Etiology (What’s the cause?) – So far, there are only 2 known definitive factors that lead to meningioma development: (1) radiation, and (2) the gene associated with Neurofibromatosis type 2 (NF2). Most likely, meningiomas and other tumors in the brain and the rest of human body develop due to alterations or damages that have occurred in the patient’s gene(s) within certain chromosomes. Exactly what genes and what kind of alterations or damages lead to meningioma formation are still unknown other than the NF2 gene mentioned above. However, with the NF2 gene, located on Chromosome 22, the gene defect accounts for a fraction of all (non-NF2) meningioma patients (33%). Obviously, additional research is required to further elucidate the exact and all genetic changes that lead to meningioma formation.
Lee JH, Sundaram V, Stein JD, Kinney SE, Stacey DW, Golubic M: Reduced expression of schwannomin/merlin in human sporadic meningiomas. Neurosurgery 40:578-587 (1997)
Evans J, Jeun SS, Cowel JK, Harwalkar JA, Golubic M, Lee JH: Molecular alterations in the NF2 gene and its protein are rarely occurring in meningothelial meningiomas: J Neurosurgery 94:111-117, 2001
Pathology (What cell type and how aggressive?) – Meningiomas are classified using the World Health Organization (WHO) grading scale, from Grade 1 (benign) to Grade 3 (malignant). In a single institution review conducted by my group, 92% meningiomas belonged to WHO Grade 1 (benign), while 6% was WHO Grade 2 (aggressive or atypical) and 2% WHO Grade 3 (malignant) meningiomas. This pathologic classification is critically important in meningiomas because one of the factors that determine how well patients do long-term depends on this tumor “grade”. For example, only 3% of WHO Grade 1 tumors recur within 5 years of initial surgery, compared to 40% 5-year recurrence rate for WHO Grade 2 tumors, and 80% for WHO Grade 3 meningiomas.
Lee JH, Sade B, Choi E, Prayson R, Golubic M: Meningothelioma as the predominant histologic subtype of midline skull base and spinal meningiomas. J Neurosurgery 105:60-64, 2006
Prayson R: Pathology of meningiomas, In: Meningiomas (JH Lee, ed), Springer-Verlag, London, 2008