[Tumoral markers and monoclonal antibodies]

The frequency of malignant pleuritis in general practice and its often difficult diagnosis have led to the ever increasing use of tumoral markers (TMs) which may overcome these difficulties and of immunocytochemical methods which may improve the results obtained by routine cytology. TMs are used in the diagnosis: a) to detect false-negative results and sometimes exclude false-positive results of cytology ("reactive" mesothelial cells); b) to distinguish reliably between malignant mesothelioma and metastatic pleuritis from an undetected adenocarcinoma, and c) to provide additional information, if needed, on the nature and origin of a malignant pleuritis. In pleural carcinology, TMs can be used as part of various methods which may be biochemical (assays of the marker in serum and, more important, in pleural fluid), cytochemical or immunocytochemical, histochemical or immunohistochemical, cytogenetic and cytofluorimetric. TMs can be defined and classified as follows: 1) intrinsic tumoral cell abnormalities; 2) substances associated with tumours which either induce them in the body without any specificity or secrete first generation TMs such as CEA, hyaluronic acid, NSE, ect.; 3) tumour-related antigens recognized by monoclonal antibodies or second generation markers. These markers, extremely varied, are directed against cell and often cell membrane antigens. They are not always very specific. When assayed separately their diagnostic sensitivity is low, but when used in batteries and combined with routine cytology they may fulfill the objectives listed above and fairly significantly improve the results of cytology. As last resort, they can be used in immunomorphology on cytology or biopsy specimens and provide a decisive answer.