Genomic aberration detection by fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) is a simple, rapid, and reliable method for detecting genomic alterations relevant to a wide range of diseases, particularly neoplastic disorders, using routine surgical and cytological specimens. By employing fluorescent-labeled nucleic acid or nucleotide analog probes to target specific DNA sequences on chromosomes, FISH facilitates accurate diagnosis, tumor classification, biomarker identification, selection of targeted therapies, and monitoring of treatment efficacy. As the technology continues to evolve, the demand for FISH is expected to grow, given its cost-effectiveness in supporting diagnostic and therapeutic decisions. However, to fully leverage the potential of this powerful technique, it is essential to be mindful of its underlying chemistry, potential artifacts, interpretive challenges, and the broader clinical context. This article provides an overview of the fundamental principles of FISH data analysis, addresses technical considerations and implementation challenges, and discusses diagnostic criteria, cutoff values, quality control measures, test validation processes, and interpretation of results - with a focus on its application in daily surgical pathology practice.