A 45-year-old woman has pain in her fingers on exposure to cold, arthralgias, and difficulty swallowing solid food. She has a few telangiectasias over the chest but no erythema of the face or extensor surfaces. There is slight thickening of the skin over the hands, arms, and torso. What is the best diagnostic test?
A. Rheumatoid factorThe symptoms of Raynaud phenomenon, arthralgia, and dysphagia point toward the diagnosis of scleroderma. Scleroderma, or systemic sclerosis, is characterized by a systemic vasculopathy of small- and medium-sized vessels, excessive collagen deposition in tissues, and an abnormal immune system. It is an uncommon multisystem disease affecting women more often than men. There are two variants of scleroderma—a limited type (previously known as CREST syndrome) and a more severe, diffuse disease. Antinuclear antibodies are almost universal. Topoisomerase-I antibody occurs in only 30% of patients with diffuse disease, but a positive test is highly specific. Anti-centromere antibodies are more often positive in limited disease. Cardiac involvement may occur, and an ECG could show heart block but is not at all specific. Renal failure can develop insidiously, but BUN and creatinine levels would not be diagnostically specific. Rheumatoid factor is nonspecific and present in 20% of patients with scleroderma. Reproduction of Raynaud phenomena is nonspecific and is not recommended as an office test.