Rationale: Coronary artery aneurysms and fistulas are not rare conditions in clinical practice, but bilateral fistulas with a giant coronary aneurysm in just one person are quite rare.
Patient concerns: We report a case of a 66-year-old woman with these 2 coronary abnormalities accompanied with a huge mediastinum mass.
Interventions: The giant aneurysm was ligated and the mass was resected which was proved to be an organized hematoma finally.
Outcomes: The patient was discharged soon with no complications.
Lessons: The best treatment of giant coronary aneurysm is not clear because of its rarity, surgical resection may be the right procedure for the potential serious complications like this case.