Rare case of a proximal descending thoracic aorta mycotic aneurysm following intravesical BCG injections for the treatment of bladder cancer.

A 79-year-old man presented with an enlarging thoracic aneurysm on the background of superficial bladder cancer treated with intravesical bacillus Calmette-Guérin (BCG) injections. Following the injections, he developed deranged liver function tests and hepatomegaly. Liver biopsy revealed granulomatous hepatitis compatible with disseminated mycobacterial infection (BCG-osis) and was treated with anti-tuberculosis agents for 12 months. A surveillance CT scan performed as a follow-up for his bladder cancer in 2018 revealed a saccular thoracic aneurysm at the ligamentum arteriosum, which was metabolically active on positron emission tomography (PET) scan. Given the timeframe from intravesical instillation of BCG and the metabolic activity on PET scan, the lesion was consistent with a mycotic aneurysm secondary to disseminated mycobacterial infection. Following multidisciplinary team discussion, a thoracic endovascular aneurysm repair was performed. The stent grafts were placed distal to the left subclavian artery with good angiographic results and no immediate postoperative complications. He was initiated on long-term antibiotics to cover potential bacterial pathogens including mycobacterium.