Chromosomal aberrations in atypical and anaplastic meningiomas: A fluorescence in situ hybridization study

Objective: There is significant variability in the biologic behavior of meningiomas, especially of atypical and anaplastic meningiomas, that cannot be accounted for by just histology and grade of excision. The aim of our study was to analyze deletions in regions 22q, 18p11, 1p32, and 14q32 in grade II and grade III meningiomas and their correlation with tumor grade and recurrence. Materials and Methods: A total of 59 samples from 50 cases of grade II and grade III meningiomas were analyzed with fluorescence in situ hybridization (FISH) technique with locus specific probes. The types of aberrations and deletions were analyzed and correlated with the tumor status. Results: There was a statistically significant increase in deletions in recurrences when compared to primary surgeries. The mean mitotic index was higher in patients with deletions. Patients with 18p deletions tended to be younger and had a significant association with sheeting. 22q deletions were associated with hypercellular tumors. 1p, 14q, and 1p14q codeletion had a significant association with mitosis >= 7. Conclusion: This is a first study from India analyzing all these four sites for deletions using the FISH technique. Recurrent tumors and tumors with tendency to recur have a higher frequency of deletions. The FISH study can be used to predict the behavior of meningiomas if significant association is found. Further studies in larger sets of patients along with their clinical correlation would help in categorizing patients who have a higher risk of recurrence and help in guiding their clinical management.