Agenesis of the left pulmonary artery as a cause of hemoptysis.

Agenesis of a pulmonary artery is an unusual cause of hemoptysis. Presented here is a case of agenesis of the left pulmonary artery which presented following a subendocardial infarction which raised the suspicion for pulmonary embolus. Despite a ventilation perfusion long scan which showed absent perfusion to the left lung, the clinical absence of tachypnea and dyspnea led to pulmonary angiography and thence to the correct diagnosis. Anticoagulant and/or thrombolytic therapy were withheld and the patient was treated conservatively. Agenesis of a pulmonary artery is a rare cause of hemoptysis, but may mimic pulmonary emboli and should be considered in the differential diagnosis. Failure to recognize this clinical entity could lead to unwanted and potentially harmful anticoagulant or thrombolytic therapy.