BackgroundHere, we report a rare case of massive hemothorax caused by rupture of an intercostal artery pseudoaneurysm associated with pyogenic spondylitis, which was successfully treated with endovascular intervention.Case presentationA 49-year-old man with schizophrenia, idiopathic esophageal rupture, postoperative mediastinal abscess, and pyothorax, diagnosed with pyogenic spondylitis caused by methicillin-resistant Staphylococcus aureus. Magnetic resonance imaging and computed tomography (CT) showed extensive vertebral body destruction. The patient underwent a two-stage operation: anterior vertebral debridement and fixation with iliac bone graft and posterior fixation with instrumentation. Seven days postoperatively, the patient’s right chest pain increased, his blood pressure dropped, and he had shock. Chest X-ray showed massive hemothorax in the right lung. Chest CT and subsequent intercostal arteriography showed a pseudoaneurysm in the right T8 intercostal artery and active contrast extravasation from it. This seemed ruptured mycotic aneurysms involving intercostal vessels. These vessels were successfully embolized using micro-coils. Then, the patient completed the prescribed antimicrobial therapy in the hospital without any complications.ConclusionsIntercostal artery aneurysms are rare vascular abnormalities. They have the risk of rupture and may sometimes cause hemothorax and can be potentially life-threatening. Septic embolization from infective endocarditis and contiguous spread of local infection can cause intercostal artery mycotic aneurysms. In this patient, the aneurysm was deemed caused by septic embolization, not surgical manipulation. There are no established criteria for treating intercostal artery aneurysms. Ruptured intercostal artery pseudoaneurysms are a good indication of endovascular intervention, and prompt embolization saved the life of the patient in this case report. Endovascular treatment should be the first choice even in ruptured cases. Doppler ultrasonography and CT are the most appropriate diagnostic modalities for evaluating intercostal artery pseudoaneurysms. In this patient, CT could depict an intercostal aneurysm. Appropriate diagnosis and prompt treatment of these rare vascular lesions are essential in preventing rupture. This case report highlights the possibility of a ruptured intercostal mycotic aneurysm in patients with pyogenic spondylitis and reminds physicians to be alert of this rare but potentially fatal complication.