Evaluation of cytomorphological examination in the diagnosis of pleural effusion.

Cytological examination serves as a crucial diagnostic tool for pleural effusion, with its diagnostic efficacy influenced by variations in specimen processing and staining techniques. Cellular morphological analysis of pleural effusions was performed using Wright-Giemsa staining to assess its diagnostic accuracy and clinical utility in differentiating the various etiologies of exudative pleural effusion. A routine examination was conducted on 2305 cases of unexplained pleural effusion, followed by cellular classification and morphological analysis in 1376 cases identified as exudative effusion. Among the 479 patients with malignant tumors, cytomorphological examination identified malignant cells in 295 patients, resulting in a clinical diagnosis coincidence rate of 98.6%. Abnormal cells, including malignant and heterogeneous nuclear cells, were observed in 364 cases, yielding a detection rate of 76.0%. The proportion of positive malignant cells in the newly diagnosed patient group was significantly higher than that in the previously diagnosed group (P < 0.01). Cytological analysis revealed the presence of bacteria, fungi, and phagocytes in 51 out of 1376 cases. The positivity rate for multiple bacterial infections detected through cytology was significantly greater than that identified by culture (P < 0.01). Additionally, various special morphologies and pathogens, which are rare in clinical practice, were detected, including mixed metastasis of small cell lung carcinoma and adenocarcinoma cells, as well as concurrent infections with Talaromyces marneffei and Pneumocystis jirovecii. This method enables the rapid and comprehensive differentiation between malignant tumors, tuberculosis, pneumonia, and rare exudative pleural effusions resulting from specific clinical conditions.