Objective: To compare the efficacy of fluorescence in situ hybridization (FISH) by using chromosome-specific probes with standard cytology and cytogenetics for detection of hyperdiploid malignant cells in pleural effusions.
Material and methods: A blind study was done on 26 pleural effusions from 25 patients who had undergone thoracentesis (14 with and 11 without a malignant condition). Cytology, cytogenetics, and FISH with probes specific for chromosomes 7, 8, 12, 18, X, and Y were done on each pleural effusion. For FISH studies, malignant specimens were defined as having 8% or more of cells with hyperdiploidy.
Results: Results of cytology and FISH were both normal in each of the 11 patients with benign pleural effusions. Cytogenetic studies were successful in six of these patients: five were chromosomally normal, but one male patient had an abnormal clone that lacked a Y chromosome. Among the 14 patients with malignant pleural effusions, cytology and FISH were abnormal in 8 and 6, respectively. Cytogenetic studies were successful in 11 of these patients, and an abnormal clone was found in 5.
Conclusion: FISH can detect hyperdiploid malignant cells in pleural effusions and can be useful in the work-up of patients suspected of having malignant pleural effusions.