Do thoracic surgeons operate on splenic artery aneurysms?

Not in general: Splenic aneurysms are more often managed by vascular surgeons and/or interventional angiographers. Thoracic surgeons generally operate exclusively within the chest. However, there are thoracic surgeons that practice both cardiac/thoracic and vascular surgery.

No: Typically not. It is vascular surgeons. But if thoracic surgeopn has enough vascular experience.

Some do. : Some cardiothoracic surgeons operate on splenic aneurysms. Vascular surgeons and general surgeons also can operate on these cases. Interventional radiologist can often embolize the aneurysm so no surgery needed. (Image from Interventionalradiology.me)