Invasiveness is associated with metastasis and decreased survival in hemangiopericytoma of the central nervous system

Meningeal hemangiopericytoma (m-HPC) is a rare tumor of the central nervous system (CNS), which is distinguished clinically from meningioma by its tendency to recur and metastasize. The histological classification and grading scheme for m-HPC is still evolving and few studies have identified tumor features that are associated with metastasis. All patients at our institution with m-HPC were assessed for patient, tumor, and treatment characteristics associated with survival, recurrence, and metastasis. New findings were validated using the SEER database. Twenty-seven patients were identified in our institutional records with m-HPC with a median follow-up time of 85 months. Invasiveness was the strongest predictor of decreased overall survival (OS) and decreased metastasis-free survival (MFS) (p = 0.004 and 0.001). On subgroup analysis, bone invasion trended towards decreased OS (p = 0.056). Bone invasion and soft tissue invasion were significantly associated with decreased MFS (p = 0.001 and 0.012). An additional 315 patients with m-HPC were identified in the SEER database that had information on tumor invasion and 263 with information on distant metastasis. Invasion was significantly associated with decreased survival (HR = 5.769, p = 0.007) and metastasis (OR 134, p = 0.000) in the SEER data. In this study, the authors identified a previously unreported tumor characteristic, invasiveness, as the strongest factor associated with decreased survival and metastasis. The association of invasion with decreased survival and metastasis was confirmed in a separate, larger, publicly available database. Invasion may be a useful parameter in the histological grading and clinical management of hemangiopericytoma of the CNS.