Sarcoidosis explained: symptoms, diagnosis and treatment

What sarcoidosis is

Sarcoidosis is a condition in which the immune system, which normally fights infection, becomes overactive and forms tiny lumps of inflammatory cells called granulomas. These clumps can build up in one or several organs and interfere with how they work. The lungs and the lymph glands in the chest are affected most often, but sarcoidosis can involve the skin, eyes, joints, liver, heart, nerves and other parts of the body. Exactly why it happens is not fully understood; it is thought to involve the immune system reacting to something in a person who is susceptible, but it is not an infection and it is not contagious or a cancer. It is not usually inherited in a simple way, though it can occasionally run in families.

The symptoms it causes

Because sarcoidosis can affect so many organs, its symptoms vary enormously. Many people have general symptoms such as tiredness, a mild fever, aching joints, night sweats and weight loss. When the lungs are involved, there may be a persistent dry cough, breathlessness and chest discomfort. Skin sarcoidosis can cause rashes or tender red lumps, often on the shins. Eye involvement can cause redness, pain, blurred vision or light sensitivity. Some people notice swollen glands. A well-known pattern, more common in some people, combines tender shin lumps, swollen ankles, fever and swollen chest glands, and often settles by itself. Less commonly, the heart or nervous system is affected, which can be more serious. Some people, though, have no symptoms at all and are found by chance.

How it is diagnosed

Diagnosing sarcoidosis can take time because it mimics other conditions. It is often suspected from the symptoms together with a chest X-ray or scan showing swollen glands or changes in the lungs. Blood tests check how organs such as the liver and kidneys are working and look for inflammation and calcium levels. Because other conditions, including infections such as tuberculosis and some cancers, can look similar, doctors usually want to confirm the diagnosis, often by taking a small sample of affected tissue, called a biopsy, to look for the typical granulomas under the microscope. Further tests depend on which organs may be involved: for example, an eye examination, heart tracing or scans, and breathing tests to measure lung function. Building this picture helps confirm sarcoidosis and judge how active it is.

How it is treated

Treatment depends on which organs are affected and how much trouble the condition is causing. In many people, especially with mild disease, sarcoidosis needs no treatment at all and improves on its own over months to a couple of years; the approach is careful monitoring rather than medicines. When treatment is needed — for troublesome symptoms, worsening lung function, or involvement of important organs such as the eyes, heart or nervous system — the mainstay is medicine to calm the overactive immune system and reduce inflammation. If longer-term treatment is required, other immune-suppressing medicines may be added. Treatment is tailored to the individual and reviewed over time, and specialists in the lung, eye, heart or other affected areas may be involved. The aim is to control inflammation, protect organ function and manage symptoms with the least medicine necessary.

Living with sarcoidosis

For many people sarcoidosis is a passing illness that settles, but for some it is a long-term condition that needs monitoring over years, because it can flare, change organs or, rarely, cause lasting damage. Regular follow-up allows any new organ involvement to be picked up early. Tiredness is one of the most common and frustrating symptoms, and pacing activities, staying gently active and looking after general health all help. It is important to attend eye checks if advised, since eye involvement can be silent, and to report new symptoms such as chest pain, palpitations, fainting, severe headaches or vision changes, which may signal involvement of the heart, brain or eyes. With good monitoring and treatment when needed, most people with sarcoidosis live well, and support from specialist teams and patient organisations can make a real difference.