An unexpected complication of bacillus Calmette-Guérin therapy.

A 78-year-old man presented with a history of fever and night sweats of 1-month duration. His relevant medical history was a transitional-cell bladder cancer treated with intravesical instillation of bacillus Calmette–Guérin (BCG) 5 months previously. Abdominal palpation revealed a pulsatile mass in the left lower quadrant. Laboratory tests only showed an elevated C-reactive protein at 5.7 mg/dl. Contrast-enhanced CT scan of the abdomen demonstrated a saccular aneurysm of the infra-renal aorta (Fig. 1) suggestive of mycotic aneurysm. An aneurysmal resection was then performed. Aerobic and anaerobic culture of the aortic tissue remained negative but a Ziehl–Nielsen stain was positive consistent with a mycobacterial infection. Acid-fast culture and PCR were positive for Mycobacterium bovis. The diagnosis of mycotic aneurysma following intravesical BCG therapy was then retained. Vascular complications after intravesical instillation of BCG, a live attenuated strain of Mycobacterium bovis, are extremely rare. Haematogenous or lymphatic spread is the most common hypothesis proposed to explain an arterial infection by M. bovis. Both medical and surgical approach are requested in the management of BCGinduced mycotic aneurysm. A combination with at least three antituberculous agents for 9–12 months is recommended. Pyrazinamide should not be used due to widespread resistance of M. bovis.