It has an active and a non-active phase:
During the active phase, the granuloms form and grow. In this phase, symptoms can develop, and scar tissue can form in the organs where the granulomas occur. In the non-active phase, the inflammation goes down, and the granulomas stay the same size or shrink. But the scars may remain and cause symptoms.
Although anyone can develop sarcoidosis, the disease mainly affects adults between the ages of 20 and 40. The prevalence of sarcoidosis in the US adult population ranges from 1 case to 40 cases per 100,000 people population, with an annual age incidence rate of 10.9 per 100,000 for Caucasians and 35.5 per 100,000 for African Americans. No clear sex predominance exists in this disorder.
Signs and symptoms of sarcoidosis
Sarcoidosis sometimes develops gradually and produces signs and symptoms that last for years, but it can also appear suddenly and disappear just as quickly. Research has shown that there is no rule about the signs and symptoms because they can vary, depending on which organs are affected and how long the patient had the disease.
The most common symptoms involve the lungs, skin, eyes and liver.
It is estimated that the lungs are affected in about 88% of people who have sarcoidosis. The most common symptoms are cough or chest pain. Some people have breathing problems, but most people don’t.
Very often people with sarcoidosis have some skin symptoms and they mostly include rashes or nodules (small bumps on the skin). They can be located all over the face, arms or buttocks, and are more common in African Americans.
It is proven that about 25% of people who have sarcoidosis have eye symptoms. Although these symptoms may affect the vision, they rarely cause blindness. Eye symptoms usually include dry eyes, but they can also include swelling of the tear gland which makes the eyes water.
Sarcoidosis affects the liver in approximately 20% of people who have the disease. The most common symptom is hepatomegalia - the liver enlargement.
The most common cardiac abnormalities include conduction abnormalities and dysrhythmias due to granulomatous infiltration of the heart. Half of the patients with cardiac sarcoidosis have electrocardiography abnormalities of rhythm, conduction, and repolarization.
Other signs and symptoms of sarcoidosis include:
- A vague feeling of discomfort and fatigue
- Weight loss
- Red, watery eyes
- Arthritis in your ankles, elbows, wrists and hands, commonly associated with bumps on the skin over your shins
Possible causes of sarcoidosis
Although many experts are speculating about the possible causes of sarcoidosis, no one really knows the exact cause of the condition. The most common theory is that it may occur when someone’s immune system overreacts to some unknown toxin, drug or pathogen that enters the body through the airways and lungs. Some experts are saying that this could be caused by some kind of bacteria, especially some non-tuberculosis mycobacterium, a member of the family of bacteria that cause tuberculosis. It is also important to point out that only in a small portion of people sarcoidosis may have a genetic component so heredity could play a role.
What is the purpose of the immune system? The immune system helps protect the body from foreign substances and invading microorganisms such as bacteria and viruses, but in sarcoidosis, T-helper lymphocytes seem to respond too strongly to a perceived threat. This means that the immune response is making more damage than the microorganism it self. This triggers the small areas of inflammation called granulomas.
Pathogenesis of sarcoidosis
We have came to the conclusion that sarcoidosis is a chronic inflammatory disease characterized by a highly focused exaggerated immune response to an unknown antigen at the target organs. The most common histological signs of the disease, sarcoid granulomas, are most likely formed in response to a persistent, poorly degradable, antigenic stimulus.
As a result of these various immunologic interactions, a specific cascade of inflammation occurs which is characterized by changes in tissue permeability, cellular influx, and local cell proliferation, resulting in a granuloma.
Diagnosis of sarcoidosis
To find out if a patient has sarcoidosis, most doctors will perform a physical exam looking for the common signs.
No definitive laboratory test diagnostic of sarcoidosis exists. In the absence of a known etiologic agent, sarcoidosis often remains a diagnosis of exclusion. Doctors usually order a blood test to determine the level of a certain chemical called angiotensin-converting enzyme, in the patient’s blood. ACE is produced by the epithelioid cells of granulomas and, thus, may be elevated in the serum of sarcoid patients. When the doctor finds out the level of angiotensin-converting enzyme, it can help him follow the course of the disease and check the response to treatment.
The most effective non-invasive test to support the diagnosis of sarcoidosis is a chest x-ray which typically shows bilateral lymph node enlargement. It is also very helpful if doctors want to exclude other diseases, including tuberculosis, histoplasmosis or other fungal infection, or lymphoma that can also demonstrate lymph node enlargement similar to sarcoidosis.
High-resolution CT imaging is also considered a very helpful and effective diagnostic tool. Characteristic HRCT scan findings include smooth or nodular interstitial thickening of the structures such as bronchi and the surrounding blood vessels.
Pulmonary function tests
These tests measure how much air the lungs can hold and the flow of the air in and out of the lungs. They can also measure the amount of gases exchanged across the membrane between the lung wall and capillary membrane.
Tissue biopsy findings that confirm the diagnosis of childhood sarcoidosis have been documented in many cases. Biopsy is obtained from the most readily accessible organ with the least invasive method.
The diagnosis of sarcoidosis is confirmed by demonstrating a typical granuloma on a biopsy specimen using the microscope. An experienced pathologist must review characteristic pathological changes.
Stages of sarcoidosis
- Stage 0 - Normal findings on chest radiograph
- Stage I - Bilateral hilar lymphadenopathy, which may be accompanied by adenopathy
- Stage II - Bilateral hilar adenopathy with pulmonary infiltrates
- Stage III - Infiltrates in the parenchyma without hilar adenopathy
- Stage IV - Advanced fibrosis with evidence of honey-combing, hilar retraction, bullas, cysts, and emphysema
Risk factors for developing sarcoidosis
Although literally anyone can develop sarcoidosis, there are some factors which can make a person more likely to get this disease:
African Americans are far more likely to develop sarcoidosis than are Caucasians.
The real cause of this still remains unknown. Although sarcoidosis affects Caucasian men and women almost equally, African Americans women get the disease twice as often as African Americans do.
People of Scandinavian, German or Irish descent have an increased risk.
Sarcoidosis normally occurs between the ages of 20 and 40. It rarely affects children, but can occur in adults older than 50.
What are the most important goals of therapy? The goals of the treatment are to:
- Improve how the organs affected by sarcoidosis work
- Relieve the symptoms
- Shrink the granulomas
The main treatment for sarcoidosis is a corticosteroid medication called Prednisone®.
Prednisone® is very strong anti-inflammatory drug. It almost always relieves symptoms of the inflammation. Prednisone is usually given for many months, sometimes for a year or more.
Low doses of Prednisone® can often relieve symptoms without causing major side effects.
There are also some other medications, mostly immune system suppressants, which may prevent the immune system from fighting things like bacteria and viruses.
The most commonly used are:
- Hydroxychloroquine (Plaquenil®, Quineprox®)
- Methotrexate (Rheumatrex®, Trexall®)
- Azathioprine (Imuran®)
- Cyclophosphamide (Neosar, Revimmune, Cytoxan®)
Disciplined avoidance of sunlight and Vitamin D foods is necessary in patients who are prone to develop hypercalcemia, and will help relieve symptoms in all sarcoidosis patients.
Antibiotic therapy has been reported to be effective for lung, lymph and cutaneous manifestations of sarcoidosis.