title: Solid variant of aneurysmal bone cyst on the cervical spine of a child: case report, differential diagnosis and treatment rationale.
abstract: BACKGROUND
  Despite numerous descriptive publications, the nature, character, differential diagnosis and optimal treatment of aneurysmal bone cysts (ABCs), remain obscure. The authors report a case of the solid variant of aneurysmal bone cyst (S-ABC) occurring in the posterior components and body of C7 vertebra focusing on the differential diagnosis and surgical treatment rationale.
  
  
  METHODS
  Right shoulder and neck pain were the presenting symptoms of 9-year-old boy. Torticollis developed later on but no neurological deficit was found. Imaging revealed an osteolytic lesion with significant extraosseous extension. Although diagnosis favoured an ABC, imaging studies did not provide clear diagnostic criteria. CT guided biopsy performed preoperatively was also not directly diagnostic. Given that differential diagnoses included S-ABC but also giant cell tumor (GCT) of bone, decision was made to proceed with a staged, back and front, complete resection of the affected bony elements of C7. Preoperative spinal angiography showed supply to the tumor from the right ascending and deep cervical artery territories. Particle embolization was not performed due to the presence of ipsilateral supply to the anterior spinal artery at the C6 level and contralateral supply at the C7 level. Intraoperatively, histology taken from posterior elements, although again not clearly diagnostic, favoured S-ABC variant rather than GCT. Thus, initial plan was revised and anterior surgery was postponed as the extent of the dissection would have been dependent on the presumed diagnosis. The final histological report confirmed the diagnosis of an S-ABC. In view of this, it was decided to embolize the lesion to avoid a second stage anterior surgery. At embolization, repeat spinal angiography showed reduced tumor blush following the surgery. Distal branches of the deep cervical artery were occluded with platinum coils (avoiding the risks associated with the use of particles or liquid embolic agents). No further procedure was planned.
  
  
  CONCLUSIONS
  Imaging and histological pattern of this specific type of ABC, differential diagnosis from GCT and the surgical protocol followed with the patient consist of an interesting case of revising the initial plan, according to the upcoming histological reports.
authors.affiliation: Centre for Spinal Studies and Surgery, Nottingham University Hospitals NHS Trust, Queens Medical Centre Campus, Derby Road, Nottingham, NG7 2UH, UK.
authors.forename: Christos
authors.initials: C
authors.lastname: Karampalis
authors.forename: Robert
authors.initials: R
authors.lastname: Lenthall
authors.forename: Bronek
authors.initials: B
authors.lastname: Boszczyk
mesh_terms: D017824:Bone Cysts, Aneurysmal / Q000175:diagnosis* / Q000601:surgery; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D002648:Child; D003937:Diagnosis, Differential; D018212:Giant Cell Tumor of Bone / Q000175:diagnosis*; D006801:Humans; D008297:Male; D011859:Radiography; D013122:Spinal Diseases / Q000175:diagnosis* / Q000601:surgery