MIB-1 staining index of pediatric meningiomas

OBJECTIVE: For adult meningiomas, the staining index (SI) for the anti-Ki-6 7 monoclonal antibody MIB-1 is well correlated with histological atypia and tumor recurrence. MIB-1 Sis for meningiomas in the pediatric population ha ve not been previously reported. Meningiomas tend to be more histologically aggressive and to recur more frequently in children, compared with adults. The objectives of this study were to determine whether MIB-1 Sis are corre lated with pathological atypia and recurrence among pediatric meningiomas a nd to compare the MIB-1 Sis of pediatric meningiomas with those of adult me ningiomas. METHODS: MIB-1 Sis were assessed on paraffin-embedded sections of 14 pediat ric meningiomas (patient age, 2-17 yr), 5 of which contained atypical or ma lignant features. For comparison with benign pediatric meningiomas, MIB-l S is were also assessed on paraffin-embedded sections of 14 adult meningiomas (patient age, 38-90 yr), none of which displayed atypical or malignant fea tures or recurred within a 5-month median follow-up period. RESULTS: MIB-1 Sis of pediatric meningiomas ranged from 1.2 to 31.6% (media n, 9.1%). Significant differences were observed between the MIB-1 Sis for t umors with atypical or malignant features (median, 12.3%; range, 7.0-31.6%) and those for tumors without atypia (median, 7.0%; range, 1.2-12.6%; P = 0 .045). There were six recurrences after gross total resection, during a 36. 5-month median follow-up period. All five of the tumors with pathological a typia recurred; one tumor without atypia recurred. Significant differences were observed between MIB-1 Sis for nonrecurrent tumors (median, 6.6%; rang e, 1.2-12.2%) and those for recurrent tumors (median, 12.5%; range, 7.0-31. 6%; P = 0.012). The median MIB-1 SI for adult control specimens was 8.8% (r ange, 1.2-19.3%), which did not differ significantly from that for pediatri c meningiomas without atypia (P = 0.68). CONCLUSION: For this cohort of pediatric meningiomas, pathological atypia a nd the tendency to recur were correlated with elevated MIB-1 Sis. The media n MIB-1 SI for pediatric meningiomas without histological atypia did not di ffer significantly from that for adult meningiomas without atypia, suggesti ng that the more aggressive clinical features of meningiomas in children ma y be attributable to factors other than the rate of cellular proliferation.