Mena et al listed criteria for the diagnosis of anaplastic hemangiopericytoma of the central nervous system. The authors are from the Armed Forces Institute of Pathology (AFIP) and Walter Reeed Army Institute of Research in Washington, D.C.
Types of hemangiopericytomas arising in the central nervous system:
(1) differentiated
(2) anaplastic
Criteria for an anaplastic hemangiopericytoma - all 3 of the following:
(1) necrosis
(2) > 5 mitoses in 10 high powered fields (x400 magnification)
(3) 2 or more of the following:
(3a) hemorrhage
(3b) moderate to marked nuclear atypia
(3c) moderate to high cellularity
where:
• There probably are 3 categories. The lowest grade tumor would show none of these findings. An intermediate grade tumor may show some but not all of these features.
An anaplastic hemangiopericytoma:
(1) is associated with shorter median survival (62 months vs 144 months if differentiated)
(2) a higher rate of recurrence after resection
(3) a greater risk for distant metastases
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