Lumbosacral Vertebral Osteomyelitis With Iliopsoas and Epidural Abscess Following Intravesical Bacillus Calmette-Guérin Therapy.

Intravesical Bacillus Calmette-Guérin (BCG) therapy is the gold-standard adjuvant therapy for patients with superficial or non-muscle-invasive bladder cancer. BCG is a live attenuated strain of Mycobacterium bovis, which induces an antitumor environment, effectively fighting malignant uroepithelial cells through cytotoxic reactions. However, BCG therapy may stimulate local or disseminated infections. In rare cases, vertebral osteomyelitis may arise in the thoracolumbar spine, mostly affecting older males. This is a case of an 84-year-old male patient who developed L5-S1 osteomyelitis with associated epidural and iliopsoas abscess. Symptoms manifested as severe low back pain and bilateral lower extremity weakness. This paper aims to raise awareness of and educate spine surgeons in recognizing this uncommon complication by taking into context a history of BCG therapy.