Patient A was a 73-year-old male who presented to the emergency department (ED) with abdominal pain and low-grade fevers. He presented 6 months after the last of his five intravesical BCG instillations for his known non-muscle invasive urinary bladder papillary TCC. His medical profile included COPD, Type II diabetes, hypertension, dyslipidemia, and macular degeneration. There was history of remote TB exposure in childhood with no treatment or related hospital admissions. In ED, his complete blood cell count was within normal limits. Serum C-reactive protein was elevated at 58.6 mg/L (normal: 0-8.0 mg/L). Initial cross sectional imaging at the time of presentation demonstrated a new, multi-septated peripherally enhancing 6.3 cm x 1.9 cm x 5.6 cm, low-density collection within the retrocrural/posterior mediastinal region abutting the descending thoracic aorta along 180 degrees of circumference of the vessel (Fig. 1). Along the right posterolateral wall, an enhancing focal outpouching arising from the descending thoracic aorta was also identified. On positron emission tomography/computed tomography (PET/CT), this lesion demonstrated peripheral intense hypermetabolism with central photopenia. PET/CT did not demonstrate any additional hypermetabolic lesions and was negative for tumor recurrence or metastatic disease elsewhere. A follow-up MRI of the thoracic spine was negative for discitis or osteomyelitis. CT-guided aspiration of the retrocrural abscess yielded mycobacterium bovis consistent with BCG on pathology. Given the constellation of findings and pathology results, the patient was treated with Isoniazid, rifampin, pyrazinamide, ethambutol, and Vitamin B6. Given the patient's medical comorbidities, the mycotic aneurysm identified on CT was treated with endovascular stent graft placement as opposed to open surgical repair. No post-procedural complications were identified on CT. Adjunctive percutaneous drainage of the periaortic collection was also performed. Subsequently, over a course of 6 months the patient has remained asymptomatic, although the lesion has shown no signs of regression.