Abstract
A 65-year-old woman visited our hospital with a complaint of acute onset dyspnea and radiological manifestations of pulmonary thromboembolism. The patient underwent an exploratory surgery to find a whitish-blue colored mass occupying almost the whole lumen of the main pulmonary arteries. Based on the pathological and radiological findings, the patient was diagnosed to have a pulmonary arterial intramural hematoma. Intramural hematomas are usually observed in the walls of the aorta, and we believe that an isolated intramural hematoma in the pulmonary artery has not been described previously.