Malignant transformation of WHO grade I meningiomas after surgery or radiosurgery : systematic review and meta-analysis of observational studies.

Background:The incidence and clinical features of the malignant transformation of benign meningiomas are poorly understood. This study examined the risk of the malignant transformation of benign meningiomas after surgery or stereotactic radiosurgery.Methods:We systematically reviewed studies published between 1979 and 2019 using PubMed, Scopus, and other sources. We analyzed pooled data according to the PRISMA guideline to clarify the incidence rate of malignant transformation (IMT) and factors affecting malignant transformation in surgically or radiosurgically treated benign meningiomas.Results:IMT was 2.98/1000 patient-years (95% confidence interval [CI] = 1.9-4.3) in 13 studies in a single-arm meta-analysis. Although the evidence level of the included studies was low, the heterogeneity of the incidence was mostly explained by the tumor location. In meta-regression analysis, skull base tumors had a significantly lower IMT than non-skull base tumors, but no gender association was observed. IMT after radiosurgery in 9 studies was 0.50/1000 person-years (95% CI = 0.02-1.38). However, a higher proportion of skull base tumors, lower proportion of males, and lower salvage surgery rate were observed in the radiosurgery group than in the surgery group. The median time to malignant change was 5 years (interquartile range = 2.5-8.2), and the median survival after malignant transformation was 4.7 years (95% CI = 3.7-8) in individual case data.Conclusion:IMT of benign meningioma was significantly affected by the tumor location. Radiosurgery did not appear to increase IMT, but exact comparisons were difficult because of differences in study populations

Metastatic skull tumors: MRI features and a new conventional classification

Skull metastases are malignant bone tumors which are increasing in incidence. The objectives of this study were to characterize the MR imaging features, locations, and extent of metastatic skull tumors to determine the frequency of the symptomatic disease, and to assess patient outcomes. Between September 2002 and March 2008, 175 patients undergoing routine head MR imaging were found to have metastatic skull tumors. Contrast-enhanced study with fat suppression was used in some cases when required. Classification of metastases was simplified to three yes/no questions: first, with regard to location (either in the calvarium or in the cranial base); second, with regard to distribution within the plane of the cranial bone (either “circumscribed” meaning clearly demarcated and confined to one bone, or “diffuse” and likely to spread across a suture to another bone); and third, with regard to invasion (“intraosseous” in cranial bones only, or “invasive” spreading from the skull, either out into the scalp or inward to the dura and perhaps further in). Primary sites were breast cancer (55%), lung cancer (14%), prostate cancer (6%), malignant lymphoma (5%), and others (20%). The mean time from primary diagnosis to skull metastasis diagnosis was 71 months for cases of breast cancer, 26 months for prostate cancer, 9 months for lung cancer, and 4 months for malignant lymphoma. Calvarial circumscribed intraosseous metastases were found most frequently (27%). The patients were mainly asymptomatic. However, some patients suffered from local pain or cranial nerve palsies that harmed their quality of life. Treatment, mainly for symptomatic cases, was by local or whole-skull irradiation. Metastatic skull tumors are not rare, and most are calvarial circumscribed intraosseous tumors. MR images contribute to understanding their type, location, and multiplicity, and their relationship to the brain, cranial nerves, and dural sinuses. Radiation therapy improved the QOL of patients with neurological symptoms