P.340 Plate-guided distractor for a segmental mandibular defect

Abstract

To investigate the clinical and pathologic characteristics of primary intradural retroclival chordoma and improve the understanding of this rare disease.A retrospective study was conducted on six cases patients withof an intradural chordoma in the retroclival region who underwent surgery and were confirmed by pathology and imaging. Expression of brachyury, galectin-3, and Ki-67 in paraffin-embedded sections of the specimens was detected by streptavidin-peroxidase immunohistochemistry.Lesions were located in the subdural prepontine cistern. Computed tomography scan showed that the bone of the skull base was not destroyed, and findings on magnetic resonance imaging varied, resulting in a misdiagnosis of 50% of the cases in the preoperative imaging. All six cases were classified by their pathology into the classical subtype. They presented a strong positive staining for brachyury and galectin-3, and the Ki-67 labeling index was between 2.5% and 8.2%. Three cases presented no signs of recurrence or regrowth, whereas in the other three patients recurrence or regrowth occurred at 7∼14 months after initial surgery. Two patients died of this disease.Our study suggests that a positive staining for brachyury, galectin-3, and Ki-67 would be helpful for differential diagnosis, discriminating intradural retroclival chordoma from ecchordosis physaliphora and chordoid meningioma. Our study also shows that within intradural retroclival chordoma, there are significant prognostic differences. Tumors with an abundant blood supply, flake-like cellular arrangement, and a Ki-67 labeling index greater than 5% belong to a rapid-growth type and are prone to short-term recurrence and poorer prognosis.