RADIOLOGY—CASE REPORT Pulmonary arteriovenous malformation: a rare anterior mediastinal mass Ryan Patrick Walklin, 1 James Entwisle, 1 Ying Kei Cheung 1 and Viswas Dayal 2 1 Radiology Department and 2 Department of Medicine, Wellington Regional Hospital, Wellington, New Zealand RP Walklin MBChB, PGDipSurgAnat; J Entwisle MBBC, MRCP, FRCR; YK Cheung DMRD, FRANZCR; V Dayal MBChB. Correspondence Dr Ryan Patrick Walklin, Radiology Department, Level 2, Wellington Regional Hospital, Riddiford Street, Newtown 6021, Wellington, New Zealand. Email: ryan.walklin@ccdhb.org.nz Conflict of interest: None. Submitted 28 April 2011; accepted 11 July 2011. doi:10.1111/j.1754-9485.2012.02361.x Summary Pulmonary arteriovenous malformations are rare pulmonary vascular lesions which are associated with Osler Weber Rendu syndrome (hereditary haem- orrhagic telangectasia). They act as right-to-left shunts and have cardiovas- cular and embolic complications. We present a patient with an apparent anterior mediastinal mass secondary to a pulmonary arteriovenous malfor- mations which was successfully treated percutaneously. Key words: body CT; chest imaging; vascular interventional radiology. Introduction We present a pulmonary arteriovenous malformation (AVM) presenting as an anterior mediastinal mass. Case An 82-year-old woman with Osler-Weber-Rendu syn- drome (Hereditary Haemorrhagic Telangectasia (HHT) ) presented to our institution’s Emergency Department with severe epistaxis. She has a long history of symp- tomatic anaemia secondary to complications of this disorder. On this presentation, she gave a further history of chronic impaired exercise tolerance and shortness of breath, which have previously been attributed to anaemia and comorbid ischaemic heart disease. Physical examination demonstrated hypoxia at rest and a loud continuous murmur at the left sternal border. Transthoracic echocardiography revealed no structural or valvular cardiac lesion corresponding to the audible murmur. Shunt analysis was not performed. Lateral chest radiograph (Fig. 1) demonstrated a large anterior mediastinal mass, and CT pulmonary angiography (GE Medical Systems BrightSpeed 16, Milwaukee, WI, USA) revealed a large AVM in the anterior mediastinum (Figs. 2–4). This was treated with percutaneous embo- lisation (Fig. 5), with immediate improvement in oxy- genation and exercise tolerance. Discussion The anterior mediastinum lies posterior to the sternum and anterior to the great vessels. It is bounded superi- orly by the thoracic inlet, laterally by the pleura and inferiorly by the heart. It contains the thymus or thymic remnant, internal thoracic vessels and fat. 1 Masses in the anterior mediastinum are uncommon. Their common differential is easily remembered as the mnemonic ‘the four T’s’, i.e. thyroid mass, thymic lesions, teratoma and (‘terrible’) lymphoma. They are typically suspected from a pathognomonic clinical presentation (i.e. dysphagia from a retrosternal goitre, or myasthenia gravis secondary to thymoma) or identified incidentally on imaging. Cross-sectional imaging is invaluable in determining the nature of anterior mediastinal masses. CT, in par- ticular, is readily available, and can assess calcification and vascularity, determine tumour stage and guide further investigation and treatment. Journal of Medical Imaging and Radiation Oncology 56 (2012) 545–547 © 2012 The Authors Journal of Medical Imaging and Radiation Oncology © 2012 The Royal Australian and New Zealand College of Radiologists 545