Focal hepatic activity during ventilation-perfusion scintigraphy due to systemic-portal shunt due to superior vena cava obstruction from histoplasmosis-induced fibrosing mediastinitis

A 59-year-old woman with a history of fibrosing mediastinitis secondary to histoplasmosis diagnosed on mediastinoscopy presented with dyspnea. A ventilation-perfusion scan demonstrated decreased perfusion to the entire right lung. In addition, the perfusion images demonstrated focal abnormal activity in part of the liver. On computed tomography of the chest, there was significant soft tissue opacification in the mediastinum occluding the right pulmonary artery, with passage of the injected contrast via collateral vessels to the liver. The main collateral pathway was via the right internal thoracic vein and the umbilical vein. Pulmonary angiography confirmed complete occlusion of the right pulmonary artery.