Evidence of Tumor Exit From the Outlet Foramina of Fourth Ventricle Predicts Ependymoma in Pediatric Patients With Cerebellar/Fourth Ventricular Tumors.

INTRODUCTION Use of imaging to predict pre-operative likelihood of histopathology in pediatric tumors involving the cerebellum and/or fourth ventricle is potentially beneficial to the neurosurgical and neuro-oncological teams. The objective of the current report was to assess the correlation between radiologic evidence of tumor exit from the outlet foramina of the fourth ventricle with final histopathologic diagnosis. METHODS In 50 consecutive pediatric patients who underwent craniotomy for primary resection of a cerebellar neoplasm, pre-operative MRI was reviewed for evidence of tumor exit from the outlet foramina of fourth ventricle. RESULTS Evidence of tumor exit from the outlet foramina of fourth ventricle on MRI was found to be especially predictive of ependymoma. Specifically, this radiologic finding was 90% specific (37/41) and 100% sensitive (9/9) for histopathologic diagnosis of ependymoma. Of note, 2 of 18 medulloblastomas and 2 of 2 grade IV gliomas also demonstrated evidence of tumor exit. CONCLUSION Evidence of tumor exit from the outlet foramina of fourth ventricle on pre-operative MRI predicts histopathologic diagnosis of ependymoma with high accuracy. [ABSTRACT FROM AUTHOR]