The use of antikeratin antiserum as a diagnostic tool: thymoma versus lymphoma.

Indirect immunofluorescence staining in two thymomas, one case of thymic hyperplasia, 10 malignant lymphomas and three seminomas was done with an antibody prepared against keratins from human epidermis. Staining was observed only in the epithelial cells of the thymomas and thymic hyperplasia and correlated well with electron microscopic studies. Immunofluorescence staining of thymic tumors with antikeratin antibody provides a simple, specific, and sensitive method for distinguishing thymoma from lymphoma and seminoma. The method may also prove to be useful in other instances in the distinction between epithelial and nonepithelial tumors.