General considerations Definition: A group of neoplastic diseases of lymphoid tissues Classification Hodgkin′ s Disease,HD ( Hodgkin′ s Lymphoma) Non Hodgkin / s Lymphoma, NHLDefinition：A group of neoplastic diseases of lymphoid tissues Classification： Hodgkin′s Disease, HD (Hodgkin′s Lymphoma) Non Hodgkin ′s Lymphoma,NHL) General considerations