A Rare Case of Bronchomediastinal Pulmonary Vein Fistula due to Fibrosing Mediastinitis.

Fibrosing mediastinitis (FM) is a rare condition with extensive proliferation of fibrous tissue in the mediastinum usually happens few years after Histoplasma infection. FM usually occurs years later after presentation of Histoplasma infection, and usually what makes patients seek medical attention are symptoms from compression and occlusion of vital mediastinal structures, such as the central airways, superior vena cava, pulmonary arteries, and veins. Rarely, heart, pericardium, coronaries, and aorta are involved. We report a case of 39-year-old-male who was admitted with fever and cough. The patient's condition worsened despite being on broad-spectrum antibiotics, with worsening encephalopathy and a new onset lower extremity weakness. Brain imaging showed multiple strokes suggestive of embolic event. CT chest/abdomen was suggestive of FM along with cavitary lung nodules and pneumomediastinum. Splenic and renal infarcts were also noted. Infective endocarditis was one of the top differential diagnosis due to multiple embolic infarcts, and hence a transesophageal echocardiography (TEE) was pursued. TEE showed a mass along with air bubbles entering the left atrium from the pulmonary vein. On re-evaluation of CT chest images, a fistula was seen extending from the mediastinum to the left main bronchus and the left upper pulmonary vein. This supported the diagnosis of FM with erosion of lymph node into the left main bronchus and left upper pulmonary artery, leading to fistula formation and subsequent systemic air embolization. The diagnosis of FM requires a multimodality approach, high clinical suspicion, and accurate history taking. Treatment mainly aims at managing the mechanical complications.