Proportion of the Malignancy Diagnosis Between Cytological Techniques Versus the Combination of Both Cell block and Cytological Techniques in Pleural Effusion

Abstract

Background: Pleural effusion is common in routine medical practice and can be due to many different underlying diseases. Thoracentesis is a diagnostic procedure for patients with pleural effusion. It is the most important investigation because of non-invasive and helps in faster reporting, especially when malignancy is suspected. The cytologic evaluation is performed on different specimen preparation techniques which include conventional smear, cytospin, and cell block preparations. Many studies support that the combination of conventional smear and cell block techniques can significantly increase the diagnostic yield for malignant pleural effusion as well as subtypes of malignancy.
Objective: To evaluate the proportion of the malignancy diagnosis between cytological techniques versus the combination of both cell block and cytological techniques in pleural effusion.
Methods: The study was a retrospective observational case-control study by collecting data on Thai patients who lived in Surin province with clinically suspected of malignant pleural effusion and underwent thoracentesis with pleural cytological evaluation in Surin Hospital from January 1^st 2022 to December 31^st 2022. Patient demographics and specimen characteristics were reviewed and evaluated by descriptive statistics. The proportions of malignancy diagnosis between cytological techniques versus the combination of both cell block and cytological techniques in pleural effusion were analyzed by inferential statistics using McNemar's Test. A p-value of <0.05 was considered statistically significant.
Results: The 601 cytological reports of pleural effusion were reviewed however 109 reports from 86 patients were submitted for evaluation. All patients with an average age of 64 years old showed pleural effusion with clinically suspected of malignancy. The cytological study was performed by two different techniques which were cytological techniques (CT) and the combination of both CT and Cell block preparation (CB). The concordant diagnoses of both techniques were identified in all the malignancies conversely, the borderline category was changed. The proportions of malignant had increased from 56.0% to 63.3% and the borderline had eased from 18.4% to 2.8% which showed statistically significant in all 3 categories at benign (P=0.002), borderline (P=0.000), and malignant (P=0.008). Moreover, the malignancy subtypes were identified, especially metastatic carcinoma (P=0.002) and metastatic adenocarcinoma (P=0.000)
Conclusion: The proportions of malignant pleural effusion showed a statistically significant increase by the combinations of CT and CB techniques compared to the use of the CT alone as well as the malignancy subtypes especially metastatic carcinoma and metastatic adenocarcinoma.