Fluorescence in situ hybridization, comparative genomic hybridization, and other molecular biology techniques in the analysis of effusions.

Over the last 20 yr, the introduction of immunocytochemistry as a diagnostic tool has dramatically revolutionized diagnostic pathology. With the introduction of molecular methods as part of the diagnostic armamentarium, the practicing pathologist is facing the new challenge of grasping novel concepts of the molecular cytogenetics era. Herein, we review the diagnostic contribution of ancillary molecular techniques, including fluorescent and chromogenic in situ hybridization, telomerase assays, loss of heterozygosity, comparative genomic hybridization (CGH), and microarray-based CGH, for the practicing cytopathologists and discuss how these techniques will help pathologists in decision-making.