Pulmonary arteriovenous fistula: A rare cause of erythrocytosis

Various chronic pulmonary diseases can cause hypoxia mediated erythrocytosi s. We report on a 46 year old male patient presenting with erythrocytosis, in whom a pulmonary arteriovenous fistula on the basis of a vascular malfor mation was identified as a rare cause of hypoxic erythrocytosis. Thus, cong enital pulmonary vascular malformations can become clinically manifest in a dvanced age.