Proliferative activity in craniopharyngiomas: Clinicopathological correlations in adults and children

BACKGROUND Craniopharyngiomas are slow-growing, locally invasive intracranial tumors t hat can generate considerable morbidity, and recurrences are often difficul t to manage. Because reliable morphologic criteria for accurately predictin g the clinical outcome of these tumors are lacking, we evaluated the growth potential of craniopharyngiomas by measuring their proliferative activity based on MIB-1 immunostaining for the Ki-67 antigen, which is expressed dur ing all phases of the cell cycle except G(0). METHODS Paraffin sections from 37 cases of craniopharyngiomas were immunostained wi th the monoclonal antibody MIB-1, and a labeling index was derived in each case from an the with the highest labeling. RESULTS MIB-1 immunoreactivity was mainly confined to the peripheral palisaded epit helium of craniopharyngiomas. In adult craniopharyngiomas, MIB-1 labeling i ndices (MIB-LI) varied from 0.1% to 34.6% (mean 8.9%; SD 9.8), and in pedia tric tumors the indices ranged from 1.8% to 15.0% (mean 6.3%; SD 3.7). MIB- LI was not found to be an independent predictor of recurrence, although in all the pediatric cases that recurred, MIB-LI in the second specimen was gr eater. CONCLUSIONS The actively proliferating compartment in craniopharyngiomas seems to be th e peripheral palisaded epithelium. Low MIB-LI observed in the majority of t umors is in concordance with the slow growth and low-grade invasiveness ass ociated with craniopharyngiomas. However, unlike other intracranial neoplas ms, where Ki-67 labeling indices have been useful in predicting tumor behav ior, a clear relationship could not be demonstrated between MIB-1 immunorea ctivity, morphological features and clinical outcomes in adults or children with craniopharyngiomas. (C) 2000 by Elsevier Science Inc.