Thirty-nine cases of intracranial hemangiopericytoma and anaplastic hemangiopericytoma: A retrospective review of MRI features and pathological findings

ObjectiveTo retrospectively review the imaging features of surgically and pathologically confirmed intracranial hemangiopericytoma and anaplastic hemangiopericytoma.MethodsThirty-nine cases of surgically and pathologically confirmed hemangiopericytoma and anaplastic hemangiopericytoma were analyzed retrospectively. The MRI features were compared with pathological findings in all cases.ResultsOf the 39 cases, 21 were anaplastic hemangiopericytoma (WHO grade III) and the remaining cases were hemangiopericytoma (WHO grade II); all lesions were solitary. MRI of anaplastic hemangiopericytoma showed that 20 cases were lobulated, and nine grew cross-leaf. The lesions showed mixed iso-high-low signal (n = 20) or iso-signal (n = 1) on plain T1WI, and mixed high-low signal (n = 20) or iso-signal (n = 1) on plain T2WI. After contrast injection, marked heterogeneous enhancement was seen in 19 cases. Significant necrosis and cystic changes were seen in 16 cases, and the “dural tail sign” was found in two cases. Ten cases had bony destruction, and 16 showed significant peritumoral edema. In 18 cases of hemangiopericytoma, nine were oval-shaped and three grew cross-leaf. The lesions showed mixed iso-low signal (n = 10) or iso-signal (n = 8) on plain T1WI, and mixed iso-high signal (n = 10) or iso-signal (n = 8) on plain T2WI. After contrast injection, significant uniform enhancement was seen in 10 cases. Significant necrosis and cystic changes were seen in seven cases, and “dural tail sign” was seen in six cases. Two cases had bony destruction. No case showed significant peritumoral edema. Pathological immunohistochemical Ki67 staining showed a concentration of ∼18.4% positive cells in anaplastic hemangiopericytoma, whereas in hemangiopericytoma it was 7.12%.ConclusionImaging findings of intracranial anaplastic hemangiopericytoma had more pronounced lobulation, cross-leaf growth tendency, more and easier bleeding, more necrosis, more cystic changes giving rise to heterogeneous signals, rarer frequency of the “dural tail sign”, more damage near the skull, and more significant peritumoral edema than hemangiopericytoma. These features may help differentiate these two types of malignancy.