diffuse histiocytic lymphomadiffuse non hodgkin's lymphomadiffuse large cell lymphomadiffuse follicle center lymphomadiffuse b cell lymphoma treatmentdlbcl lymphomastage 4 diffuse b cell lymphomalarge cell non hodgkin's lymphomalarge cell lymphoma prognosisdlbcl non hodgkin's lymphomafallicular lymphomalymphoma organizations