Evaluation of impact of immunocytochemical techniques in cytological diagnosis of neoplastic effusions.

A prospective study (1984-87) on the immunocytochemical identification of cancer cells in effusions using HMFG2 monoclonal antibody, and in addition, monoclonal anti-CEA and B72.3 antibodies in cases of suspected mesothelioma, was undertaken. On the basis of cytology alone, of a total of 2362 pleural, peritoneal, and pericardial effusions, 525 cases were diagnosed as positive and 1485 as negative for neoplastic cells, while in 352 (15%) specimens from 307 patients the diagnosis was doubtful. Sections of the embedded sediment of doubtful cases were tested with HMFG2 antibody and proved positive in 215 cases, negative in 108, and inconclusive in 29. The results were checked by following the clinical outcome of the cases. The method was specific in identifying cancer cells in cases at best diagnosed as suspicious on the basis of cytology alone; this represents a clear diagnostic gain. Sensitivity of the test, however, was relatively low (41%). Combined cytological and immunocytochemical characteristics (CEA negative and only some of the neoplastic cells positive with HMFG2 and B72.3 monoclonal antibodies) permitted diagnosis on the effusions of most cases of mesothelioma. The impact of the diagnosis on the progress of the disease was not appreciable as no difference in outcome was noted, irrespective of whether cancer cells had been recognised. The occurrence of an effusion remains an ominous sign in most patients treated for cancer.