Demonstration of composite nodal B-cell lymphoma and subsequent Hodgkin's disease by flow cytometry and immunohistochemistry. Case report and review of the literature.

Hodgkin's disease has rarely been reported to occur subsequent to a previous non-Hodgkin's lymphoma, usually of B-cell type and with a 5 to 7-year median interval between diagnoses. Even rarer is the finding of residual non-Hodgkin's lymphoma at the time of Hodgkin's disease diagnosis. Six such cases have been reported, with five of the six representing "discordant" lymphomas and the other one a "composite" lymphoma. Only four of the six cases (all discordant lymphomas) were supported by immunohistochemical studies; flow cytometric immunophenotyping has not been performed in any of the reported cases. We report a nodal composite lymphoma (B-cell non-Hodgkin's lymphoma and Hodgkin's disease, mixed cellularity), supported by flow cytometric immunophenotyping and immunohistochemical studies, occurring in a patient 5 years after a diagnosis of B-cell non-Hodgkin's lymphoma. This report emphasizes the application and usefulness of flow cytometric immunophenotyping and immunohistochemical studies in such cases.