A 45-year-old man has had progressive dyspnea on exertion with fatigue for the past 2 years. On auscultation of his chest he has a prominent pulmonary component of S2, a systolic murmur of tricuspid insufficiency, and bruits over peripheral lung fields. Jugular venous distension is present to the angle of his jaw when sitting. Laboratory studies show antiphospholipid antibodies. CT angiography shows eccentric occlusions with pulmonary arteries and mosaic attenuation of pulmonary parenchyma. Which of the following is the most likely disease process causing his pulmonary disease?

Over half of persons with chronic pulmonary thromboembolism with pulmonary hypertension do not have a history of recurrent pulmonary embolism. Rather than one large life-threatening embolus, chronic thromboembolism occurs from multiple smaller emboli that reduce the pulmonary vascular bed and increase pulmonary pressures, leading to cor pulmonale. Recanalization of thrombi leads to narrow channels causing the bruits. Antiphospholipid antibodies pose a risk for thrombosis. The risk factors for systemic arterial atherosclerosis are not operative in the pulmonary arterial tree, and pulmonary atherosclerosis is a consequence of pulmonary hypertension, not a cause of it. Pneumonitis with parenchymal inflammation reduces ventilation more than perfusion. Sarcoidosis is an idiopathic granulomatous disease that mainly affects the pulmonary parenchyma. ANCA-associated vasculitis of the pulmonary arterial tree may produce vascular occlusion, but there is usually parenchymal disease as well, along with multisystem involvement.