What is pulmonary sarcoidosis?
Pulmonary sarcoidosis is an inflammatory condition where abnormal tissue forms in the lungs. Often the lymph nodes within the chest cavity are also affected. This abnormal tissue is known as a granuloma and is the type of tissue that arises when the body tries to wall off an infection. However, in sarcoidosis these granulomas form for some unknown reason.
Sarcoidosis is not a common disease, affecting less than 1% of the American population. It is often misdiagnosed for other lung conditions like tuberculosis and a large number remains asymptomatic due to a lack of symptoms or non-specific symptoms. Many cases of sarcoidosis resolve spontaneously although treatment may be required at times. Death from sarcoidosis is not common but can arise as a result of complications.
What happens in sarcoidosis?
Granulomas are small nodules or lumps that can form anywhere in the body. Most of the time these masses arise from an infection. A granuloma is the body’s way of walling off an infection. This usually happens when the body is unable to destory the invading microbe but has to restrict it to prevent further spread of the infection. The ‘wall’ is formed by a number of different immune cells.
Circulating monocytes, a type of immune cell, aggregates at the affected area. These monocytes can differentiate into another type of immune cell known as macrophages. It surrounds the target area and becomes transformed. These macrophages are known as epithelioid cells. It is in turn surrounded by lymphocytes (white blood cells). Collectively these cells keep the microbes trapped. The surrounded tissue may be destroyed or become calcified (hardened).
However, in sarcoidosis there is no infection that can be identified at the area where a granuloma forms. There is usually no tissue destruction and the granulomas can resolve even without treatment. Despite the lack of an infection there is still inflammation at the affected site. It is not an autoimmune disease as is sometimes incorrectly thought.
Causes of Lung Sarcoidosis
The exact cause of sarcoidosis remains unknown. It appears that certain people are more likely to develop sarcoidosis possibly due to a genetic predisposition. This affects the way the immune system reacts and it can be triggered by viruses or bacteria. However, it is important to note that sarcoidosis is not an infection. Dust and exposure to various chemicals could also serve as a trigger.
Once the immune system is abnormally activated, it causes the formation of granulomas. Even though it arises with a dysfunction in the immune system, sarcoidosis is not an autoimmune disease where the immune system attacks healthy tissue in the body. The nodules (granulomas) should also not be confused with malignant tumors (cancer). Due to the presence and accumulation of these granulomas, it can affect organ function in various ways.
- Read more on neurosarcoidosis.
- Read more on chronic exertional dyspnea.
- Read more on types of lung diseases.
Signs and Symptoms
About 5% of cases present with no symptoms (asymptomatic). These cases are diagnosed incidentally during a chest x-ray o other imaging technique. Another 45% of patients do not experience lung symptoms and may present with fever and loss of appetite which can be vague. The other 50% of sarcoidosis cases present with pulmonary symptoms including:
- Coughing (usually dry and persistent)
- Shortness of breath (usually with exertion)
- Abnormal breathing suonds like wheezing
- Chest pain
- Vomitng up blood (hemoptysis) which is rare
Weight loss, fatigue, night sweats, hoarse voice, swollen lymph nodes, skin nodules, joint pain and eye symptoms may also be present. Disturbances with the heart rate, kidney function, liver function, brain and nerve function, and blood abnormalities may also arise with sarcoidosis.
How serious is sarcoidosis?
The seriousness of sarcoidosis depends on individual cases, early diagnosis and proper treatment.Naturally the severe cases of sarcoidosis are more serious and can lead to significant impairment of lung function which may progress to complications. In these seevere cases, death may also be a possibility as a result of respiratory failure. The heart can also be affected which can lead to fatal outcomes.
However, it is important to note that most cases are not severe and can be effectively treated and managed. Even without treatment some cases may resolve spontaneously and not recur. Even in moderate to severe cases of sarcoidosis, the death rate is less than 5% even without treatment. This should not detract from treating the condition as proper management can play a major role in the quality of life and progression of the disease.
The prognosis for sarcoidosis depends on the stage of the disease. It is divided into four stages with stage I being the mildest and as many as 90% of cases going nto remission. Most of these patients are asymptomatic. Stage IV is the most severe form and remission never occurs. The risk of death in stage IV is significantly high but even in these cases it depends on the quality of care.
Treatment of Sarcoidosis
Most patients require treatment only for the symptoms. However, this depends on the severity of sarcoidosis. In asymptomatic cases it may not be necessary to start with any treatment. Constant monitoring would nevertheless be necessary to assess lung function. In these cases treatment may be commenced once the lung function decreases to a certain level even if symptoms are still absent.
Treatment with Steroids
The main approach to treating sarcoidosis is to use corticosteroids like prednisone. Not only do steroids suppress the abnormal immune activity but it also reduces the inflammation thereby easing symptoms of sarcoidosis. Higher doses of prednisone are used for short periods of time until symptoms improve or resolve. Some patients require long term use of steroids at lower doses.
Other drugs may be used instead of steroids if the condition does not respond to steroids or is experiencing adverse effects from steroid use. Some patients may not want to use steroids and therefore these other drug options needs to be cnsidered. It includes:
- Chloroquine and hydroxychloroquine
- Infliximab and thalidomide
Surgery is rarely needed for sarcoidosis. It involves lung transplantation in patients with severly impaired lung function in advanced sarcoidosis.