Hematogenous Staphylococcus aureus discitis in adults can start outside the vertebral body

Textbooks describe hematogenous discitis in adults as starting in the anterior vertebral body near the endplates.

Hematogenous Staphylococcus aureus discitis developed at L1-L2 in an 81-year-old woman. On the first magnetic resonance imaging (MRI) scan performed 4 days after symptom onset, the only abnormalities were high signal from the disk on T2-weighted images, gadolinium enhancement of the soft tissues anterior to L1-L2, and epidural involvement. The endplates and vertebral bodies were normal. A subsequent MRI scan showed features typical of infectious discitis.

We found a single similar case report in the medical literature, indicating that discitis starting outside the anterior vertebral body is rare. Nevertheless, an increasing number of similar cases may be diagnosed in the future, as MRI is being performed increasingly early in patients with a clinical suspicion of infectious discitis.

Hematogenous infectious discitis in adults may start in some patients within the disk, soft tissues anterior to the disk, or epidural space. To avoid diagnostic and therapeutic delays, physicians should be aware of this unusual presentation of infectious discitis on very early MRI scans. When the clinical picture suggests discitis and findings from the early MRI scan are atypical, a repeat MRI scan should be obtained 1 week later to confirm the diagnosis.