Pulmonary arteriovenous malformation masquerading as massive pulmonary thromboembolus.

We present a case of a 78-year-old male with hereditary haemorrhagic telangiectasia and severe hypoxia incorrectly diagnosed as pulmonary embolism following a false positive ventilation/perfusion scan. Anti-coagulation and thrombolysis was complicated by an upper gastro-intestinal haemorrhage. Pulmonary arteriovenous malformations resulted in a clinically significant right-left shunt and created an apparent perfusion defect evident upon radionuclide imaging, leading to diagnostic uncertainty and a potentially dangerous treatment modality.