Meningeal hemangiopericytomas: A clinicopathological study with emphasis on MGMT ( O 6 ‐methylguanine‐ DNA methyltransferase) promoter methylation status

Meningeal hemangiopericytomas ( HPC s) are aggressive dural‐based tumors, for which no prognostic or predictive marker has been identified. Gross total resection is treatment of choice, but not easily achieved; hence, alkylating agents like temozolomide ( TMZ ) are now being tried. O 6 ‐methylguanine‐ DNA methyltransferase ( MGMT ) promoter methylation has proven prognostic and predictive value in glioblastomas. This study evaluates MGMT promoter methylation in meningeal HPC s to determine its role in HPC oncogenesis and its association with patient outcome. Meningeal HPC s diagnosed between 2002 and 2011 were retrieved and clinicopathological features reviewed. MGMT promoter methylation status was assessed by methylation‐specific polymerase chain reaction ( MSP ) and immunohistochemistry ( IHC ) for MGMT protein. HPC s accounted for 1.1% of all CNS tumors. Forty cases were analyzed; the majority were adults (mean age = 41.4 years). Seventy percent were primary and 30% were recurrent tumors; 60% were grade II and 40% were grade III . MGMT promoter methylation was identified in 45% of cases, including Grade II (54.2%) and Grade III (31.3%) ( P  = 0.203). Promoter methylation was significantly ( P  = 0.035) more frequent in primary (57.1%) than in recurrent (16.7%) tumors. No correlation was noted between MGMT promoter methylation by MSP and MGMT protein expression by IHC , or with progression‐free survival. Thus, a significant proportion of HPC s demonstrate MGMT promoter methylation, suggesting possible susceptibility to TMZ . As promoter methylation is more frequent in primary tumors, TMZ may serve as a therapeutic option in residual primary tumors. Epigenetic inactivation of MGMT in HPC s necessitates the assessment of prognostic and predictive value of MGMT promoter methylation in HPC s in larger clinical trials.