Immunohistologic diagnosis of multiple carcinomas. The role of monoclonal antibodies against carcinoembryonic antigen.

: The occurrence of multiple malignant lesions in the same patient requires that management decisions be made from an accurate pathological identification of the tumours. The authors describe five patients who had colorectal adenocarcinoma preceded or followed by adenocarcinomas in other organs. Definitive identification could not be established from routine histopathologic findings. The use of immunohistochemistry helped to clarify the relationship between the various tumours; in particular, a monoclonal antibody (D14) directed against carcinoembryonic antigen (CEA) made a notable contribution. Because of the increasing number of monoclonal antibodies with well-defined tumour specificities, their use in the documentation of multiple malignant tumours has great clinical potential.