Thrombocytosis in rheumatoid arthritis.

Thrombocytosis may occur in association with autoimmune, collagen, and malignant diseases (Levin and Conley, 1964; Bean, 1965; Selroos, 1972; Davis and Mendez Ross, 1973). In rheumatoid arthritis a positive correlation has been found between the platelet count and disease activity (Bean, 1965; Selroos, 1972; Hryszko et al., 1975; Hemandez, 1975; Hutchinson et al., 1976). Thrombosis is infrequent in rheumatoid arthritis and when present is usually related to coexisting arteritis. Thromboembolic complications have rarely been related to thrombocytosis (Davis and Mendez Ross, 1973). We report a patient with rheumatoid arthritis complicated by excessive thrombocytosis and recurrent arterial thrombosis who died of massive thrombosis of the aorta despite treatment with anticoagulants, corticosteroids, and azathioprine.