Loss of chromosomes 22 and 14 in the malignant progression of meningiomas. A comparative study of fluorescence in situ hybridization (FISH) and standard cytogenetic analysis.

The majority of meningiomas are classified as typical and have a relatively benign course. However, approximately 10% are diagnosed as atypical, anaplastic, or malignant and have a worse prognosis. The genetic differences between the typical and higher grade meningiomas are not well characterized, although there appear to be increasingly complex karyotypic changes associated with the higher grade tumors. Because higher grade meningiomas are not common tumors, and because of the inherent problems associated with the culturing of tumors, the use of interphase cytogenetic techniques with paraffin-embedded archival material is desirable for studying these neoplasms. To determine its accuracy in detecting aneuploidy, we performed fluorescence in situ hybridization (FISH) on 2-micron paraffin sections of nine previously karyotyped meningiomas using an alpha-satellite probe for chromosomes 14 and 22. Sections of normal tissue from six patients without malignancy were used as controls. FISH analysis detected all of the chromosome losses in the meningioma cases that had been characterized cytogenetically. In five cases, cell lines not detected by standard cytogenetics were identified by FISH. These results indicate that FISH is a reliable method for detecting chromosomal loss and may be more sensitive than standard cytogenetics alone. Furthermore, the results of this study support the concept that loss of chromosome 14 is associated with malignant progression in meningiomas.