Hemophagocytic syndrome can be divided into primary and reactive, and the underlying disorders can be infections, tumors, immune-mediated diseases, etc. The destruction of blood cells is accelerated due to increased phagocytosis. Because the elderly are weaker and have poorer immunity so they are more likely to have infections, this disease is generally not contagious, if it is an infectious factor, the infectious factor should be removed as soon as possible, the primary disease can be treated well and then it can be cured by itself. Pathological features Benign histiocytes increase with hemophilia, mostly in the lymph sinuses and medullary cords of the lymph nodes, liver sinuses, portal veins, red marrow of the spleen and bone marrow. In the acute phase, the disease resembles leukemia, malignant histiocytosis, and infectious mononuclear cell hyperplasia, and hemophagocytosis is not found on the first bone puncture in all cases; sometimes multiple punctures are required to confirm the diagnosis. The bone marrow is mostly proliferating and the proportion of the granulocyte system is reduced, with toxic changes in neutrophils. The proliferation of the juvenile red system is mostly normal, and the proportion of the lymphatic system is not significantly changed. The mononuclear macrophage system is actively proliferating, often >10%, and the size of macrophages is 20-40 microns or larger, with abundant cytoplasm, engulfing multiple mature red blood cells, young red blood cells or platelets. Macrophages are approximately normal. Diagnostic criteria 1. fever: fever for more than 1 week with fever peaks >38.5°C; 2. hepatosplenomegaly: hepatosplenomegaly with whole blood cytopenia, cumulatively >= 2 cell lines; 3. hematocrit (peripheral blood secondary or blood tertiary cytopenia) with hemoglobin <90 g/L, platelets <100 x 109/L and neutrophils <1.0x109/L; 4. hypertriglyceridemia and/or hypofibrinogenemia; 5. Phagocytic cells are seen in the bone marrow, spleen or lymph nodes but without malignant manifestations. Infectious hemophagocytic syndrome is a benign hemophagocytic histiocytosis associated with acute viral infection, mostly in children, characterized by active monocyte-macrophage proliferation and marked phagocytosis of red blood cells. Patients tend to have marked hyperthermia and enlargement of the liver, spleen and lymph nodes, which mostly resolves spontaneously after treatment of the primary disease. Patients have anemia, a marked decrease in white blood cells, a marked increase in lymphocytes and a tendency to heterogeneous lymphocytes, and a decrease in platelets. The bone marrow is mostly proliferative, the proportion of granulocytes is reduced, and neutrophils are toxic. The proliferation of the juvenile red system was normal, and the proportion of the lymphatic system did not change significantly, and heterogeneous gonorrhea was seen. The mononuclear macrophage system is actively proliferating, often >10%, and the size of macrophages is 20-40 microns or larger, with abundant cytoplasm, engulfing multiple mature erythrocytes, juvenile erythrocytes or platelets. Macrophages are approximately normal.