Sarcoidosis (Boeck's disease):
when nodules form in the lungs and other organs

1. What is sarcoidosis?

In sarcoidosis, also known as Boeck's disease, the immune system forms tiny inflammatory nodules in various places in the body, known as granulomas. They consist of immune cells that cluster together as if they had to wall off a foreign body — except that no pathogen or foreign body is found.^¹,²

In the vast majority of those affected, the lungs and the lymph nodes in the chest are involved. But the nodules can also affect the skin, eyes, heart, nervous system, liver, kidneys and joints — which is why it is called a multisystem disease. Two things up front: sarcoidosis is not contagious and not cancer. And in many people it resolves without treatment.^¹

The course varies widely: from an incidental finding on an X-ray that never causes symptoms to a chronic illness that permanently threatens the lungs, heart or eyes. It is precisely this range that makes the question “treat or wait?” so important.

2. Types and stages

• Acute sarcoidosis (Löfgren's syndrome) — begins suddenly with fever, painfully swollen ankles, reddish-blue, tender lumps on the shins (erythema nodosum) and enlarged lymph nodes at the roots of both lungs. Despite the dramatic onset, the outlook is usually good.
• Chronic sarcoidosis — begins gradually, often with a cough, breathlessness on exertion or exhaustion, or is discovered by chance. It can persist for years.
• Organ involvement outside the lungs — the heart, eyes and nervous system are particularly important, because lasting damage is possible here.

For the lungs, the classification based on the X-ray (according to Scadding) is traditionally used:^²

Important: the stages describe the X-ray, not an inevitable progression. Nobody automatically “slides” from stage I to stage IV.

3. Symptoms: from unnoticed to organ involvement

Some of those affected have no symptoms at all. If they do, the symptoms depend on which organs are involved:^²

• Lungs — a dry cough, shortness of breath on exertion, a feeling of pressure in the chest.
• General — marked tiredness, fever, night sweats, weight loss.
• Skin and joints — erythema nodosum, bluish-red skin changes, joint pain.
• Eyes — inflammation of the iris and surrounding structures (uveitis) with redness, pain, sensitivity to light and blurred vision — sometimes with no symptoms at all.
• Heart — palpitations, a racing heart, dizziness or fainting due to rhythm disturbances.
• Nervous system — for example facial palsy, headaches, burning nerve pain.

4. Causes: what is known — and what is not

The cause has still not been clarified. According to current knowledge, a trigger from the environment meets a hereditary predisposition, and the immune system overreacts:^¹,²

• Predisposition — clusters in families and certain gene variants of the immune system increase the risk.
• Inhaled particles — dusts, metals, mould or smoke are discussed as triggers; certain occupations appear to be affected more often. Your occupational history is therefore part of the diagnosis.
• Pathogens as triggers — components of certain bacteria are suspected of setting off the reaction. This has not been proven, and sarcoidosis is not contagious.

5. Diagnosis: ruling things out and checking the organs

Sarcoidosis is a diagnosis of exclusion. According to the guideline of the American Thoracic Society (ATS), three pillars are needed: a compatible clinical picture, evidence of typical granulomas in a tissue sample, and the exclusion of other causes such as tuberculosis, lymphoma or fungal infections. In typical Löfgren's syndrome, a tissue sample can be dispensed with.^³

• Imaging: an X-ray and usually computed tomography (CT) of the chest.
• Lung function: including the diffusing capacity, which shows how well oxygen passes into the blood — important as a baseline.
• Bronchoscopy: examination of the airways with lavage and a tissue sample, often taken from the lymph nodes under ultrasound guidance.
• Blood tests: calcium, kidney and liver values, blood count. The frequently measured ACE neither proves nor rules out the disease — a normal value does not exclude sarcoidosis.
• Eye examination: even without symptoms, because uveitis can go unnoticed.
• ECG: to look for heart involvement, supplemented if abnormal by a Holter ECG, echocardiography or cardiac MRI.
• History: occupation, hobbies, dusts — and all medicines, including cancer or rheumatology treatments.

6. Treatment: wait or treat?

The most important message first: not every case of sarcoidosis needs treatment. The guideline of the European Respiratory Society (ERS) and the position paper of the German Respiratory Society (DGP) recommend treatment mainly when an organ is at risk of lasting damage, when there is a danger to life, or when quality of life is significantly impaired.^⁴,⁵

Put honestly: the evidence is thinner than you would expect for a disease that has been known for decades. Many recommendations are conditional and based on low-quality studies. Cortisone often improves symptoms and lung function quickly; whether it changes the long-term course is less clear — and relapses after stopping are not uncommon.^⁴

Special cases are treated separately: with heart involvement, an implanted defibrillator may be needed alongside the immunotherapy; with eye involvement, ophthalmologists often treat with cortisone eye drops. Which treatment suits you is decided by the treating practice — ideally one with experience of sarcoidosis.^⁵

7. Cortisone, methotrexate & co. in everyday life

Cortisone over months

Taken over a long period, cortisone shows its well-known side effects: weight gain, higher blood sugar and blood pressure, sleep problems, mood swings, susceptibility to infection, cataracts and bone loss, up to osteoporosis. Taking it in the morning matches the body's natural rhythm. How to keep an eye on the side effects is explained in the cortisone guide.^⁵

Methotrexate: once a week

• Set a day of the week: in sarcoidosis, methotrexate is taken once a week, not daily. Mix-ups with daily intake have led to life-threatening overdoses.
• Folic acid: usually added, on a different day set by the practice, to reduce side effects.
• Lab checks: blood count, liver and kidney values at fixed intervals.
• Interactions: the antibiotic co-trimoxazole and higher-dose anti-inflammatory painkillers can increase toxicity; alcohol puts an additional strain on the liver.
• Planning a family: methotrexate can seriously harm an unborn child and must be stopped in good time beforehand — plan early with the practice, see Medications during pregnancy.

Immunosuppression and vaccinations

Cortisone, methotrexate and TNF inhibitors weaken the immune defences. Your vaccination status should therefore be checked before starting treatment if possible, for example for flu, pneumococci and shingles with an inactivated vaccine. Live vaccines are generally off limits under stronger immunosuppression — details in the guide Vaccines and medications. Fever while on immunosuppression should be assessed by a doctor promptly.

8. Vitamin D, calcium and sun

One point that is easily overlooked in sarcoidosis: the granulomas can produce active vitamin D themselves. As a result, the gut absorbs more calcium. The consequence can be raised calcium levels in the blood or urine — with thirst, frequent urination, nausea, confusion, kidney stones and, in the worst case, kidney damage.^²,⁵

This does not mean that vitamin D is fundamentally forbidden in sarcoidosis — a genuine deficiency does occur. It just means: not by gut feeling, but according to lab values. More about the substance under Vitamin D and about supplements in the guide Supplements and medications.

9. Exhaustion and long-term effects

Many of those affected report profound exhaustion (fatigue) that can persist even when the X-ray and lung function have long since looked good again. Some also experience burning or tingling pain due to damage to fine nerve fibres, as well as low mood.^⁴

• Check for other causes — cortisone side effects, anaemia, the thyroid, sleep apnoea or depression can make the tiredness worse and are treatable.
• Increase activity gradually — according to the ERS guideline, structured exercise training, for example in pulmonary rehabilitation, can be considered; the evidence is limited, but it generally does no harm.
• Pulmonary fibrosis — in a smaller proportion of people, scarring of the lungs remains. The focus is then on preserving lung function, rehabilitation and, if needed, oxygen.

10. Everyday life with sarcoidosis

• Keep up with check-ups — lung function, eyes, ECG and calcium, even in good phases; relapses do not always announce themselves.
• Protect your lungs — do not smoke, avoid dusts and fumes at work or wear protection.
• Keep dosing rhythms separate — daily cortisone, weekly methotrexate, folic acid on a different day: fixed days of the week and reminders prevent mix-ups.
• Keep your medication plan complete — including vitamin D, calcium and over-the-counter products; instructions under Create a medication plan.
• Plan a pregnancy — sarcoidosis often remains stable during pregnancy but can flare up again after the birth; the medicines must be reviewed beforehand.
• Connect with others — self-help organisations such as the Deutsche Sarkoidose-Vereinigung (German sarcoidosis patient association) offer information and contact with other people affected.

Sarcoidosis is a disease with many different faces. For many it remains an episode; for some it becomes a long-term companion. In both cases: look closely, treat only what needs treating — and then carry out the treatment consistently and safely.

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