Presentation
Had surgery for disc herniation at L4-L5 one year ago, presented with purulent discharge from the previous lumbar surgical scar.
Patient Data
Well-defined ovoid structure in the right paraspinal region at L5-S1 level of low signal on T1, heterogeneous high signal on T2 centrally and high signal on T1, low signal on T2 peripherally with thick ring-like enhancement on postcontrast sequences. A fistulous tract is noted extending from this paraspinal ovoid structure to a subcutaneous ring enhancing collection.
On ultrasound the right paraspinal ovoid structure appears as an arciform echogenic structure with intense posterior acoustic shadowing, communicating with a thick heterogeneous subcutaneous fluid collection through a fistulous tract.
Case Discussion
The MRI and ultrasound features in a patient with a history of surgery is most consistent with an infected foreign body (gossypiboma), fistulised to the subcutaneous region with abscess formation, that was confirmed at surgery (infected surgical gauze was removed).