Pulmonary veno-occlusive disease in a patient with unilateral absence of right pulmonary artery

A 25-year-old patient had unilateral absence of the right pulmonary artery (UARPA) and severe left pulmonary artery hypertension. After death from congestive right heart failure, autopsy revealed histologic signs of pulmonary veno-occlusive disease (PVOD) and pulmonary hypertension (PH). An accessory arterial vessel that was thrombotically occluded was found connecting the ascending aorta and the right pulmonary hilum. There was also histologic evidence of arterial thrombi within the right lung arterial vascular bed. The PH in UARPA usually occurs very early during the course of disease. From histologic findings and medical history, it is likely that in this case, late-onset elevation of pulmonary pressures was triggered by the occurrence of PVOD. This is the first case of UARPA and PVOD--a congenital unilateral arterial malformation in the presence of bilateral involvement in a possibly acquired venous obliterative disease.