A mediastinal lymphoma with molecular, morphologic, immunophenotypic, and clinical features of both mediastinal (thymic) large B-cell lymphoma and classical Hodgkin lymphoma. The identification of this group of lymphomas, along with recent gene expression profiling results (PDL2 gene expression in both mediastinal (thymic) large B-cell lymphoma tissues and Hodgkin lymphoma cell lines), further supports the hypothesis that mediastinal (thymic) large B-cell lymphomas and classical Hodgkin lymphomas are related entities.