Abdominal aortic aneurysmal and endovascular device infection with iliopsoas abscess caused by Mycobacterium bovis as a complication of intravesical bacillus Calmette-Guérin therapy.

Vascular complications after the intravesical instillation of Bacillus Calmette-Guérin (BCG) therapy are extremely rare. We experienced a case of abdominal aortic aneurysmal infection excluded by a stent graft with an iliopsoas abscess after intravesical instillation of BCG therapy that required reoperation. Five years ago, an 81-year-old man was diagnosed with transitional cell carcinoma of the bladder. After transurethral resection of the bladder tumor and intravesical BCG therapy, a radical cystectomy was performed. Twenty-four months after intravesical BCG therapy, follow-up an abdominal computed tomographic (CT) scan revealed an aortic abdominal aneurysm. Endovascular aneurysm repair was performed, and the aneurysm was excluded postoperatively. Thirty months after the endovascular aneurysm repair (and 54 months after intravesical BCG therapy), a follow-up abdominal CT revealed a low-density area in the right iliopsoas muscle that formed a fistula to the excluded aneurysm. We performed CT-guided iliopsoas abscess drainage and collected yellow pus. Polymerase chain reaction analysis revealed that the pus was positive for Mycobacterium tuberculosis complex. The patient was diagnosed with abdominal aortic aneurysmal infection associated with iliopsoas abscess caused by Mycobacterium bovis, and surgery was performed. We performed an extra-anatomical bypass and removed the stent graft with debridement. When the aneurysmal wall was incised and resected, yellow pus surrounded the stent graft. In addition, a large fistula was present between the right posterolateral aortic aneurysmal wall and the iliopsoas abscess cavity. After the operation, the histopathological examination of excised abdominal aortic aneurysmal wall tissue revealed an epithelioid granuloma with caseous necrosis involving multinucleated giant cells, indicating M tuberculosis complex infection. Although the intravesical instillation of BCG therapy is considered safe, complications resulting from vascular infections can arise in extremely rare cases. The complication described in this case report emphasizes the need to cautiously select treatment for a mycotic aortic aneurysm after intravesical instillation of BCG therapy.