Subversion of antigenic expression in neoplasia: lessons from immunohistology of teratomas

Many examples of inappropriate expression of intermediate filaments and other cell identity markers are known to occur in diagnostic tumor pathology. In the present study, this subversion of antigenic differentiation in tumors has been investigated using teratomas as a model, as these unique tumors not only mimic developing tissues but also show carcinomatous elements. Ten cases of teratoma (eight immature, two mature) were studied immunohistochemically using a panel of 13 commonly used cell identity markers, including intermediate filaments. Examples of antigenic coexpression and transbarrier expression in various morphologically mature and immature tissues were noted to be similar to those seen in various tumors. Carcinomatous elements in teratomas were non-reactive rather than showing antigenic aberrations. Hence, this study strengthens the proposition that antigenic subversion in neoplasia is related to the process of maturation and differentiation, rather than malignant transformation.