Scleroderma is a chronic autoimmune disease in which the immune system mistakenly attacks healthy tissues in the body. This triggers an overproduction of collagen, a component of scar tissue leading to the formation of the characteristic patches of thick and hardened skin. Excess collagen also may accumulate in different organs and cause damage.
There are different types of scleroderma with different symptoms, which can make diagnosis difficult. They can be grouped broadly in two categories as localized scleroderma, which usually affects the skin only, or systemic scleroderma, when internal organs also are affected.
There is no single test to diagnose scleroderma, and patients may have to undergo several tests to exclude other conditions before a conclusion is reached. Tests also may be carried out as part of the diagnosis to see which organs the disease has affected.
A physical examination will be done by a doctor to check for the common symptoms of scleroderma, such as skin changes. This includes the typical thick or tight patches of skin, digital ulcers, or calcium deposits under the skin called calcinosis. The doctor also may ask about other common symptoms, such as Raynaud’s phenomenon, heartburn, difficulty swallowing, fatigue, breathlessness, or joint pain.
A biopsy involves surgically removing a small tissue sample to be examined under a microscope and tested in a laboratory. A skin biopsy may be taken from an altered patch of skin to help diagnose scleroderma.
Blood tests are commonly used to diagnose scleroderma, as they can identify the presence of autoantibodies. Antibodies normally are produced by the immune system to identify and foreign substances. However, in autoimmune conditions, the body produces “autoantibodies,” which target proteins present in healthy tissues.
Not every scleroderma patient will have autoantibodies, and the type of autoantibody may vary. But the most common autoantibody detected in 60 to 80 percent of patients, regardless of scleroderma type, is antinuclear antibody (ANA). The presence of ANA alone does not confirm a diagnosis of scleroderma, as it can be present in other immune disorders such as lupus.
About 60-80 percent of limited systemic scleroderma patients can test positive for anticentromere antibodies (ACA). Diffuse systemic scleroderma patients will test positive for antibodies against topoisomerase-1 (Scl-70 antibodies) in about 30 percent of cases.
Blood tests can also reveal whether kidney function has been affected, which can occur in systemic sclerosis.
Tests for Raynaud’s phenomenon
Raynaud’s phenomenon is one of the most common symptoms of systemic scleroderma, therefore a diagnosis often will include tests for Raynaud’s. These tests include:
- Thermography on the hands, which uses an infrared camera to detect the level of heat generated. This can be coupled with a water test, which assesses how the hands respond to immersion in cold water.
- Nailfold capillaroscopy, which examines the small blood vessels under the fingernails.
Lung function tests
The lungs, or the blood vessels of the lungs, are commonly affected in systemic scleroderma patients. Tests may be done to assess how well the patient can breathe.
Heart function tests
Systemic scleroderma often can affect the heart, either through scarring of the heart tissue itself or conditions such as pulmonary arterial hypertension (PAH) putting strain on the heart. The two tests used to assess the heart rhythm and function are:
- Electrocardiogram, to measure the electrical signals across the heart
- Echocardiogram, which uses ultrasound to produce an image of the heart
The digestive system can be affected by systemic scleroderma and may be diagnosed through an endoscopy. This involves inserting a small flexible tube with a camera through the mouth or nose, to check for abnormalities in the esophagus and intestines.
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