Subclavian Artery Branch Pseudoaneurysm Rupture With Massive Hemothorax in a Patient With Neurofibromatosis Type 1

Neurofibromatosis type 1 is a rare disorder that occurs secondary to pathogenic variants in the NF1 tumor suppressor gene on chromosome 17. Characteristic clinical manifestations include multiple hyperpigmented macules, axillary and inguinal freckling, optic gliomas, and numerous skin neurofibromas. Vasculopathies are a rare complication of this disease and can affect vessels ranging from the proximal aorta to small arterioles, with pathology including arterial stenosis, aneurysms, and arteriovenous malformations. Aneurysms in these patients are often asymptomatic, and most patients with this complication appear for treatment after vessel rupture. We describe a 33-year-old man with neurofibromatosis type 1 who presented with chest pain and was ultimately found to have a ruptured left subclavian artery branch pseudoaneurysm leading to a large hemothorax.