[Differential diagnosis of tumors of the head and neck using immunohistologic and electron optic studies].

With indirect immunofluorescence microscopy it is possible to visualize intermediate-sized filaments which show a cell-specific distribution and in this manner establish a light-microscopical diagnosis in certain cases which are difficult or impossible to differentiate using conventional methods. We applied the same method to tumours of the head and neck region. Intermediate-sized filaments were studied in four malignant lymphomas, seven carcinomas and four metastases of carcinomas. Malignant lymphomas showed a positive reaction with antibodies to vimentin, carcinomas a positive reaction with antibodies to keratin. Using a monoclonal antibody against a single keratin polypeptide (cytokeratin 18) a further subdivision of the carcinomas was possible. The keratinizing squamous cell carcinoma and two non-keratinizing squamous cell carcinomas showed a positive reaction with the conventional antibody against keratin, but a negative reaction with the monoclonal antibody against cytokeratin 18. One adenocarcinoma, two anaplastic carcinomas and one lymphoepithelial carcinoma were positive with the conventional antibody against keratin and with the monoclonal antibody against cytokeratin 18. Thus lymphoepithelial carcinomas and anaplastic carcinomas should probably not be regarded as special variants of squamous cell carcinoma. In all metastases the same intermediate-sized filaments were demonstrable as in the primary tumour. Certain advantages of immunofluorescence microscopy when compared to diagnostic electron microscopy are discussed.