Diagnosis
The physician may suspect scleroderma after taking a history of the symptoms and performing a physical examination. As part of this examination, the physician does the following:
- Checks the skin for thickened and hardened areas. The major clinical clues to scleroderma are symmetrical hardening and thickening of the skin in any areas on the fingers and toes.
- Presses affected tendons and joints to detect crackling or grating sensations, which can indicate sclerodermic changes beneath the skin.
- Examines the fingernails underneath a microscope. The physician may detect changes in capillaries that are characteristic of scleroderma and mixed connective tissue disease.
Tests for Antinuclear Antibodies
Tests may be conducted to detect immune factors called antinuclear antibodies (ANAs). Elevated levels of ANA are found in 95% of patients with scleroderma. Antinuclear antibodies, however, are also strongly present in patients with many other autoimmune diseases, including systemic lupus erythematosus. Many people can also have high levels and never develop any of these diseases.
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Detecting ANA subtypes may provide some weight in diagnosing scleroderma. Such subtypes include the following:
- Anti-topoisomerase antibodies.
- Anti-centromere antibodies. The centromere is an important factor in cell division, and antibodies to centromeres are found in between 50% and 80% of people with CREST.
These antibodies are also found in other rheumatologic disorders, however, so detecting them does not necessarily prove scleroderma. At the same time, studies have found that specific antibodies are associated with specific aspects of the disease. Therefore, identifying their presence could help diagnose, treat, and monitor people with scleroderma. For example, the presence of anti-U1-RNP and anti U3-RNP is associated with muscle inflammation. Pulmonary hypertension and vascular disease is common with anticentromere antibodies (ACA). Pulmonary fibrosis is associated with antitopoisomerase (TOPO). Severe interstitial fibrosis rarely occurs in the presence of RNA Polymerase III (Pol 3), although this autoantibody is strongly present in patients with renal crisis. Among patients who have diffuse scleroderma, those with Pol 3 have the best survival rate.
Ultrasound
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