Hematologic diseases: These are diseases that occur in the hematopoietic system. Bone marrow, liver and spleen, and lymph nodes are all hematopoietic organs. 1. Bone marrow: contains hematopoietic stem cells, which produce red blood cells, white blood cells and platelets. When the hematopoietic function of bone marrow decreases (such as bone fibrosis), the liver and spleen compensate for hematopoiesis, causing hepatosplenomegaly. 3. Lymph nodes: they are hematopoietic and immune organs. In hematologic disorders, anemia or excess red blood cells, reduced or excessive white blood cells, and reduced or excessive platelets may occur. Blood disorders usually cause malaise, fever, bleeding, decreased resistance, bone pain, etc.