A 45-year-old woman has pain in her fingers on exposure to cold, ahralgias, and difficulty swallowing solid food. The most useful test to make a definitive diagnosis is

The symptoms of Raynaud's phenomenon, ahralgia, and dysphagia point toward the diagnosis of scleroderma. Scleroderma- systemic vasculopathy of small and medium-sized vessels, excessive collagen deposition in tissues, and an abnormal immune system. Affect women more than men. There are two variants of scleroderma-- CREST syndrome and a more severe diffuse disease. Antinuclear antibody occurs in only 20 to 30% of patients with the disease, but a positive test is highly specific. Cardiac involvement may occur, and an ECG could show hea block or pericardial involvement. Renal failure can develop insidiously. Rheumatoid factor is nonspecific and present in 20% of patients with scleroderma.