Detection of the human telomerase RNA component by in situ hybridization in cells from body fluids

Objective: To apply in situ hybridization (ISH) detection of human telomerase reverse transcriptase (hTERT) mRNA expression in abnormal cells in body fluids to evaluate its usefulness in the diagnosis of malignant effusions. Study Design: We investigated the expression of hTERT mRNA by ISH in 33 fluid samples from 30 patients, including 1 cerebrospinal fluid, 18 pleural fluids, 1 pericardial fluid, 12 peritoneal fluids and 1 bronchial washing. Comparison of the results of ISH with those of conventional cytologic evaluation was also performed. Results: Cytomorphologic examination of the 33 body fluids allowed classification as malignant, suspicious, atypical and benign conditions. Among the 17 malignant conditions, there were 15 cases positive by both cytology and ISH. There were 9 discrepant cytology-ISH results in patients with various conditions, including 2 cases positive by cytology and inconclusive by ISH, 5 cases suspicious by cytology and positive by ISH, and 2 cases atypical by cytology and negative by ISH. Among the 9 benign conditions, there were 8 cases negative by both cytology and ISH and 1 case negative by cytology and positive by ISH. This test was highly sensitive (90%) and specific (91 %) and had favorable positive (95%) and negative (83%) predictive values. Conclusion: Expression of the hTERT mRNA component can be easily detected by ISH in malignant cells from body fluids. This method is especially useful when the abnormal cell population in the fluid consists of limited numbers of suspicious cells that cannot be completely differentiated from reactive mesothelial cells and thus may help differentiate true positive cases from false negative ones. This ISH method for the detection of expression of the hTERT mRNA component may be an ancillary test for early recognition of cancer cells in body fluids and thus has potential as a diagnostic adjunct in cytopathology.