Focal myositis presenting as pseudothrombophlebitis of the neck in a patient with mixed connective tissue disease.

This report describes a case of focal myositis in a patient with mixed connective tissue disease. The patient presented with diffuse neck swelling and pseudothrombophlebitis of the left internal jugular vein. Other clinical features included a high fever, elevated erythrocyte sedimentation rate, and prompt improvement after administration of high-dose intravenous corticosteroid therapy. Criteria for polymyositis were absent, serum levels of creatine kinase remained normal, and there was no sign of recurrence during 3 years of followup. Results of immunoprecipitation for anti-Jo-1 and other myositis-specific autoantibodies remained negative in serial serum samples obtained before, during, and after the episode.