Metastatic thymoma: a case report and immunohistological analysis.

A patient with metastatic lymphocyte predominant thymoma was studied and an immunohistological analysis of frozen and paraffin sections was performed. The immunophenotype of the lymphoid cells was similar to that of primary thymomas and T cell lymphoblastic lymphomas. The epithelial cells reacted with an anticytokeratin monoclonal antibody. The results have diagnostic implications for the histopathologist using immunohistochemistry as a diagnostic aid and it is concluded that a panel of monoclonal antibodies against both lymphoid and epithelial markers should be used for immunohistological typing of tumours of uncertain histogenesis.