title: Postoperative annular pseudocyst: report of two cases with an unusual complication after microdiscectomy, and successful treatment by percutaneous aspiration and steroid injection.
abstract: BACKGROUND
  After microdiscectomy for extruded disc fragments, patients may develop recurrent symptoms from numerous causes. Postoperative annular pseudocysts represent a unique entity not previously described in the medical literature.
  
  
  OBJECTIVE
  To report unique imaging findings in two patients who presented with recurrent radiculopathic symptoms after microdiscectomy. To report successful percutaneous aspiration and steroid injection in one of these cases.
  
  
  METHODS
  Report of two cases.
  
  
  METHODS
  Two patients underwent preoperative imaging with noncontrast magnetic resonance imaging (MRI) and postoperative imaging with pre- and postcontrast MRI. One of these patients underwent therapeutic computed tomography (CT)-guided aspiration and injection.
  
  
  RESULTS
  MRI demonstrated T2 hyperintense and enhancing collections, which conformed to the shape of the resected disc fragment and communicated with the disc annulus. One of these cases demonstrated enlargement over several months with worsening of symptoms. Aspiration of the lesion produced thick fluid. The patient experienced marked relief of symptoms after the aspiration and injection of steroid into the lesion.
  
  
  CONCLUSIONS
  The unique imaging findings in these patients represent a previously undescribed complication of microdiscectomy, which we have termed "postoperative annular pseudocyst." We have successfully treated one case with CT-guided percutaneous aspiration and injection.
authors.affiliation: Department of Radiology, Mayo Clinic, Jacksonville, FL 32224, USA.
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Young
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Fenton
authors.forename: Leo F
authors.initials: LF
authors.lastname: Czervionke
mesh_terms: D000328:Adult; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage; D001707:Biopsy, Needle; D003560:Cysts / Q000209:etiology / Q000473:pathology* / Q000628:therapy*; D017586:Diskectomy / Q000009:adverse effects*; D005938:Glucocorticoids / Q000008:administration & dosage; D006801:Humans; D007268:Injections, Epidural; D007405:Intervertebral Disc Displacement / Q000503:physiopathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology / Q000473:pathology* / Q000628:therapy*; D014222:Triamcinolone Acetonide / Q000008:administration & dosage
chemical_list: D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D014222:Triamcinolone Acetonide