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Friday, March 7, 2014
Arthritis and Rheumatism
Is it Possible to Not Have Scleroderma While Testing Positive for Scl-70?
When my blood was tested for ANA, which always has a low positive, they also did a panel for other more specific antibodies. I tested positive for SCL-70. However, I have none of the obvious symptoms of scleroderma. My doctor said that this is the fifth or sixth time in the past year that this particular labrotory has given him a positive SCL-70 for someone who had no obvious symptoms of scleroderma, and so he thinks it is likely a false positive. Are false positives common? If the test was not a false positive, do I definitely have scleroderma, perhaps "sine scleroderma"? Or, can the antibody show up before the symptoms do, and I will likely develop scleroderma later? Or, can you have a positive SCL-70 and never get scleroderma? Thank you so much for your expert opinion.
The Scl-70 antibody, also known as anti-topoisomerase antibody, is a blood test that is most commonly associated with Systemic Sclerosis (SSc), also known as scleroderma. Scl-70 is present approximately 60% of the time in the diffuse variant of SSc and is present about 30% of the time in the limited variant of SSc.1 A review of literature by Drs. Reveille and Solomon in 2003 suggests that the Scl-70 antibody is relatively specific for scleroderma. However, it is still possible to have an elevated Scl-70 antibody and not have scleroderma. There is a small possibility that the laboratory is related to another connective tissue or even the benign, primary variant of Raynaud's phenomenon (RP). RP is present in about 95% of individuals that have scleroderma. It certainly may precede other features of SSc, such as skin thickening, by several years.
- Walker UA, et al. Clinical risk assessment of organ manifestations in systemic sclerosis: a report from the EULAR Scleroderma Trials and Research group database. Ann Rheum Dis 2007;66:754-763.
- Reveille JD, Solomon DH. Evidence-based guidelines for the use of immunologic tests: anticentromere, Scl-70, and nucleolar antibodies. Arthritis Care & Research 2003;49:399-412.
Raymond Hong, MD, MBA, FACR
Formerly, Assistant Professor of Medicine
School of Medicine
Case Western Reserve University