Differentiation of localization of spinal hemangioblastomas based on imaging and pathological findings.

Intramedullary + extramedullary hemangioblastomas with largely extramedullary growth are rare and often incorrectly assigned as intradural-extramedullary tumors preoperatively. Preoperative evaluation of the precise tumor location is important for total resection of tumor and improving the surgical outcome. The aim of this study was to provide the first identification of the key differences among of preoperative MR images of hemangioblastomas in different locations and to correlate these with pathological findings. The subjects were 26 patients with surgery for spinal hemangioblastoma in our department, including 6 with an intramedullary tumor who were complicated with von Hippel Lindau disease. Intramedullary, intramedullary + extramedullary, and intradural-extramedullary tumors were present in 22, 3 and 1 cases, respectively. Sagittal MR images showed that intramedullary and intramedullary + extramedullary tumors gave intramedullary T2 high intensity areas (HIAs) spreading toward the craniocaudal sides of the tumor, whereas such findings were absent for the intradural-extramedullary tumor. All the tumors showed strong contrast on axial images, with focal enhancement of hemangioblastomas limited to the intramedullary region (focal type); smooth boundary lines between the spinal cord and the extramedullary tumor (smooth type); and a snowman sign for intramedullary + extramedullary tumors, which provided a key characteristic for differentiating intramedullary + extramedullary tumors from those limited to the extramedullary region. In pathological findings, the Ki67 activity was less than 1% for intramedullary and intradural-extramedullary tumors, but 18-25% in all cases with an intramedullary + extramedullary tumor. In conclusion, on preoperative MRI, a change in the intramedullary HIAs spreading the craniocaudal sides of the tumor on sagittal T2 weighted image (T2WI) and a snowman sign on contrast axial T1WI may be important for differentiation among spinal hemangioblastomas in different locations. Pathologically, we found that intramedullary + extramedullary hemangioblastoma has high cell proliferative activity, which may suggest that enlargement of this tumor occurs faster than that of intramedullary hemangioblastoma.