Immunohistopathologic study on carcinoembryonic antigen (CEA)‐like material and immunoglobulin a in gastric malignancies

Immunofluorescent staining for carcinoembryonic antigen (CEA)‐like material and immunoglobulin A (IgA) was performed on 54 gastric specimens showing normal mucosa and various lesions including malignancy. Both CEA‐like material and IgA were demonstrated in normal mucosa and benign and malignant epithelial lesions. Abnormal findings in respect of CEA‐like material included staining of cell membranes with disordered pattern and increased cytoplasmic staining. Several staining characteristics for CEA‐like material were shown by various types of malignant epithelial tumors. This staining provides a means of distinguishing anaplastic carcinoma from histiocytic lymphoma, as the latter does not demonstrate CEA‐like material. IgA was consistently absent in anaplastic carcinomas, but was noted on the inner surface of tubular components in the differentiated adenocarcinomas, indicating functional preservation in the differentiated tumors. Immunohistochemical staining for CEA‐like material and IgA is considered to be useful in the structural and functional study of gastric malignancies.