Combination of Biochemical and Cytological Findings for Better Diagnosis in Pleural Effusions.

Serous pleural effusions result from increased permeability and changed hydrostatic or colloid osmotic pressure. Laboratory biochemical findings provide conclusions about the effusion compositions. Together with the anamnesis and clinical assessment, they enable the evaluation of the effusion nature. The present study retrospectively analyzed combined biochemical and morphological findings in 2307 effusions of patients from two clinical centers: LungenClinic Grosshansdorf in Germany and Duzce University in Turkey. The effusion cytology results of 1771 and 536 patients from the respective centers were combined with clinical/radiological/biochemical findings and counter compared with the final diagnoses. Cytology verified 738 malignant tumors (643 and 95, respectively). Most effusions were benign (n = 1569; 77%) and 367 of them were paramalignant (293 and 74, respectively) and 594 were inflammatory (465 and 129, respectively). There was a distinctly lower number of malignant tumors in transudates than exudates (87 vs. 725; p < 0.0001). Squamous cell carcinoma was more frequent in paramalignant pleura effusions (122 cases out of the 367 effusions) than pleural carcinomatosis (32 cases out of the 780 malignant tumors; p < 0.0001). The cell formula was a suitable marker for malignant mesothelioma, predominantly mesothelial, or neutrophilic characterized by elevated LDH (>500 U/L) in the early stage of empyema or its late manifestation. İn conclusion, most effusions are benign. Cytologists, assisted by clinical and biochemical data and microscopic findings, can make significant differential diagnostic contributions beyond the sole detection of malignancy.