SESSION TITLE: Disorders of the Mediastinum 1 SESSION TYPE: Fellow Case Reports PRESENTED ON: 10/08/2018 03:15 pm - 04:15 pm INTRODUCTION: Spontaneous bronchial artery rupture is an uncommon cause of hemomediastinum. Observed in less than 1% of all selective bronchial arteriography cases, this condition is often associated with an underlying secondary process. Here we review a case of sporadic bronchial artery rupture presenting as a mediastinal mass. CASE PRESENTATION: A 64-year-old man with a history of smoking and poorly controlled hypertension presented to our institution after awakening with sharp chest pain, diaphoresis, and pre-syncope. He was hemodynamically stable aside from mild tachycardia. A contrast-enhanced chest CT revealed a 7 cm posterior mediastinal mass extending to the level of the sub-carina (figure 1) with compression upon the left atrium, and an associated left pleural effusion. Concern for a neoplastic process led to bronchoscopy. The mucosa of his central airways were pale with violaceous, linear striations along the posterior membrane. Fine needle aspiration (FNA) of the mass with endobronchial ultrasound (EBUS) was non-diagnostic. Following the procedure, we re-evaluated his imaging with thoracic radiology who identified a bronchial artery pseudoaneurysm (PSA) with extravasation into the lesion. Angiography confirmed the presence of an aberrant bronchial artery, and selective transcatheter embolization with coils and Gelfoam pledgets (figure 2) achieved stasis without further visualization of the defect. Repeat imaging 12 weeks later demonstrated new segmental pulmonary emboli, but otherwise no discernable change in size of the mediastinal collection. Subsequent bronchoscopy with EBUS guided sampling again yielded non-diagnostic results. DISCUSSION: Atraumatic, spontaneous hemomediastinum due to rupture of a bronchial artery PSA is an uncommon and portentous clinical event. We found less than 100 cases of this disorder upon review of the available literature. Symptoms can vary greatly, and range from atypical chest pain to frank hemoptysis and cardiovascular collapse. A low threshold of suspicion is necessary, and CT angiography is the diagnostic study of choice. Early selective embolization is the preferred management, with operative intervention reserved for select cases. CONCLUSIONS: We present a rare case of spontaneous bronchial artery rupture with resultant hemomediastinum. Despite initial diagnostic uncertainty, contrast enhanced imaging and multidisciplinary evaluation facilitated proper recognition and management. Our case highlights not only an uncommon diagnosis, but also the multifaceted evaluation often required to identify and treat potentially overlooked entities such as this. Reference #1: Sheffield, E. A., et al. “Massive haemoptysis caused by spontaneous rupture of a bronchial artery.” Thorax 43.1 (1988): 71. Reference #2: Kalangos, Afksendiyos, et al. “Ruptured mediastinal bronchial artery aneurysm: a dilemma of diagnosis and therapeutic approach.” The Journal of thoracic and cardiovascular surgery 114.5 (1997): 853-856. Reference #3: Seo, Yeon-Ho, and Jin Young Kwak. “Spontaneous hemomediastinum and hemothorax caused by a ruptured bronchial artery aneurysm.” The Korean journal of thoracic and cardiovascular surgery 44.4 (2011): 314. DISCLOSURES: No relevant relationships by Elliot Backer, source=Web Response No relevant relationships by Allison Backer, source=Web Response no disclosure on file for Farhad Mazdisnian; No relevant relationships by Joseph Phillips, source=Web Response