Role of conventional cytology and cell block methods for diagnosis of malignant pleural effusions

Background: The study evaluates the role of a combined cytological smear (CS) and cell block (CB) approaches in malignant pleural effusion (MPE), highlighting specificity and sensitivity referred to histology and the incidence of different types of malignancies. Methods: We retrospectively included 223 patients over a duration of 5 years. Pleural fluid was collected and CS together with CB were made from the fluid. Immunocytochemical (ICC) stains were applied when requested by pathologist. Histology confirmation and medical records were recorded to confirm or not cytological diagnosis. Results: The combined approach demonstrated a diagnostic accuracy of 95%, 92% sensitivity, 96% specificity, positive predictive value of 92%, negative predictive value of 96%, positive likelihood ratio of 23 and negative likelihood ratio of 0.08. Lung cancer was found to be the commonest (23 cases, 33.8%) malignant neoplasm diagnosed in the pleurae followed by breast cancer (14 cases, 20.6%), gastrointestinal cancer (7 cases, 10.3%) and mesothelioma (6 cases, 8.8%). Conclusions: In our experience the combined approach definitively has proven to have an excellent diagnostic yield in the MPE, allowing to identify the nature of malignant cells in most of patients.