CLONAL ANALYSIS OF MENINGIOMAS

MENINGIOMAS ARE PRIMARY brain tumors arising from meningothelial cells . They usually grow slowly and are surgically easy to separate from th e brain. A recent clonal analysis of meningiomas, using methylation-se nsitive restriction fragment length polymorphisms, suggested a monoclo nal origin. Using the same technique but with a highly informative X c hromosome probe (M27 beta), we found that 17 (85%) of the 20 meningiom as analyzed were informative. Of the 17 informative tumors, 8 (47%) we re monoclonal, 3 (18%) had loss of heterozygosity on the X chromosome, and, unexpectedly, 6 (35%) had a polyclonal pattern. Samples from two areas of one tumor showed a monoclonal pattern and loss of heterozygo sity, respectively, on the X chromosome. A review of the histopatholog ical and radiological features of the 17 informative tumors did not he lp to distinguish the clonal from the polyclonal tumors. We conclude t hat meningiomas are heterogeneous in clonal composition.