How to diagnose Sarcoidosis ? 

Your doctor will diagnose sarcoidosis based on your medical history, a physical exam, and test results. He or she will look for granulomas (inflamed lumps) in your organs. Your doctor also will try to rule out other possible causes of your symptoms.
                
Medical History
                
Your doctor may ask you detailed questions about your medical history. For example, he or she may ask whether you:
                
Have a family history of sarcoidosis.
                
Have had any jobs that may have raised your risk for the disease.
                
Have ever been exposed to inhaled beryllium metal. (This type of metal is used to make aircrafts and weapons.)
                
Have had contact with organic dust from birds or hay.
                
Exposure to beryllium metal and organic dust can cause inflamed lumps in your lungs that look like the granulomas from sarcoidosis. However, these lumps are signs of other conditions.
                
Physical Exam
                
Your doctor will check you for signs and symptoms of sarcoidosis. Signs and symptoms may include red bumps on your skin; swollen lymph nodes; an enlarged liver, spleen, or salivary glands; or redness in your eyes. Your doctor also will check for other causes of your symptoms.
                
Your doctor may listen to your lungs and heart. Abnormal breathing or heartbeat sounds could be a sign that sarcoidosis is affecting your lungs or heart.
                
Diagnostic Tests
                
You may have tests to confirm a diagnosis and to find out how sarcoidosis is affecting you. Tests include a chest x ray, lung function tests, biopsy, and other tests to assess organ damage.
                
Chest X Ray
                
A chest x ray is a painless test that creates pictures of the structures inside your chest, such as your heart and lungs. The test may show granulomas or enlarged lymph nodes in your chest. About 95 percent of people who have sarcoidosis have abnormal chest xrays.
                
Lung Function Tests
                
Lung function tests measure how much air you can breathe in and out, how fast you can breathe air out, and how well your lungs deliver oxygen to your blood. These tests can show whether sarcoidosis is affecting your lungs.
                
Biopsy
                
Your doctor may do a biopsy to confirm a diagnosis or rule out other causes of your symptoms. A biopsy involves taking a small sample of tissue from one of your affected organs.
                
Usually, doctors try to biopsy the organs that are easiest to access. Examples include the skin, tear glands, or the lymph nodes that are just under the skin.
                
If this isn't possible, your doctor may use a positron emission tomography (PET) scan to pinpoint areas for biopsy. For this test, a small amount of radioactive substance is injected into a vein, usually in your arm.
                
The substance, which releases energy, travels through the blood and collects in organs or tissues. Special cameras detect the energy and convert it into three-dimensional (3D) pictures.
                
If lung function tests or a chest x ray shows signs of sarcoidosis in your lungs, your doctor may do a bronchoscopy (bron-KOS-ko-pee) to get a small sample of lung tissue.
                
During this procedure, a thin, flexible tube is passed through your nose (or sometimes your mouth), down your throat, and into the airways to reach your lung tissue. (For more information, go to the Health Topics Bronchoscopy article.)
                
Other Tests To Assess Organ Damage
                
You also may have other tests to assess organ damage and find out whether you need treatment. For example, your doctor may recommend blood tests and/or an EKG (electrocardiogram).
                
If youre diagnosed with sarcoidosis, you should see an ophthalmologist (eye specialist), even if you dont have eye symptoms. In sarcoidosis, eye damage can occur without symptoms.