NK cell leukemia is a very rare malignant lymphoid tissue proliferative disease. It is characterized by a rapid onset of disease, usually accompanied by fever, jaundice, and coagulation abnormalities, and a rapid progression of the disease, with the possibility of multi-organ failure. Hemophagocytic syndrome is divided into familial hemophagocytic syndrome and secondary hemophagocytic syndrome, which is a histiocytosis with reactive proliferation of the mononuclear macrophage system. The mononuclear macrophage system is over-activated and proliferates, producing a large number of inflammatory cytokines, which are mainly manifested as persistent fever, splenomegaly, and pancytopenia, and may also be manifested by skin rashes, enlarged lymph nodes, and neurological symptoms. If you have the above symptoms, you should go to the hospital in time to find out the cause and take treatment under the guidance of the doctor.