Sclerodactyly, Raynaud's, ANA-positivity 'made the diagnosis' for systemic sclerosis
Click Here to Manage Email Alerts
Given the potential for false-positives in Scl-70 antibody testing for systemic sclerosis, many clinicians have overlooked the trio of classic signs and symptoms that would have otherwise “made the diagnosis,” according to a presenter here.
“We get about 15 to 20 referrals every week for scleroderma at the University of Michigan and out of them, seven to eight do not have systemic sclerosis or anything,” Dinesh Khanna, MD, MSc, of the University of Michigan Scleroderma Program, told attendees at the 2021 Congress of Clinical Rheumatology-East, noting that clinicians have become so focused on false positivity for anti-topoisomerase and positive antinuclear antibodies for Raynaud’s phenomenon, “so I wanted to spend some time going over how to diagnose systemic sclerosis.”
Source: Adobe Stock.
Khanna wasted no time in laying out the strongest diagnostic evidence for scleroderma.
“If someone has sclerodactyly — thickening of the skin over the fingers — that goes proximal to the MCP joint, you have made the diagnosis of systemic sclerosis,” he said. “You don’t need any autoantibodies; you don’t need any biopsies. There is only one disease that causes thickening of the skin that goes proximal to the MCP joint.”
In systemic sclerosis, approximately 95% of patients have sclerodactyly, 95% have a positive ANA by immunofluorescence and 90% have Raynaud’s phenomenon, an effective triad of diagnostic criteria even despite the possibility of false positives during ANA multiplex testing.
Khanna noted that “if you start to see patients that do not have these, start thinking about scleroderma-like disorders,” such as eosinophilic fasciitis, scleredema, scleromyxedema and nephrogenic systemic fibrosis.
However, it is also important for clinicians to fine-tune their criteria for Raynaud’s phenomenon.
“Cold hands is not Raynaud’s phenomenon,” Khanna told attendees. “If a patient comes to you and says, I have cold fingers and cold feet, that is not Raynaud’s phenomenon. As described by Morris Raynaud, Raynaud’s phenomenon is a triphasic color change from pallor [white] to cyanosis [blue] to rubor [red] when there is a dilatation of atrial venous anastomosis with an influx of oxygenated blood.”
Asking patients some preliminary screening questions such as “Are your fingers unusually sensitive to cold?” and “Do your fingers change color when exposed to cold temperatures?” can help clinicians to narrow diagnosis.
Just as Raynaud’s phenomenon should be closely examined, Khanna noted that ANA multiplex testing should also get a closer look from referring clinicians.
“I get calls from colleagues saying, ‘I have a patient who is ANA-positive, looks like scleroderma but all these three antibodies are negative,’” Khanna said. “However, only 50% to 60% of patients in the U.S. cohorts have one of these: anti-centromere, anti-Scl-70 and anti-RNA polymerase III. We have been able to identify about 92% of the scleroderma-specific autoantibodies, so there are cases we still see who are ANA-positive, but I cannot identify a specific autoantibody in that patient population.”
Collapse
Khanna D. Management of Systemic Sclerosis. Presented at: Congress of Clinical Rheumatology-East annual symposium; August 12-15, 2021 (hybrid meeting).
Click Here to Manage Email Alerts