Case Report of an Infectious Aortic Aneurysm Following Intravesical Bacillus Calmette‐Guérin Therapy After Transurethral Resection of a Bladder Tumor

ABSTRACT Introduction Intravesical Bacillus Calmette‐Guérin (BCG) therapy is an established treatment for non‐muscle‐invasive bladder cancer. Although systemic BCG infection is rare, infectious aortic aneurysm is a potentially fatal complication. Case Presentation A man in his 70s underwent transurethral resection of a bladder tumor followed by intravesical BCG therapy. One year later, computed tomography revealed a saccular abdominal aortic aneurysm with extensive periaortic inflammation and an iliopsoas abscess. Polymerase chain reaction analysis confirmed Mycobacterium bovis BCG infection. Despite antituberculosis therapy, aneurysmal rupture with abscess progression occurred, necessitating prosthetic graft replacement with omental flap coverage. The patient recovered without recurrence after prolonged therapy. Conclusion BCG‐related infectious aortic aneurysm may develop even in the absence of fever or marked inflammatory response. Clinicians should suspect and consider early CT evaluation in patients with a history of intravesical BCG therapy when unexplained retroperitoneal or vascular abnormalities are identified, regardless of inflammatory status.