ficulties in defining specific subtypes of diffuse large B-cell lymphoma. Since the first recognition of certain large B-cell lymphomas in which the tumor cell content was dramatically outnumbered by reactive T cells or less often histiocytes, this descriptive term and related terms have been used to characterize a variety of lymphoma subtypes, and different studies have varied in the criteria used for this designation. To further complicate the issue, THRLBCL shares several morphological and immunophenotypic similarities with nodular lymphocyte-predominant Hodgkin’s lymphoma (NLPHL). Although the clinical presentation and behavior of these two diseases are generally quite distinct, some cases show overlapping features, suggesting a close biological relationship. The finding that both lymphomas may occur concurrently or subsequently in the same patient and/or families further supports the hypothesis that at least a subset is closely related. Finally, both NLPHL and THRLBCL may progress to more typical diffuse large B-cell lymphoma, once the neoplastic cells sheet out and the stroma is no longer the predominant component.