Sarcoidosis

Sarcoidosis is a disease that features a specific type of inflammation of various tissues of the body. Sarcoidosis can appear in almost any body organ, but it starts most often in the lungs or lymph nodes. As sarcoidosis progresses, microscopiclumps of a specific form of inflammation, called granulomas, appear in the affected tissues. In the majority of cases, these granulomas clear up, either with or without treatment. In the few cases in which the granulomas do not heal and disappear, the tissues involved tend to remain inflamed and become scarred (fibrotic). In addition to the lungs and lymph nodes, the organs more likely than others to be affected by sarcoidosis are the liver, skin, heart, nervous system, and kidneys, in that order of frequency.

Sarcoidosis is sometimes named according to the organ involved.

• When sarcoidosis affects the lungs, it can be referred to as lung sarcoidosis or pulmonary sarcoidosis.
  
• When sarcoidosis affects the liver, it can be referred to as hepatic sarcoidosis.
  
• When sarcoidosis affects the skin, it can be referred to as skin sarcoidosis or sarcoid dermatitis.
  
• When sarcoidosis affects the heart, it can be referred to as heart sarcoidosis or cardiac sarcoidosis.
  
• When sarcoidosis affects the nervous system including the brain, it can be referred to as neurological sarcoidosis or neurosarcoidosis.
  
• When sarcoidosis affects the kidneys, it can be referred to as kidney sarcoidosis or renal sarcoidosis.

Sarcoidosis Causes

The cause of sarcoidosis is unknown. Sarcoidosis is currently thought to be associated with an abnormal immune response. It is not known whether the triggerthat initiates the immune disturbance is a foreign substance, chemical, drug, virus, or some other substance. Sarcoidosis is not acancer. It is not contagious, and friends and family will not catch it from an affected individual. Although it can occur in families, there is no evidence that sarcoidosis is passed from parents to children.

Sarcoidosis Symptoms

Sarcoidosis can appear suddenly and disappear. Alternatively, it can develop gradually and go on to produce symptoms that come and go, sometimes for a lifetime.

The symptoms of sarcoidosis depend on what areas of the body are affected.

• Shortness of breath (dyspnea) and a coughthat won't go away can be among the first symptoms of sarcoidosis.
  
• But sarcoidosis can also show up suddenly with the appearance of skin rashes.
  
  
  • Tender, raised, red bumps (called subcutaneous sarcoidosis or erythema nodosum) on the shins of the legs, or less frequently on the arms, are common and can cause leg or arm pain.
    
  • A rash on the surface of the skin (cutaneous sarcoidosis or sarcoid dermatitis) of the face occurs frequently.
    
• Inflammation of the eyes can also occur.

More generalized symptoms of sarcoidosis include:

• weight loss,
  
• fatigue,
  
• night sweats,
  
• fever, or
  
• just an overall feeling of ill health.

It is important to note that sarcoidosis is usually not crippling. It often goes away by itself, often healing in 24 to 36 months. Even when sarcoidosis lasts longer, most patients can go about their lives as usual

When to Seek Medical Care

Anyone with the symptoms of shortness of breath and persistent cough should have an evaluation by a health care professional. Furthermore, those with a persistent rash, weight loss, fatigue, night sweats, and/or fever should have a medical examination. Moreover, patients with a known diagnosis of sarcoidosis should have medical follow-up.

Exams and Tests

The preliminary diagnosis of sarcoidosis is based on the patient's medical history, routine tests, a physical examination, and a chest X-ray. The doctor confirms the diagnosis of sarcoidosis by eliminating other diseases with similar features.

These include such granulomatous diseases:

• as berylliosis (a disease resulting from exposure to beryllium metal),
  
• tuberculosis, farmer's lung disease (hypersensitivity pneumonitis),
  
• fungal infections,
  
• rheumatoid arthritis,
  
• rheumatic fever, and
  
• cancer of the lymph nodes (lymphoma).

No single test can be relied on for a correct diagnosis of sarcoidosis. X-rays and blood tests are usually the first procedures the doctor will order. Pulmonary function tests often provide clues to diagnosis. Other tests may also be used, some more often than others.

The biopsy of a tissue sample of an involved organ is the ultimate test to confirm the diagnosis. Many of the tests that the doctor uses to help diagnose sarcoidosis can also help the doctor follow the progress of the disease, and determine whether the sarcoidosis is getting better or worse. The following are commonly used tests in the evaluation of a patient with sarcoidosis.

Chest X-ray

The chest X-ray is often helpful to give the doctor a picture of the lungs, heart, as well as the surrounding tissues containing lymph nodes (where infection-fighting white blood cells form) and give the first indication of sarcoidosis. For example, a swelling of the lymph glands between the lungs can show up on an X-ray. An X-ray can also show which areas of the lung are affected.

Pulmonary function tests

By performing a variety of tests called pulmonary function tests (PFTs), the doctor can find out how well the lungs are doing their job of expanding and exchangingoxygen and carbon dioxide with the blood. The lungs of patients with sarcoidosis cannot handle these tasks as well as they should; this is because granulomas and fibrosis of lung tissue decrease lung capacity and disturb the normal flow of gases between the lungs and the blood. One PFT procedure calls for the patient to breathe into a machine called a spirometer. It is a mechanical device that records changes in the lung size as air is inhaled and exhaled, as well as the time it takes the patient to do this.

Blood tests

Blood analyses can evaluate the number and types of blood cells in the body and how well the cells are functioning. They can also measure the levels of various blood proteins known to be involved in immunological activities, and they can show increases in serum calcium levels and abnormal liver function that often accompany sarcoidosis.

Blood tests can measure a blood substance called angiotensin converting enzyme (ACE). Because the cells that make up granulomas secrete large amounts of ACE, these enzyme levels are often high in patients with sarcoidosis. Blood ACE levels, however, are not always elevated in people with sarcoidosis, and increased ACE levels can also occur in other illnesses.

Bronchoalveolar lavage

This test uses an instrument called a bronchoscope - a long, narrow tube with a light at the end - to wash out, or lavage, cells and other materials from inside the lungs. This wash fluid is then examined for the amount of various cells and other substances that reflect inflammation and immune activity in the lungs. A high number of white blood cells in this fluid usually indicates an inflammation in the lungs.

Biopsy

Microscopic examination of specimens of lung tissue obtained with a bronchoscope, or of specimens from other tissues, can tell a doctor where granulomas have formed in the body and can provide the ultimate diagnosis.

Gallium scanning

In this procedure, the doctor injects the radioactive chemical element gallium-67 into the patient's vein. The gallium collects at places in the body affected by sarcoidosis and other inflammatory conditions. Two days after the injection, the body is scanned for radioactivity. Increases in gallium uptake at any site in the body indicate that inflammatory activity has developed at the site and give an idea of which tissue, and how much tissue, has been affected. However, since any type of inflammation causes gallium uptake, a positive gallium scan does not necessarily mean that the patient has sarcoidosis.

Slit-lamp examination

An instrument called a slit lamp, which permits examination of the inside of the eye, can be used to detect silent eye damage from sarcoidosis.