Frequent NF2 mutations contribute to spinal location predominance and worse outcomes in psammomatous meningiomas

Abstract Purpose Psammomatous meningiomas (PMs) is a rare histological subtype of meningioma, but is rather frequent in spinal meningiomas. We are aimed to analyze the incidence, clinical features, molecular alterations, long-term outcomes, and prognostic factors of PMs. Methods We enrolled 151 patients with PMs, including 98 cranial PMs (CPMs) and 53 spinal PMs (SPMs), in this study. Clinical characteristics, molecular alterations, and progression-free survival (PFS) were analyzed in PMs. Targeted sequencing of meningioma-relevant genes was performed to determine the molecular alterations in PMs. Results PMs had a significant spinal location (p < 0.001) and female (p < 0.001) predominance, compared with the other grade 1 subtypes, and frequently associated with calcification (88.24%) and NF2 mutation (59.7%). During the long-term follow-up, 10 PMs (4 CPMs and 6 SPMs) recurred. Mutant NF2 was a significant predictor for worse PFS. Interestingly, SPMs exhibited distinct characteristics from CPMs. NF2 mutation was detected in all SPMs (48/48) but only in 38.46% (35/91) of CPMs, revealing a striking difference. Of note, SPMs showed a strong trend towards worse PFS than CPMs (p = 0.067) in all patients but not in patients with NF2 mutation (p = 0.65). The frequent NF2 mutation may have contributed to the spinal location predominance of PMs and worse PFS of SPMs. Conclusion PMs had significant female and spinal location predominance. NF2 mutation was an independent predictor for worse PFS of PMs. Of note, we discovered a striking difference in the rate of NF2 mutation in SPMs vs CPMs, which may have contributed to the spinal location predominance worse PFS of PMs.