Background: Bilateral vestibular schwannomas (VS) are pathognomonic of neurofibromatosis type 2 (NF2), but the diagnostic criteria also include unilateral VS (UVS) in combination with multiple meningiomas (MM) and other schwannomas, as well as MM without VS.
Objective: To investigate the diagnostic value of these criteria and establish the presence of other genetic conditions in patients presenting in this manner.
Methods: The Manchester International NF2 database was accessed to obtain information on patients presenting with a UVS and MM or ≥2 nonintradermal schwannomas (NIDS). We gathered data on patients diagnosed with NF2 due to MM without VS and on patients presenting with MM without meeting NF2 criteria. Analysis was performed for pathogenic variants (PVs) in NF2, SMARCE1, SMARCB1, and LZTR1.
Results: A total of 31 of 131 patients presenting with a UVS and MM had a nonrefuted diagnosis of NF2 after molecular studies, in comparison with 85 of 96 patients presenting with UVS and ≥2 NIDS (P ≤ .00001). Fifty percent of patients presenting with a UVS and ≥2 NIDS with NF2 developed bilateral VS, compared with only 26% of those who presented with a UVS and MM (P = .0046). In total, 11 of 152 patients presenting with MM without fulfilling NF2 criteria were found to have a PV in SMARCE1, and 7 of 152 were confirmed to have mosaic NF2.
Conclusion: Patients presenting with UVS and MM are significantly more likely to have a nonrefuted diagnosis of NF2 than patients presenting with UVS and ≥2 NIDS, but significantly less likely to develop bilateral VS. Seven percent of those presenting with MM without meeting NF2 criteria had PV in SMARCE1, and 5% had mosaic NF2.
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