Sarcoidosis is a condition where tiny lumps (nodules), known as granulomas, develop at various sites within your body, due to inflammation. It most commonly affects the lungs. However, it can affect almost any part of the body. The exact cause is not known. In many people, sarcoidosis goes away without any treatment. However, in some people, it can become long-standing, and serious, requiring treatment.

Sarcoidosis is a condition where tiny lumps (nodules), known as granulomas, develop at various sites within your body, due to inflammation. These granulomas are made up of cells involved in inflammation. Sarcoidosis most commonly affects the lungs and lymph glands in the chest area (pulmonary sarcoidosis). However, it can affect almost any part of your body, including your eyes, skin, heart, liver, kidneys, salivary glands, muscles, nose, sinuses, brain and nerves. If lots of granulomas form in a part (or organ) of your body, this can start to affect how that part of your body works and functions. So, it is the presence of the granulomas formed in response to inflammation that causes the symptoms of sarcoidosis in the various parts of your body.

The exact cause of sarcoidosis is not known. However, it does seem to run in some families so it is likely that some people have a genetic tendency (susceptibility) to develop sarcoidosis. It has been suggested that something such as an infection or another 'agent' found in the environment may trigger sarcoidosis in someone who is genetically susceptible to it. So far, no definite infection or agent acting as this trigger has been identified.

Sarcoidosis can affect almost any part of your body. It can also affect more than one part of your body at the same time:

• The lungs and the lymph glands in the chest area are most commonly involved in sarcoidosis. They are affected in about 9 in 10 people with sarcoidosis.
• The skin is affected in about 1 in 4 people with sarcoidosis.
• The lymph glands elsewhere in the body are affected in about 1 in 6 people with sarcoidosis.
• The eyes are affected in about 1 in 8 people with sarcoidosis.
• The nerves and nervous system are affected in about 1 in 20 people with sarcoidosis.
• The heart is affected in about 1 in 50 people with sarcoidosis.
• Sarcoidosis can also affect other parts of the body, including bones, joints, muscles, the liver, the spleen, the kidneys, and the gut.

You may not know that you have sarcoidosis. It may be diagnosed when you have a chest X-ray for another reason. Up to half of people with sarcoidosis do not know that they have it. They have no symptoms. The symptoms may come on quite quickly, over a couple of weeks or so. Some doctors call this acute sarcoidosis. Generally, acute sarcoidosis has a good outlook and tends to go away of its own accord without treatment. Löfgren's syndrome is a type of acute sarcoidosis. It is a combination of erythema nodosum (see below) with swollen or enlarged lymph glands seen on your chest X-ray, inflammation in your eye (uveitis) and joint pains. In other people with sarcoidosis, symptoms come on more slowly over a few months or so. Some doctors call this chronic sarcoidosis. Symptoms can become worse over time and often treatment is needed.

Your doctor may ask you a number of questions if they suspect that you have sarcoidosis. This is to look for any symptoms that you may have and to see which parts of your body sarcoidosis could be affecting. Depending on your symptoms, your doctor may also suggest that they examine you. For example, they may suggest that they listen to your chest, carry out an examination of your lymph glands, examine your skin, etc. Your doctor may then suggest some tests. Some of these tests may depend on which part of your body is affected. Tests may include:

• Blood tests - your doctor may suggest some blood tests to look for signs of inflammation. They may check the level of calcium in your blood, as this can be raised in sarcoidosis. They may also check your kidney and liver function and check for a lack of iron in the body (anaemia). Some doctors also suggest a blood test to check the levels of a protein (an enzyme) in your blood, known as angiotensin-converting enzyme (ACE). The levels of this protein are raised in some people with sarcoidosis. However, its usefulness in helping to diagnose sarcoidosis is thought to be limited.
• Chest X-ray - if your doctor suspects that your lungs may be affected by sarcoidosis, they will usually arrange a chest X-ray.
• Spirometry - your doctor may suggest a special test of your lungs, called spirometry. A spirometer is a device which measures the amount of air that you can blow out. See separate leaflet called Spirometry for more details.
• Heart tracing (electrocardiogram, or ECG) - your doctor may arrange an ECG. This records the electrical activity of your heart and shows if there are any problems with this due to sarcoidosis that has affected your heart. See separate leaflet called Electrocardiogram (ECG) for more details.
• Dipstick test of your urine - a special testing strip is dipped into your urine sample to look for any signs of blood vessel or kidney problems due to sarcoidosis.

A biopsy - in order to make a definite diagnosis of sarcoidosis, in most cases, a small sample of tissue (a biopsy) needs to be taken from one of the areas of inflammation (granulomas). If your lungs are a problem, a bronchoscopy is usually done. A small telescope is passed via your nose, down your windpipe (trachea) and into your lungs. A sample of tissue is taken from your lungs and sent to the laboratory. The inflammation of sarcoidosis has a typical appearance when it is examined under a microscope. A biopsy may also be taken from other areas if sarcoidosis is suspected there - for example, your skin, lymph glands, etc.

CT or MRI scans - if your lungs are thought to be affected, a specialist may suggest a CT scan to allow a more detailed look at your lungs. An MRI scan of your heart or your brain may be suggested if sarcoidosis is thought to be affecting your heart or your nervous system.

Echocardiogram - you may be referred for an ultrasound scan of your heart (an echocardiogram). This can show if your heart is enlarged or affected by sarcoidosis. Other investigations to look at your heart may also be suggested.

More detailed lung function tests - other tests to look at how your lungs are working may be suggested. Lung function tests may also be used to look to see if your sarcoidosis is worsening or if it is responding to treatment.

Tests to look for eye involvement - you may be referred for a detailed examination of your eyes by an eye specialist, even if you do not have any specific eye symptoms. This is because sarcoidosis involving the eyes can seriously affect your vision if it is not treated quickly. The examination will usually involve the specialist using a special microscope (a slit lamp) to examine your eyes.

More than three quarters of people with sarcoidosis do not need any treatment because their symptoms are not severe. However, sometimes simple painkillers such as paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may help to ease symptoms. For example, they may help to ease pain from the rounded lumps (nodules) of erythema nodosum, or joint pains. If treatment is needed for sarcoidosis, the aim of treatment is to reduce the inflammation and therefore the symptoms that it causes. The main treatment for sarcoidosis is usually with steroid tablets. The steroids help to reduce inflammation. Prednisolone is usually used and generally needs to be taken daily at first. Treatment with steroid tablets is often needed for at least 6-24 months. Over this time, the dose of the steroid may be gradually reduced. You are more likely to need treatment with steroid tablets if sarcoidosis is affecting your nervous system, heart or eyes, or if you have high calcium levels in your blood, or severe breathing/lung symptoms. Steroid drops or ointments are sometimes used for sarcoidosis affecting the eyes. If sarcoidosis affects your lungs then you should have an influenza immunisation each year.

As many as 2 in 3 people with sarcoidosis do not need any specific treatment. Their sarcoidosis will get better of its own accord over the following two to five years. In about 1 in 3 people with sarcoidosis, it becomes persistent (chronic) and may require treatment. Someone with sarcoidosis can (rarely) be severely affected and may die. This is usually due to severe involvement of the lungs, leading to respiratory failure. The outlook tends to be not so good if sarcoidosis affects areas of your body outside your lungs, particularly if it affects your heart or your nerves. People who develop sarcoidosis quickly, over a few weeks, tend to have a better outlook. So do those who develop erythema nodosum, or those who just have swollen lymph glands seen on their chest X-ray and no real breathing or chest symptoms.