Abstract:

Objective To study the value of cell paraffin block immunohistochemistry and pleural fluid Crk like protein （CRKL） and macrophage inhibitory cytokine-1 （MIC-1） in the diagnosis of malignant pleural effusion. Methods A total of 98 patients with pleural effusion treated in Shantou Central Hospital from February 2020 to February 2021 were retrospectively selected as the research objects，including 58 benign cases and 40 malignant cases. The levels of CRKL and MIC-1 in pleural effusion were detected by enzyme-linked immunosorbent assay. The pleural effusion was analyzed by cell paraffin block immunohistochemistry. The levels of various indexes in benign group and malignant group were compared. The diagnostic value of cell paraffin block immunohistochemistry and pleural effusion CRKL and MIC-1 for benign and malignant pleural effusion was analyzed by receiver operating characteristic （ROC） curve. Results With pathological results as the gold standard，54 cases of benign and 44 cases of malignant were diagnosed by cell paraffin block immunohistochemistry. The diagnostic accuracy was 75.5% （74/98），and the sensitivity and specificity were 75.0% （30/40） and 75.9% （44/58） respectively. The levels of pleural effusion CRKL [2.84 （2.17，3.98） ng/ml vs. 1.88 （0.94，2.62） ng/ml]，MIC-1 [2.28 （1.67，2.98） ng/ml vs. 1.76 （1.22，2.32）] ng/ml] in the malignant group were higher than those in the benign group，with statistically significant differences （Z=-4.57，P<0.001； Z=-3.09，P<0.001）. The optimal critical value of CRKL in pleural effusion for the diagnosis of malignant pleural effusion was 2.33 ng/ml，the area under the curve （AUC） was 0.76 （95%CI： 0.66-0.85），and the sensitivity and specificity were 67.5% （27 /40），74.1% （43/58）. The optimal critical value of MIC-1 in pleural effusion for the diagnosis of malignant pleural effusion was 2.10 ng/ml，the AUC was 0.74 （95%CI： 0.64-0.85），and the sensitivity and specificity were 60.0% （24/40），82.8% （48/58）. The AUC of MIC-1 and CRKL in pleural effusion combined with cell paraffin block immunohistochemistry for the diagnosis of malignant pleural effusion was 0.83 （95%CI： 0.75-0.91），and the sensitivity and specificity were 85.0% （34/40） and 70.7% （41/58）. The sensitivity and AUC of combined diagnosis were significantly higher than those of CRKL and MIC-1 alone （sensitivity： χ²=4.26，P=0.046； χ²=6.27，P=0.012； AUC： Z=3.53，P<0.001； Z=4.14，P<0.001）. Conclusion CRKL and MIC-1 in pleural effusion of patients with malignant pleural effusion are highly expressed，which can be used as indicators for the diagnosis of malignant pleural effusion. Detection combined with cell paraffin block immunohistochemistry can improve the diagnostic value of malignant pleural effusion.

Key words: Pleural effusion, Benign and malignant, Crk like protein, Macrophage inhibitory cytokine-1, Cell paraffin block immunohistochemistry, Diagnostic value