your skin, heart, nervous system, liver, spleen, muscles, nose, sinuses and eyes.

When lots of granulomas develop in one area, they begin to affect how well that part of your body works. This causes symptoms.

What are the effects of sarcoidosis?

Sarcoidosis affects people in lots of different ways. It can cause symptoms in just one part of your body or many parts at the same time. Though sarcoidosis isn’t always a lung condition, the lungs are affected in about 90% of cases. When the lungs are affected, it’s called pulmonary sarcoidosis.

Who gets sarcoidosis?

You can get sarcoidosis at any age, but it commonly affects adults in their 30s or 40s. It’s unusual for children to get sarcoidosis. The NHS estimates that sarcoidosis affects around one person in every 10,000 in the UK.

Causes

We don’t know what causes sarcoidosis, but we do know it’s related to your immune system behaving in a way it shouldn’t.

Normally your immune system fights infections by releasing white blood cells into your blood to destroy germs. This causes the affected part of your body to become inflamed, making it swollen or red.

Researchers think that sarcoidosis could be caused by something in the environment that stops your immune system working properly. Instead of attacking germs, it attacks healthy parts of your body.

Research also suggests that, for some people, the risk of getting sarcoidosis is related to their genes. Sometimes, more than one family member can get sarcoidosis. But there’s no evidence that it’s infectious.

Symptoms

Your symptoms depend on what part of your body is affected. They can include:

  • feeling short of breath
  • a cough which is often dry
  • tiredness and feeling ill
  • red or sore eyes
  • painful red lumps on your shins
  • swollen glands in your face, neck, armpits or groin
  • rashes – usually on your upper body
  • painful joints, bones and muscles
  • an abnormal heart rhythm
  • sweats

Acute sarcoidosis

In some cases, symptoms come on suddenly, but don’t last very long. This is called acute sarcoidosis. Common symptoms of acute sarcoidosis are swollen glands, fever, tiredness, joint pains and lumps or rashes on the legs.

Chronic sarcoidosis

If your symptoms develop gradually and last longer, this is called chronic sarcoidosis. This means that the condition is long term. People with long-term sarcoidosis often have fewer symptoms, but the symptoms can get worse over time.

Are there always symptoms?

Some people don’t experience any symptoms. In this case, you may only discover you have sarcoidosis if you have a chest X-ray for another reason.

Diagnosis

Sarcoidosis can be difficult to diagnose.

It shares symptoms with lots of other diseases and you may not even have any obvious symptoms. This means it can take a while to get a diagnosis.

You might need to have a few different tests, depending on which parts of your body are affected.

Pulmonary sarcoidosis

If it looks like sarcoidosis is affecting your lungs, you’ll probably have a chest X–ray or CT scan. A CT scan uses a special X-ray machine to produce a detailed image of the inside of your body. In most cases, this is enough to find out if you have sarcoidosis.

In some cases, the doctor may want to examine the inside of your lungs more closely by doing a bronchoscopy. This is done using a bronchoscope – a thin, flexible tube with a light and a very small camera at one end. The tube is passed through your nose or mouth, down your windpipe and into your lungs.

The procedure isn’t painful, but it can cause coughing. It’s often done under sedation with a local anaesthetic. Your doctor will be able to give you more details when they discuss the test with you.

During the procedure, your doctor may take a sample of tissue from your lungs. This can be examined under a microscope to see if there are any granulomas. This is called a biopsy.

Some centres prefer to do this using an EBUS-TBNA procedure. The doctor uses a special kind of bronchoscope with ultrasound to see inside your lungs and take a tissue sample. This procedure takes slightly longer than a standard bronchoscopy. But in centres which perform the test regularly, it’s more likely to give a clear diagnosis than a standard bronchoscopy.

Sarcoidosis in other parts of your body

You may have blood tests, urine tests or a biopsy of the affected area. You may also have an electrocardiogram, sometimes called an ECG, which is a simple test that records the rhythm of your heart.

If you’re diagnosed with sarcoidosis in one part of your body, other parts of your body may also be affected. Further tests will help to show how different parts of your body are affected.