The differential diagnosis of routinely processed anaplastic tumors using monoclonal antibodies.

The value of immunohistological labeling with a panel of monoclonal antibodies in the diagnosis of routinely processed surgical biopsies has been assessed. The cases examined consisted of an unselected series of tumor biopsies referred during a 12-month period because of doubt as to the nature of the neoplasm and are representative of the type of diagnostic problem regularly encountered in routine surgical pathology. In 30 of the 38 cases studied, reactivity with monoclonal antileukocyte antibody (and nonreactivity with monoclonal antiepithelial antibodies) indicated that the tumor was a lymphoma. Seven of the remaining eight cases gave the reverse reaction pattern and therefore were classified as carcinomas, while one biopsy was unreactive with all antibodies. Review of the clinical details in each case showed that the clinical management in several instances was influenced by establishing the correct diagnosis and it therefore is suggested that immunohistologic examination should be used more widely in the study of tumors that give rise to diagnostic difficulty.