Diagnostic Challenges in Spondylodiscitis After Endoscopic Retrograde Cholangiopancreatography Mimicking Malignancy and Radiculopathy.

Endoscopic retrograde cholangiopancreatography (ERCP) is a common procedure for biliary tract diseases, but it can rarely be followed by severe infectious complications such as spondylodiscitis. We present a 57-year-old woman who developed severe low back and leg pain after ERCP performed on 10 December 2025 for biliary sludge. An outside-hospital evaluation on 17 December 2025 documented fever, right upper quadrant pain, pneumobilia, and a catheter/stent-like structure within the bile duct with minimal surrounding fluid, raising concern for biliary infection. Initial laboratory results later showed markedly elevated C-reactive protein (75 mg/L), procalcitonin (0.6 ng/mL), vitamin B12 (>2000 pg/mL), and mildly increased tumor markers (CA 19-9 59.8 U/mL; CA 15-3 42 U/mL), initially raising concern for occult malignancy. Early sacroiliac magnetic resonance imaging demonstrated extensive inflammatory edema and was initially interpreted as reactive inflammation. Because pain persisted and inflammatory markers remained elevated despite initial treatment, dedicated lumbar magnetic resonance imaging was obtained after pain management reassessment on 18 February 2026; this confirmed aggressive L5-S1 spondylodiscitis with epidural abscess and psoas involvement. The patient improved after 6 weeks of intravenous antibiotic therapy. This case highlights how severe inflammation may produce biochemical red flags that mimic malignancy and underscores the value of multidisciplinary evaluation. Persistent post-procedural pain warrants diagnostic vigilance and timely dedicated spinal imaging even when early imaging is non-specific and microbiological confirmation is unavailable.