Fig 4. A 39-year-old man (patient 7) who underwent total laminectomy 7 years before the MR imaging examination. Sagittal T2-weighted image (A) shows a posterior paravertebral mass with low-signal-intensity and multifocal high-signal-intensity spots at the L4–5 level. Axial and sagittal T1-weighted images with contrast enhancement (B and C) show a mass with heterogeneous strong enhancement. Initial radiologic differential diagnosis was abscess, neurogenic tumor, and gossypiboma. Grossly, the mass did not contain a surgical gauze, but histopathologically, the cut surface of the mass contained suture threads surrounded by attenuated fibrosis related to the foreign body reaction.