Radiation proctitis-related lumbar spondylodiscitis due to Actinomyces odontolyticus: a rare finding.

Lumbar spondylodiscitis due to radiation proctitis-related fistula is a rare finding in the literature. After having isolated Actinomyces odontolyticus, a rare finding in the osteomuscular system, we present one of such cases.A 75-year-old patient with a history of rectum adenocarcinoma, submitted to surgery and radiotherapy, presented himself in our emergency department with a 3-month history of lumbar pain radiating to both legs. Physical examination was compatible with cauda equina syndrome and subsequent investigation revealed L4-L5 spondylodiscitis. Despite a 6-month antibiotic therapy regimen, the symptoms recurred. Intravertebral disc biopsy revealed A. odontolyticus and directed antibiotic therapy was started. However, the symptoms recurred after a new 6-month antibiotic therapy regimen, this time with rectal purulent drainage. Additional study revealed two rectal fistulae. It was assumed those were caused by radiation proctitis and constituted the primary cause of spondylodiscitis. Laminectomy was performed with a satisfactory clinical response.