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).

Signs and Symptoms

In addition to the lungs and lymph nodes, the body organs more likely than others to be affected by sarcoidosis are the liver, skin, heart, nervous system, and kidneys, in that order of frequency. Patients can have symptoms related to the specific organ affected, they can have only general symptoms, or they can be without any symptoms whatsoever. Symptoms also can vary according to how long the illness has been under way, where the granulomas are forming, how much tissue has become affected, and whether the granulomatous process is still active.

Even when there are no symptoms, a doctor can sometimes pick up signs of sarcoidosis during a routine examination, usually a chest x-ray, or when checking out another complaint. The patient's age and race or ethnic group can raise an additional red flag that a sign or symptom of illness could be related to sarcoidosis. Enlargement of the salivary or tear glands and cysts in bone tissue are also among sarcoidosis signals.

Lungs. The lungs are usually the first site involved in sarcoidosis. Indeed, about 9 out of 10 sarcoidosis patients have some type of lung problem, with nearly one-third of these patients showing some respiratory symptoms-usually coughing, either dry or with phlegm, and dyspnea. Occasionally, patients have chest pain and a feeling of tightness in the chest.

It is thought that sarcoidosis of the lungs begins with alveolitis (inflammation of the alveoli), the tiny sac like air spaces in the lungs where carbon dioxide and oxygen are exchanged. Alveolitis either clears up spontaneously or leads to granuloma formation. Eventually fibrosis can form, causing the lung to stiffen and making breathing even more difficult.

Eyes. Eye disease occurs in about 20 to 30 percent of patients with sarcoidosis, particularly in children who get the disease. Almost any part of the eye can be affected-the membranes of the eyelids, cornea, outer coat of the eyeball (sclera), retina, and lens. The eye involvement can start with no symptoms at all or with reddening or watery eyes. In a few cases, cataracts, glaucoma, and blindness can result.

Skin. The skin is affected in about 20 percent of sarcoidosis patients. Skin sarcoidosis is usually marked by small, raised patches on the face. Occasionally the patches are purplish in color and larger. Patches can also appear on limbs, face, and buttocks.

Other symptoms include erythema nodosum, mostly on the legs and often accompanied by arthritis in the ankles, elbows, wrists, and hands. Erythema nodosum usually goes away, but other skin problems can persist.

Nervous System. In an occasional case (1 to 5 percent), sarcoidosis can lead to neurological problems. For example, sarcoid granulomas can appear in the brain, spinal cord, and facial and optic nerves. Facial paralysis and other symptoms of nerve damage call for prompt treatment.

Laboratory Tests

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.

Many of the tests that the doctor calls on to help diagnose sarcoidosis can also help the doctor follow the progress of the disease and determine whether the sarcoidosis is getting better worse.

Chest X-ray. A picture of the lungs, heart, as well as the surrounding tissues containing lymph nodes, where infection- fighting white blood cells form, can give the first indication of sarcoidosis. For example, a swelling of the lymph glands between the two 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 (PFT), the doctor can find out how well the lungs are doing their job of expanding and exchanging oxygen and carbon dioxide with the blood. The lungs of sarcoidosis patients 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 test can measure a blood substance called angiotensin- converting enzyme (ACE). Because the cells that make up granulomas secrete large amounts of ACE, the enzyme levels are often high in patients with sarcoidosis. ACE levels, however, are not always high in sarcoidosis patients, and increased ACE levels can also show up in other illnesses.

Bronchoalveolar lavage. This is 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 of other tissues, can tell a doctor where granulomas have formed in the body.

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 also 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.

Kveim test. This test involves injecting a standardized preparation of sarcoid tissue material into the skin. On the one hand, a unique lump formed at the point of injection is considered positive for sarcoidosis. On the other hand, the test result is not always positive even if the patient has sarcoidosis.

The Kveim test is not used often in the United States because no test material has been approved for sale by the U.S. Food and Drug Administration. However, a few hospitals and clinics may have some standardized test preparation prepared privately for their own use.

The Kveim test is not used often in the United States because no test material has been approved for sale by the U.S. Food and Drug Administration. However, a few hospitals and clinics may have some standardized test preparation prepared privately for their own use.

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