The role of concurrent determinations of pleural fluid and tissue carcinoembryonic antigen in the distinction of malignant mesothelioma from metastatic pleural malignancies.

A combined determination of pleural fluid and tissue carcinoembryonic antigen (PF-CEA and T-CEA) by radioimmunoassay and immunoperoxidase staining technique respectively was performed in patients with malignant mesotheliomas (12), metastatic pleural carcinomas (17) and benign pleural diseases (seven). All PF-CEA-positive (greater than 39 ng/ml) cases were T-CEA-positive metastatic carcinomas. In contrast, 4/30 PF-CEA-negative (less than 39 ng/ml) cases were T-CEA-positive metastatic carcinomas (three cases) and idiopathic pleuritis (one case). These results suggest that CEA, though present in the tumour, is not always released in measurable amounts in effusions. Hence T-CEA content should be determined in the PF-CEA-negative cases when an early and definite diagnosis of tumour type is required to enable correct management of these patients. These ancillary tests aim at enhancing the level of confidence of the routine morphological diagnosis of serous surface malignancies in living patients using minimal intervention instead of resorting to open chest surgery.