Evaluation of 1p and 14q status, MIB-1 labeling index and progesterone receptor immunoexpression in meningiomas: Adjuncts to histopathological grading and predictors of aggressive behavior

Background: Meningiomas are benign central nervous system tumors; however, significant fraction recurs, irrespective of histological grade. Materials and Methods: We performed fluorescence in-situ hybridization for 1p36 and 14q32, and immunohistochemistry for progesterone receptor (PR), p53 and MIB-1 on 84 meningiomas. Results and Conclusion: Sixty-four were convexity tumors (30 grade I, 21 grade II, 13 grade III) and 20 petroclival (grade I; 10 with gross total resection (GTR), 10 with subtotal resection (STR)). Isolated 1p36 deletion was seen in 20% grade I, 28.6% grade II and 30.8% grade III convexity meningiomas, and isolated 14q deletion in one grade III convexity tumor. 1p/14q co-deletion was seen in none of grade I, 28.5% grade II and 30% grade III convexity meningiomas. PR immunoreactivity was less frequent in grade III tumors. Petroclival tumors did not show isolated deletion. However, 1p/14q co-deletion was seen in 20% of petroclival tumors with STR and in none with GTR. Frequency of chromosomal alterations and MIB-1 labeling index both increase with tumor grade. 1p/14q co-deletion is characteristic of grade II/III meningiomas, while PR immunoreactivity inversely correlates with grade, suggesting their use as surrogate markers for grading. Identification of 1p/14q co-deletion in grade I petroclival tumors with STR suggests that unresectable petroclival meningiomas are biologically more aggressive than their grade I convexity counterparts.