Branchial cleft cysts. Histologic and immunohistochemical aspects

8 cases of branchial cleft cysts and 1 case of branchiogenic carcinoma were examined immunohistochemically for detectable keratin, immunoglobulins (IgG, IgA, IgM), carcinoembryonic antigen (CEA), factor VIII related antigen (Factor VIII RGA), and lysozyme. Lectin binding patterns were also determined. Histologically, cystic lining epithelia were classified into stratified squamous epithelium without keratinization, columnar epithelium with or without cilia, or a mixture of both. Almost all of the cases indicated accompanying lymphoid structures with germinal centers. Keratin expression in epithelial cells was slightly positive, and lectin binding affinities in them were similar to those of oral squamous epithelium. CEA was found on the surface border of columnar epithelial cells, but cystic epithelia in most of the cases were devoid of lysozyme. Endothelial cells of capillary vessels showed positive binding by UEA-1 lectin and the presence of factor VIII RAG. In the lymphoid structures, there were scattered strongly positive lysozyme-staining cells as well as a few lymphocytes bearing IgG, IgA, or IgM.