Cytomorphologic concomitant reactions in malignant pleural effusions

This study was undertaken to establish whether there might be certain cytological findings in the pleural effusions which, with a high degree of possibility, point to the presence of a malignant process despite the absence of tumour cells. In tumour cell-containing effusions we found LE cells in 26.5%, and psammoma bodies in 31.9% of the cases. In non-tumour cell-containing effusions with, nevertheless, malignant genesis, we detected LE cells in 12.5% and psammoma bodies in 0.8% of the cases. In three out of 6 rheumatogenic effusions, LE cells were also found. Otherwise, neither LE cells nor psammoma bodies were to be seen in any of the benign effusions (74 cases). Furthermore, in all the malignant pleural effusions, extremely atypical mesothelial cells were always detected, the identification and description of which proved difficult.