Sarcoidosis usually develops in people aged 20 to 40, most often people of European ancestry and American blacks.
It can affect many organs, most commonly the lungs.
People typically cough and have difficulty breathing but can have various symptoms, depending on which organs are affected.
Diagnosis usually requires chest x-ray, usually computed tomography, and analysis of a sample of tissue (biopsy), usually from the lungs.
Symptoms eventually subside without treatment in most people.
Treatment, when necessary, begins with corticosteroids.
The cause of sarcoidosis is unknown. It may result from an infection or from an abnormal response of the immune system to a substance encountered in the environment, such as mold or mildew. Inherited factors seem to be important. Sarcoidosis typically develops between the ages of 20 and 40. It is most common among people of European ancestry and American blacks, although it can occur in anyone.
Sarcoidosis is characterized by the presence of collections of inflammatory cells (granulomas). The disease is primarily one of the lungs and lymph nodes, but granulomas can also form in any organ, including the liver, eyes, and skin, and less often the spleen, bones, joints, sinuses, skeletal muscles, kidneys, heart, reproductive organs, salivary glands, and nervous system. The granulomas may eventually disappear completely or become scar tissue.
Sarcoidosis may manifest as certain syndromes.
Löfgren syndrome manifests as three specific symptoms: acute inflammation of several joints (arthritis), tender red bumps under the skin (erythema nodosum), and enlargement of the lymph nodes in the area where the lungs are connected to the heart and the windpipe. It often causes fever and malaise, inflammation of the lining of the eye (uveitis), and sometimes inflammation of the parotid glands. It is more common among women of European, particularly Scandinavian, descent.
Löfgren syndrome often resolves on its own. But people may be given nonsteroidal anti-inflammatory drugs to help relieve symptoms and inflammation.
Heerfordt syndrome (also called uveoparotid fever) manifests as swelling of the parotid gland (due to sarcoid infiltration), inflammation of the eye (uveitis), chronic fever, and less often weakness or paralysis of the facial nerve. Heerfordt syndrome can resolve on its own. Treatment is the same as for sarcoidosis and includes nonsteroidal anti-inflammatory drugs, including corticosteroids.
Many people with sarcoidosis have no symptoms, and the disorder is discovered on a chest x-ray that is taken for other reasons. Most people develop minor symptoms that do not progress.
The symptoms of sarcoidosis vary greatly according to the site and extent of the disease as well as by the age and sex of the person affected.
Fever, fatigue, vague chest pain, a feeling of illness (malaise), loss of appetite, weight loss, and aching joints may be the first indications of a problem in about one third of people. Enlarged lymph nodes are common but do not often cause symptoms. Fever and night sweats may recur throughout the illness.
The organs most affected by sarcoidosis are the lungs. Enlarged lymph nodes at the place where the lungs meet the heart or to the right of the windpipe (trachea) may be seen on a chest x-ray. Sarcoidosis causes inflammation in the lungs that may eventually lead to scarring and the formation of cysts. Fortunately, such progressive scarring occurs infrequently. Occasionally, the fungus Aspergillus can settle in (colonize) the lung cysts, grow, and cause bleeding. Breathing can become difficult. Severe involvement of the lung by sarcoidosis can eventually strain the right side of the heart, causing right-sided heart failure (cor pulmonale).
The skin is frequently affected by sarcoidosis. Sarcoidosis often starts as a rash with raised, tender, red lumps, usually on the shins (erythema nodosum), often accompanied by a fever and joint pain. The rash tends to resolve within 3 to 6 months but may recur. It is less common in American blacks. Common skin lesions in sarcoidosis include little bumps (called papules) and larger bumps (called nodules). Prolonged sarcoidosis may lead to the formation of flat patches, raised patches (plaques), or plaques that discolor the nose, cheeks, lips, and ears (lupus pernio). Skin patches may be darker or lighter than surrounding skin. Lupus pernio is most common in black Americans and people of Puerto Rican descent. People with lupus pernio may also develop granulomas in the nasal passage that cause symptoms similar to those of sinusitis.
Up to 75% of people with sarcoidosis have granulomas in their liver. These granulomas often cause no symptoms, and the liver seems to function normally. However, blood tests may show evidence of liver involvement even when symptoms of it are absent. Fewer than 10% of people with sarcoidosis have an enlarged liver. Yellow coloring of the skin and whites of the eyes (jaundice) caused by liver malfunction is rare.
The spleen also is enlarged in some people. When the spleen is enlarged, people may have pain in the upper part of the abdomen.
The eyes are affected in 25% of people with sarcoidosis, particularly black Americans and people of Japanese descent. Uveitis makes the eyes red and painful and interferes with vision. Inflammation that persists for a long time may block fluid from draining from the eye, causing glaucoma, which can lead to blindness. Granulomas may form in the membrane over the eyeball and inside the eyelids (conjunctiva). Such granulomas often do not cause symptoms, but the conjunctiva is an accessible site from which doctors can take tissue samples for examination. Some people with sarcoidosis complain of dry, sore, and red eyes, probably because tear glands that have been affected by the disorder no longer produce enough tears to keep the eyes lubricated.
Granulomas that form in the heart may cause palpitations, dizziness, or heart failure. Failure of the right side of the heart (called cor pulmonale) can also develop if the lungs are severely affected by sarcoidosis, causing high pressures in the artery carrying blood from the heart to the lungs (pulmonary hypertension). Granulomas that form near the heart’s electrical conducting system can trigger potentially fatal irregularities in the heartbeat.
Sarcoidosis can affect the cranial nerves (nerves of the head), causing double vision, hearing loss, or making one side of the face droop. If the pituitary gland or the bones surrounding it are affected, central diabetes insipidus may result. In diabetes insipidus, the pituitary gland stops producing vasopressin, a hormone needed by the kidneys to concentrate urine, causing excessive production of urine.
Sarcoidosis can increase the levels of calcium in the blood and urine. High levels occur because sarcoid granulomas produce activated vitamin D, which enhances calcium absorption from the intestine. High blood calcium levels lead to a loss of appetite, nausea, vomiting, thirst, and excessive urine production. If present for a long time, high blood calcium levels may lead to the formation of kidney stones or calcium deposits in the kidney and, eventually, to chronic kidney disease.
Doctors most often suspect sarcoidosis when they observe its distinctive changes, including enlarged lymph nodes and abnormal findings on a chest x-ray or on computed tomography (CT).
Further testing is necessary, typically microscopic examination of a tissue sample (biopsy) showing inflammation and granulomas, to confirm the diagnosis. Bronchoscopy with ultrasound-guided needle biopsy is 90% accurate and is the preferred procedure for people whose lungs are involved. Other possible sources of tissue specimens are skin abnormalities, enlarged lymph nodes close to the skin, and granulomas on the conjunctiva. A liver biopsy is generally not done because liver granulomas can be caused by other disorders and so the biopsy may not provide a definite diagnosis. Cardiac magnetic resonance imaging (MRI), brain or spine MRI, bone scans, and electromyography may be done in people with symptoms related to those organ systems.
Tuberculosis can cause many changes similar to those caused by sarcoidosis. Therefore, doctors also do a tuberculin skin test (and sometimes a lung biopsy) to help determine whether the problem is tuberculosis or sarcoidosis.
Other methods that can help doctors diagnose sarcoidosis or assess its severity include irrigating the lungs (bronchoalveolar lavage) and examining the fluid. The fluid from a lung with active sarcoidosis contains a large number of lymphocytes, but this finding is not unique to sarcoidosis. Another test that is occasionally used is positron emission tomography (PET) scanning, which can detect even small areas of sarcoidosis that affects parts of the body other than the lungs.
In people with lung scarring, pulmonary function tests may show that the amount of air the lungs can hold is below normal. A 6-minute walk test may be done to help determine how severely the lungs are affected. Blood tests may reveal a low number of white blood cells, red blood cells, or, rarely, platelets. Immunoglobulin levels are often high, especially in blacks. Levels of calcium in the blood or urine may be high. The levels of liver enzymes, particularly alkaline phosphatase, may be high if the liver is affected.
Sarcoidosis improves or clears up spontaneously in nearly two thirds of people with lung sarcoidosis. Even enlarged lymph nodes in the chest and extensive lung inflammation may disappear in a few months or years. However, the course can be chronic or progressive in up to 30% of people. Serious involvement outside of the chest (for example, of the heart, nervous system, eyes, or liver) occurs in 4 to 7% of people at the beginning of their illness.
People with enlarged lymph nodes in the chest but no sign of lung disease have a very good prognosis. People with Löfgren syndrome often have the best prognosis. About 50% of people who once had sarcoidosis have relapses.
About 10 to 20% of people with sarcoidosis develop a serious disability due to damage to the eyes, respiratory system, or elsewhere. Sarcoidosis is fatal in 1 to 5% of affected people. Lung scarring leading to respiratory failure and cor pulmonale is the most common cause of death, followed by bleeding due to lung infection caused by Aspergillus.
Most people with sarcoidosis do not need treatment.
People may be given nonsteroidal anti-inflammatory drugs to relieve symptoms such as pain or fever.
Corticosteroids are given to suppress sarcoidosis that causes symptoms such as shortness of breath, joint or chest pain, and fever. These drugs also are given if
Corticosteroids tend to temporarily slow tissue damage caused by sarcoidosis and control symptoms well, but they may not prevent lung scarring over the years. Corticosteroids also may help people with high levels of calcium in the blood or urine. About 10% of people who need treatment do not respond to corticosteroids alone, and they are also given methotrexate, which may be effective.
Sometimes other drugs that suppress the immune system are given if corticosteroids are ineffective or cause troublesome side effects. These drugs may include methotrexate, azathioprine, mycophenolate mofetil, cyclophosphamide, hydroxychloroquine, leflunomide, and infliximab.
Hydroxychloroquine is sometimes helpful in treating disfiguring skin lesions, high blood calcium levels, and some enlarged, uncomfortable or disfiguring lymph nodes.
Some people, especially those who have lupus pernio or involvement of the nervous system, are treated with infliximab. For people who were treated successfully with infliximab but can no longer take infliximab because of its side effects, doctors can give adalimumab.
If the heart is involved, people may need an implantable cardiac defibrillator and a pacemaker.
Sometimes, transplantation of lungs, heart, or liver is done if sarcoidosis has severely affected these organs, but sarcoidosis can recur in the transplanted organ.
The success of treatment can be monitored with chest x-rays, CT, pulmonary function tests, and measurements of calcium in the blood. These tests are repeated regularly to detect relapses after treatment stops.
Moderate or severe lung damage increases the risk of death in people who have sarcoidosis and COVID-19. Doctors must sometimes withhold drugs that suppress the immune system in these people.