BACKGROUND: Intravesical bacillus Calmette-Guerin (BCG) is used in the treatment and prophylaxis of carcinoma in situ of the urinary bladder and for the prophylaxis of primary or recurrent stage Ta and T1 papillary tumors following transurethral resection. Significant systemic complications are rare but have been reported.

CASE REPORT: We describe this case of Mycobacterium bovis psoas abscess and worsening abdominal aortic aneurysm following BCG therapy for bladder cancer. A 76-year-old male presented with a fever of a few days. He had a computed tomography (CT) scan of abdomen and pelvis that showed left iliopsoas fluid collection measuring 6.7×3.8 cm and an abdominal aortic aneurysm that had almost doubled in size from 4.9 cm to 8.5 cm. The patient underwent CT-guided aspiration of the iliopsoas collection. Mycobacterium bovis was isolated from the aspirate cultures. He had received intravesical BCG therapy for bladder cancer a few years prior.

CONCLUSIONS: The rapid increase in the size of the abdominal aortic aneurysm (mycotic aneurysm) in our patient was most likely due to BCG therapy. The risk-benefit assessment of this treatment should be carefully considered especially in patients with a pre-existing vascular aneurysm.

Keywords: Mycobacterium bovis, Psoas Abscess