100 patients with different types of pleurisy, hospitalized in the Bacau County Emergency Hospital, were investigated. The study was performed on pleural fluid from which pellets obtained from centrifugation, Gram stains, methylene blue and May-Grunwald-Giemsa staining, respectively, were performed. The following categories of cells were identified in the pleural fluid: reticulohistocytic elements (histocytes), blood elements (granulocytes, lymphocytes, and erythrocytes), mesothelial cells and tumor cells. Cell categories can be cytological formulas characteristic of different diseases based on they can be identified and confirmed. Thus, in serofibrinous pleurisy the picture of cellular elements does not presuppose the predominant existence of certain characteristic cell types, in T.B. pleurisy, numerous lymphocytes and enterocytes are characteristic, in hemorrhagic pleurisy, the large number of erythrocytes, in purulent pleurisy, the large number of granulocytes and lymphocytes, and in neoplastic forms, malignant cells.
