We present the case of a 54-year-old patient who presented to our institution 4 months after refusing surgical treatment for a right upper lobe cavitary carcinoma. Weight loss, hemoptysis, and worsening pulsatile chest pain were the complaints. Radiologic restaging surprisingly revealed a large pulmonary artery pseudoaneurysm occupying the whole cavity area. A right pneumonectomy with intrapericardial pulmonary artery ligation was performed. Previous cases are extremely rare and differ from ours as patients presented with advanced lung cancer and thus, were not treated with resection, but with coil embolization.