| Objectives The differential diagnosis between malignant and benign effusions depends on the results of laboratory tests, but no satisfactory ones are available so far. Recently some studies show that the telomerase activity assay is sensitive in the diagnosis of malignant effusions. However, the false positive rate is evident. In the present study, the expressions of telomerase reverse transcriptase (hTERT) mRNA and hTERT protein in the exfoliative cells of serous effusions were analyzed by in situ hybridization (ISH) and immunocytochemistry, respectively, and their values in diagnosis of malignant effusions were evaluated, and the causes of the false-positive mentioned above were identified. Methods Exfoliative cells in fresh specimens of serous cavity effusions were collected after centrifugation. Two cell smears were prepared for cytological diagnosis, by which the specimens were divided into benign and malignant and suspicious malignant effusion groups. The remaining cells were processed with a "standardized" procedure: removing red blood cells (when existing), fixed in 1% paraformaldehyde-PBS, and finally cell smears were prepared for ISH and immunocytochemistry. Three oligonucleotides labeled with digoxin were used as the probe of hTERT mRNA in ISH. In immunocytochemistry, the primary antibody was monoclonal rabbit anti-human hTERT, the second antibody was the biotinylated goat anti-rabbit IgG. The positive cells were determined by stained color density, and the positive specimens and their intensity were determined by the positive cell rates. The expressions of hTERT mRNA and hTERT protein and their diagnostic values were analyzed.Results A total of 94 specimens of serous cavity effusions were assayed, including 40 cases of malignant effusions and 43 cases of benign effusions and 11 cases of suspicious malignant effusions. Expressions of hTERT mRNA and hTERT protein were detected in 87.5% and 70.0% of malignant effusions, respectively, with most of them expressed strongly, and in 72.7% and 63.6% of suspicious malignant effusions, respectively, with most of them expressed stongly too, and in 25.6% and 37.2% of benign effusions, respectively, with most of them expressed weakly. The differences of positive rates and expression intensity of hTERT mRNA and hTERT protein were significant among three groups of effusions (P<0.05~0.005). Sensitivities of hTERT mRNA and hTERT protein in diagnosis of malignant effusions were 87.5% and 70.0%, specificities were 74.4% and 62.8%, positive predictive values were 76.1% and 63.6%, negative predictive values were 86.5% and 69.2%, diagnosis accordance rates were 80.7% and 66.3%, respectively. Combining analysis of hTERT mRNA and hTERT protein results: in a parallel way, sensitivity raised up to 95.0% but specificity was descent; in a series way, specificity raised up to 90.7%, but sensitivity was descent.The expressions of hTERT mRNA and hTERT protein in different kinds of exfoliative cells were obviously different: evident in malignant cells, most of them expressed strongly (77.0% and 56.5%); mild in reactive mesothelial cells, and most of them expressed weakly (25.8% and 27.8%); slight in lymphocytes, most of them expressed weakly (10.8% and 9.4%). The differences of hTERT mRNA and hTERT protein expression among three kinds of cells were significant (P<0.005). Conclusions1. hTERT mRNA ISH is positive in most malignant cells in serous cavity effusions, but negative in most benign cells, implicating that it is very valuable for the diagnosis of malignant effusions. 2. hTERT protein immunocytochemical staining is positive in most malignant cells in serous cavity effusions, but negative in most benign cells, implicating that it is valuable for the diagnosis of malignant effusions.3. The combination analysis of hTERT mRNA and hTERT protein can improve the sensitivity or specificity, and so a higher positive rate or reliability can be obtained in the diagnosis of malignant effusions.4. The expressions of hTERT mRNA and hTERT protein in reactive... |
