Increased preoperative levels of circulating erythrocytic hemoglobin are independent predictors for high-grade histology in falcine and parasagittal meningiomas

Background - Falcine and parasagittal meningiomas share a large histological heterogeneity and account for the highest rate of high-grade lesions among intracranial meningiomas.The ability to preoperatively estimate the lesion’s grade and clinical outcome would be of great value in orienting and customizing the treatment approach in these patients. To date, no validated clinical or radiological predictive factors for tumoral grade and prognosis are available. Materials & Methods - This is a single-center, retrospective, clinical study designed to assess the diagnostic and prognostic role of pre-operative peripheral blood markers in patients harboring falcine (FM) and parasagittal (PM) high-grade meningiomas. Overall, 121 patients undergoing surgical resection for a single FM/PM lesion at San Raffaele Hospital between November 2007 and April 2021 were included. A propensity score-matched analysis has been performed to account for gender imbalances in the low- grade (LG) vs high-grade (HG) cohorts. Results - Among the included lesions, 75 were falcine (62%), and 46 parasagittal (38%) meningiomas. The median tumoral volume was 31.1 cm3 (IQR 17.1-65.4). Low-grade lesions comprised n=77 WHO grade 1 tumors, whereas the high-grade group (HG) included n=35 grade 2 (28.9%), and n=9 grade 3 lesions (7.4%). Patients harboring HG lesions showed significantly higher baseline Hb levels compared to LG (mean 14.4 ± 1.59 vs 13.7 ± 1.25 g/dl, p=0.04). Pre-operative Hb demonstrated a predictive value of lesional grade (OR 1.35, 95% CI: 1.01-1.85, p=0.04). Accordingly, patients showing increased Hb levels >15.4 g/dl achieved shorter OS (60.4 months, 95% CI: 14.7-106.1 vs 137.4 months, 95% CI: 111.2-163.6), p=0.0011 compared to patients with lower pre-operative Hb values. Conclusions - Increased levels of circulating erythrocytic hemoglobin might be independent predictors for high-grade histology, and correlate with shorter overall survival in falcine and parasagittal meningiomas. This work indeed represents one of the earliest reports of such association, however, additional studies are needed to better define the diagnostic and prognostic role of these pre-operative markers in the context of intracranial lesions.