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Pulmonary arteriovenous fistula simulating a vanishing tumor.

In a patient with an asymptomatic left upper lobe pulmonary arteriovenous fistula, preoperative chest roentgenograms simulated bronchogenic carcinoma, but no overt feeding vessel was demonstrated. Intraoperatively no lesion could be palpated. Postoperative evaluation revealed a pulmonary arteriovenous fistula. This entity should be considered in the differential diagnosis of single or multiple pulmonary nodules. Careful review of chest roentgenograms for feeding arteries, or draining veins, and observation under fluoroscopy for changing size will aid in diagnosis, and potentially avoid bronchoscopy and possible transbronchoscopic biopsy of these vascular lesions.