A report of iliac muscle abscess due to Mycobacterium bovis after bacillus Calmette-Guerin therapy for bladder cancer.

Bacillus Calmette-Guerin (BCG) vaccine is traditionally used for vaccination against tuberculosis. BCG vaccine contains live attenuated strain of Mycobacterium bovis. Intravesical BCG is also effective in treatment of transitional cell carcinoma of the urinary bladder. Complications after intravesical BCG immunotherapy are extremely rare. We report an iliac muscle abscess due to M bovis that developed 4 years after intravesical BCG therapy for bladder cancer. Infection with M bovis, though rare, should be considered in patients with prior BCG therapy for bladder cancer.