[Non-malignant cells in pleural fluid]

Insufficient attention has been paid to the cytological examination of cellular elements of the pleural fluid besides or in the absence of tumour cells. 108 cases studied due to pleural fluid were selected. They were characterized by the following: 1. each had histological diagnosis established by either pleuroscopy or by pleural needle biopsy and 2. neither of the samples contained tumour cells. Relationship of the dominant cell type and the ethiology of the pleural fluid was analysed. In case of punctates rich in lymphocytes further cytopathological differentiation is possible, e.g. in case of tuberculotic origin the absence of large mesothelial cells with Giemsa-basophilic cytoplasm is rather characteristic. The use of bioptic methods in the clarification of the origin of pleural fluid is still indispensible.