Modified fluorescence in situ hybridization methods using pathology archives

Brain tumors, like many other common tumors, are frequently associated with chromosomal numerical abnormalities. However, as the identification of abnormal characteristics by conventional cytogenetic or molecular methods has been hampered by technical difficulties, minimal information has been available about specific chromosomal or locus-specific gene alterations. Recently, fluorescence in situ hybridization (FISH) has emerged as a powerful clinical and research tool for the assessment of genomic instability within interphase nuclei. Here, we developed a modified FISH protocol including short-term microwave treatment to analyze specimens from the pathology archives that had been routinely processed and stored. The FISH signals obtained using this modified method showed a significant improvement compared with those obtained using the standard FISH method. This new technique thus enables the analysis of various paraffin-embedded tissue sections of intracranial tumors obtained under inappropriate fixation conditions. We highlight the advantages of this modified FISH procedure on a tissue microarray of archival materials for current diagnostic and investigative neuropathology applications.