Pulmonary thromboembolism as an atypical manifestation of mixed connective tissue disease in a young man: A case report.

Mixed connective tissue disease is an autoimmune disorder characterized by the presence of various abnormal autoantibodies and systemic involvement. Similar to systemic lupus erythematosus, pulmonary manifestations commonly include interstitial fibrosis, pulmonary hypertension, and pleurisy; however, pulmonary thromboembolism has rarely been reported in mixed connective tissue disease. We report a case of mixed connective tissue disease in which pulmonary thromboembolism was the initial manifestation, as diagnosed by computed tomography angiography. Following glucocorticoid and anticoagulant therapy, the thrombus resolved completely. This case highlights that in patients with mixed connective tissue disease, particularly those presenting with dyspnea or sudden-onset dyspnea, the possibility of pulmonary thromboembolism should not be overlooked.