Clinical Characteristics and Management of Infective Native Arterial Aneurysms Associated with BCG Therapy for Bladder Cancer

BACKGROUND: Intravesical Bacille Calmette-Guérin (BCG) immunotherapy is a well-established treatment for bladder cancer. Although generally safe, rare but severe complications such as Mycobacterium bovis-induced infected native arterial aneurysms (INAAs) can occur. These complications present diagnostic and therapeutic challenges due to their delayed onset and nonspecific symptoms. This systematic review aims to evaluate the causes, clinical presentation, diagnostic strategies, and management of BCG-induced INAA and to report an additional clinical case from the present institution.

METHODS: A systematic review of the literature was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 guidelines. PubMed was searched for English-language case reports published up to March 2025, describing arterial aneurysms as complications of intravesical BCG immunotherapy. Inclusion criteria required documented BCG treatment, no prior aneurysm, and microbiological or clinical confirmation of INAA.

RESULTS: A total of 56 case reports involving 58 patients were included. Most patients were male (98%) with a mean age of 72.2 years (standard deviation (SD) ± 7.7). Abdominal aortic aneurysms were most frequent (70.4%), followed by thoracic and peripheral aneurysms. The median interval between BCG instillations and INAA diagnosis was 12 months (interquartile range (IQR): 7.5-27.5). Treatment included open surgical repair (69%), endovascular repair (24.1%), and conservative management (3.5%). The median duration of antimicrobial treatment was 9 months (IQR 8-12). Overall mortality was 15.7%, and the complication rate was 33.3%.

CONCLUSION: BCG-induced INAA is a rare but life-threatening complication, and early recognition is critical. Optimal management involves targeted antimicrobial therapy and timely surgical intervention, either open or endovascular, based on the patient's condition and aneurysm characteristics.