A 65-year-old woman presents to the emergency department because of shortness of breath and chest pain that started a few hours ago. She did not have a lever, expectoration, or any accompanying symptoms. She has a history ol right leg deep vein thrombosis that occurred 5 years ago. Some time later, she dies of severe respiratory distress. A pulmonary autopsy specimen reveals red loose mass that is lodged in the bifurcation of the pulmonary trunk with extensions into both the left and right main pulmonary arteries. Which of the following is the most likely diagnosis?