LOSS OF CHROMOSOME-22 AND CHROMOSOME-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 relat ively benign course. However, approximately 10% are diagnosed as atypi cal, anaplastic, or malignant and have worse prognosis. The genetic di fferences between the typical and higher grade meningiomas are not wel l characterized, although there appear to be increasingly complex kary otypic 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 interphas e cytogenetic techniques with paraffin-embedded archival material is d esirable for studying these neoplasms. To determine its accuracy in de tecting aneuploidy, we performed fluorescence in situ hybridization (F ISH) on 2-mu m paraffin section of nine previously karyotyped meningio mas using an alpha-satellite probe for chromosomes 14 and 22. Sections of normal tissue from six patients without malignancy were used as co ntrols. FISH analysis detected all of the chromosome losses in the men ingioma cases that had been characterized cytogenetically. In five cas es, cell lines not detected by standard cytogenetics were identified b y FISH. These results indicated that FISH is a reliable methods for de tecting chromosomal loss and may be more sensitive than standard cytog enetics alone. Furthermore, the results of this study support the conc ept that loss of chromosome 14 is associated with malignant progressio n in meningiomas.