What Is Sarcoidosis?

It often starts with a scan you had for some other reason. A chest X-ray taken before an operation, or after a stubborn cough, comes back showing swollen lymph nodes in the middle of the chest — and a word you've probably never heard: sarcoidosis. So what should you expect from there? Sarcoidosis is an inflammatory illness in which tiny clusters of immune cells, called granulomas, form in organs — most often the lungs and the lymph nodes inside the chest, though the skin, eyes, and other organs can be involved too. The short explainer at the top of this page, about four minutes long, describes what sarcoidosis is; this guide walks through what usually happens next, step by step.

Expect the first clue to be a picture, not a feeling

Plenty of people with sarcoidosis feel completely well when it's found. Others notice a dry cough that won't settle, breathlessness on hills or stairs, tiredness that feels out of proportion, tender red lumps on the shins, sore or light-sensitive eyes, or a rash. Because those symptoms overlap with far more common problems — a lingering chest infection, for instance, as our guide to pneumonia covers — the scan is usually what points the way. The second video on this page, about three minutes long, walks through exactly that picture: how sarcoidosis shows up on a chest X-ray, typically as enlarged lymph nodes on both sides of the chest alongside changes in the lung tissue itself.

Expect more tests before anyone names it

A suggestive X-ray is a starting point, not a diagnosis. You'll usually have a CT scan for a closer look at the nodes and lungs, breathing tests to measure how well your lungs are working, and blood tests — which also check calcium, since sarcoidosis can push calcium levels up. Because the eyes can be affected without symptoms, an eye examination is a routine part of the work-up as well. And because other illnesses can look similar on a scan, your team will be thinking about alternatives at the same time, including infections such as tuberculosis and other lung conditions covered in our overview of COPD.

Expect a biopsy — it's how the diagnosis is confirmed

The confirming step is a tissue sample showing granulomas, with other causes for them ruled out. These days that sample often comes from the swollen chest lymph nodes themselves, taken during a bronchoscopy — a camera examination of the airways described in our guide to bronchoscopy — using an ultrasound-guided needle passed through the airway wall. Sometimes a skin lump or another accessible site offers an easier target. It isn't the granuloma alone that makes the diagnosis; it's the combination of your scans, your symptoms, the biopsy, and the absence of another explanation, all fitting together.

Expect that treatment might simply be watching

Here's the part that surprises many people: sarcoidosis frequently settles on its own, so if your symptoms are mild and your organs are working well, the plan may be monitoring alone — regular scans, breathing tests, and blood checks to confirm things are stable or improving. Treatment steps in when symptoms are troublesome, when lung function is slipping, or when a sensitive organ such as the eyes, heart, or nervous system is involved. When it does, corticosteroid tablets are usually the first approach, with other immune-suppressing medicines considered if steroids aren't enough, aren't tolerated, or are needed for a long time. Which path is right for you — and whether you need treatment at all — is a judgment your specialist makes from the whole picture, not from any single test.

Expect follow-up to run for a while

Even when sarcoidosis quiets down, follow-up usually continues, because the illness can flare again after a quiet period and because a minority of people develop lasting scarring in the lungs that needs ongoing care. Expect periodic breathing tests and imaging, eye checks, and blood tests including calcium. Tell your team about new breathlessness, palpitations, eye symptoms, or a cough that's changing rather than waiting for the next appointment — and keep up with routine care in the meantime. For most people, the long view is reassuring: the condition either fades or stays controlled, and the follow-up exists to catch the exceptions early.

References & further reading

• MedlinePlus — Sarcoidosis: https://medlineplus.gov/sarcoidosis.html
• National Heart, Lung, and Blood Institute (NHLBI) — Sarcoidosis: https://www.nhlbi.nih.gov/health/sarcoidosis
• MedlinePlus Medical Encyclopedia — Sarcoidosis: https://medlineplus.gov/ency/article/000076.htm

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist.

Frequently Asked Questions

What exactly is a granuloma?

A granuloma is a small, organised cluster of immune cells that forms when the immune system tries to wall something off. In sarcoidosis, these clusters appear in organs — most often the lungs and chest lymph nodes — even though no infection or foreign material is found to explain them.

What causes sarcoidosis?

The cause isn't known. The current understanding is that in people with a genetic tendency, something in the environment triggers an exaggerated immune response that produces granulomas. It is not contagious, and you cannot catch it from someone who has it.

Does sarcoidosis always need treatment?

No. It often improves on its own, so many people are simply monitored with scans, breathing tests, and blood tests. Treatment is started when symptoms are significant, lung function is falling, or a vulnerable organ such as the eyes or heart is involved.

Can sarcoidosis come back after it settles?

Yes, it can flare again after a quiet period, which is why follow-up continues even when you feel well. Most recurrences are picked up on routine monitoring or from new symptoms reported early.

Is sarcoidosis a form of cancer?

No. It is an inflammatory condition, not a cancer, and it does not turn into cancer. It can sometimes be mistaken for cancer or infection on scans at first, which is one reason a biopsy is used to confirm the diagnosis.

This article is for general education only and is not medical advice. It does not replace consultation with a qualified clinician. New or worsening breathlessness, chest pain, palpitations, or eye pain or vision changes should be assessed promptly.

Dr. Mohamed Ibrahim, MD, PhD

Physician-scientist · Founder, MedicalVideos.com

Dr. Ibrahim founded MedicalVideos.com in 2007 to make medical and surgical education freely accessible to students, clinicians, and patients.

Last reviewed: 11/08/26