Diagnosing Sarcoidosis

Sarcoidosis is a condition that causes inflammation. It can occur in multiple organs, but it most often involves the lungs and lymph nodes. Doctors don’t know exactly what causes the condition, but they believe it may arise from the immune system’s response to environmental triggers. The experts at NYU Langone use a number of tests to accurately diagnose sarcoidosis. 

Normally, the immune system responds to harmful substances or stimuli by releasing special cells to protect your body. These cells cause inflammation, but once the harmful substance is gone, the inflammation diminishes. In people with sarcoidosis, however, the inflammation does not subside and inflammatory cells called granulocytes clump together. These clumps, or granulomas, appear in various organs and affect their structure and, occasionally, their function. 

In most people, sarcoidosis is acute, or sudden, and resolves on its own in a few weeks without treatment. In some instances, however, sarcoidosis becomes progressive and causes serious complications. Rarely, people with the condition have subtle symptoms that worsen over the course of weeks or months. This is considered chronic sarcoidosis and may require long-term, extensive medical therapy. 

Symptoms and Risk Factors

Sarcoidosis is what’s known as a multisystem disorder. Although it most often affects the lungs and lymph nodes, it can affect any part of the body, with or without lung involvement. Other commonly affected sites are the skin, eyes, brain, liver, and heart.

Symptoms vary depending on the affected body parts. Sarcoidosis usually affects the lungs, so you may experience a cough, fever, and shortness of breath. If the lymph nodes are involved, they typically become enlarged. 

Sarcoidosis may also affect the skin, causing discolored, tender bumps. Occasionally, it may lead to a condition called lupus pernio, in which discolored lesions appear on different parts of the body—especially the face. Sarcoidosis can also affect the eyes, causing blurry vision or light sensitivity. It may cause arthritis, fever, joint pain, and fatigue. 

Rarely, the condition can affect the heart or brain and cause an irregular heartbeat, shortness of breath, or headache. Serious complications, such as heart failure, can occur if the heart is involved. Meningitis may occur if the brain is affected. Sometimes several organs are affected at the same time, which can make treating sarcoidosis a challenge.

Sarcoidosis tends to affect people between the ages of 20 and 60. Certain groups are at higher risk than others. In the United States, African Americans have a greater chance of developing the condition than other groups. Those with a family history of sarcoidosis also have an elevated risk. 

Diagnostic Tests

To diagnose sarcoidosis, your doctor takes a medical history and conducts a thorough physical exam. He or she looks for signs of sarcoidosis on the skin, eyes, and lymph nodes. He or she may also order several different tests, including blood and imaging tests.

Blood Tests

Your doctor may take a sample of your blood and test it for markers of inflammation. Inflammatory markers can be helpful in diagnosing the condition, especially if sarcoidosis is affecting organs other than your lungs. Your doctor may also test your blood for evidence of conditions that mimic sarcoidosis, such as tuberculosis

Chest X-Ray 

If you have a cough or shortness of breath, your doctor may order a chest X-ray, a painless test that uses beams of light to create an image of the structures in your chest, such as your heart and lungs. These images may reveal scar tissue, granulomas, or enlarged lymph nodes. 

CT Scan

A CT scan uses X-rays and a computer to create three-dimensional, cross-sectional images of the body. This test can reveal the extent of sarcoidosis-related lung damage and the presence of granulomas. 

Pulmonary Function Test

Pulmonary function testing assesses lung function and possible damage by measuring how much air your lungs can hold, how quickly you can inhale and exhale, and how much oxygen your lungs deliver to the blood. 

Spirometry is the test most commonly used to measure pulmonary function. It measures how much and how quickly you can move air out of your lungs. During this test, you breathe into a mouthpiece attached to a recording device called a spirometer. The results may be printed out on a chart for your doctor to analyze. People with sarcoidosis may have trouble exhaling a normal amount of air.

Bronchoscopy With Biopsy

If sarcoidosis appears to affect your lungs, your doctor may perform a bronchoscopy, a test that enables him or her to closely examine these organs. Your doctor inserts a bronchoscope, a thin, flexible tube with a light and a camera on the end, through your nose or mouth. With the help of a video monitor, he or she guides the instrument through the airways. 

The doctor uses tiny instruments threaded through the bronchoscope to remove lung tissue samples, which are sent to a lab. A pathologist—a doctor who studies diseases in the laboratory—can help rule out or confirm a diagnosis of sarcoidosis.

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