Objective: Up to 70% of typical meningiomas demonstrate allelic loss at chromosome 22q. Allelic loss at additional chromosomal loci is associated with atypia and anaplasia in meningiomas. The pattern of allelic loss or loss of heterozygosity (LOH) follows a nonrandom, multistep pattern.
Methods: All surgical meningioma samples obtained from 1991 to 1992 at the University of Pittsburgh Medical Center were analyzed according to current World Health Organization criteria. Samples without constitutional deoxyribonucleic acid (DNA) were excluded from this analysis. Individual hematoxylin and eosin slides from 43 patients were microdissected, and the DNA was harvested and amplified in the presence of 24 pairs of polymerase chain reaction primers, representing 24 microsatellite loci. The polymerase chain reaction products were subjected to capillary gel electrophoresis and a fluorescence-based DNA analysis system. LOH was defined as ratios of allelic peak heights falling within a conservative threshold of less than 0.5 or more than 2.0. Fisher's exact test and receiver operator characteristic curves were used to test the relationship between benign versus atypical and malignant pathological features and LOH at specific loci or combinations of loci.
Results: On review by two independent pathologists, 34 benign meningiomas, 6 atypical meningiomas, and 3 anaplastic meningiomas were identified. The mean number of alleles with LOH was 1.5 +/- 1.2 for benign meningiomas, 6.7 +/- 2.7 for atypical meningiomas, and 8.3 +/- 2.3 for anaplastic meningiomas (P < 0.001). The most important individual loci to predict malignancy were D1S407 (P = 0.006), L-myc (P < 0.001), D10S520 (P = 0.003), D10S1173 (P = 0.042), D11S1920 (P < 0.001), D14S555 (P = 0.041), D17S1289 (P < 0.001), D22S417 (P = 0.001), D22S431 (P = 0.019), and D22S532 (P = 0.028). Combining the LOH data across loci, the area under the receiver operator characteristic curve was 0.993, corresponding to virtually perfect prediction of pathological characteristics.
Conclusion: Microsatellite marker analysis of allelic loss is a useful method of predicting atypia and anaplasia in meningiomas. More regions of allelic loss are seen in anaplastic and atypical meningiomas as compared with benign meningiomas. This study confirms previously reported chromosomal regions of allelic loss in atypical and anaplastic meningiomas and suggests additional chromosomal regions that may represent heretofore uncharacterized deletions within meningiomas. This type of genetic fingerprint ultimately may serve both a diagnostic and therapeutic role.