Here is a "saddle embolus" that bridges across the pulmonary artery from the heart as it divides into right and left main pulmonary arteries. Such a saddle embolus is a cause for sudden death. This thromboembolus displays the typical gross appearance. The surface is somewhat irregular, and there are areas of pale tan to white admixed with dark red areas. The thrombus often has the outlines of the vein in which it formed.