Calcium pyrophosphate dihydrate crystal deposition disease (pseudogout) of lumbar spine mimicking osteomyelitis-discitis with epidural phlegmon.

Calcium pyrophosphate dihydrate crystal deposition disease (pseudogout) of the axial spine is rare. To our knowledge, there are few reports of the disease presenting with a presumed diagnosis of infection in the lumbar spine. As reported here, the diagnosis of osteomyelitis-discitis with epidural phlegmon was presumed before intervention. We present the case of a 60-year-old man with radiographic imaging and worsening clinical presentation at 2 consecutive hospitalizations. Axial magnetic resonance imaging originally showed increased signal intensity at the L5-S1 disk, which suggested an infectious rather than inflammatory process. Aspiration and biopsy at the time were nondiagnostic and showed no evidence of organisms. Two months after conservative treatment, the patient was readmitted with intractable low back pain and radiating bilateral leg pain. Repeat imaging showed increased interval signal in the L5-S1 disk, as well as enhancing soft-tissues that now extended to adjacent levels with extensive erosive changes. After surgical intervention for suspected infection, all cultures and stains for organisms were negative. Final pathology showed granulation tissue with focal inflammatory changes and calcium pyrophosphate crystal deposition. Although pseudogout is rare, physicians should add the disorder to the differential diagnosis for low back pain with radiculopathy and presumed infection.