Hemophagocytic lymphohistiocytosis (HLH) is a high-fatality disease caused by hereditary or acquired immune dysfunction, and is characterized by pathological inflammatory response. Primary HLH (pHLH) has hereditary genetic defects, and secondary HLH (sHLH) is caused by a variety of underlying diseases. Here, we report the case of a patient with aggressive natural killer cell leukemia and HLH-related gene defects who achieved long-term survival after treatment. A 20-year-old man presented to our hospital with symptoms of fever and fatigue. Investigations revealed splenomegaly, cytopenia, hyperferritinemia, hypofibrinogenemia, elevated levels of soluble CD25 (sCD25), and hemophagocytosis in bone marrow. Bone marrow flow cytometry showed 23.4% abnormal natural killer cells, the cells were CD2, CD7, CD16, CD94, NKG2A positive, met the diagnosis of aggressive NK-Cell leukemia. Investigation of the patient's pedigree revealed that mutations of pHLH-related genes (LYST and UNC13D) were inherited from his father and mother, but neither of the parents had the disease. The patient received hematopoietic stem-cell transplantation (HSCT), after which he achieved complete remission. As of 2020-10-19, the patient's survival has exceeded 3 years, and he has returned to his normal life. A variety of factors contribute to the onset of HLH, and this case gives greater insight into the etiology of HLH. Allogeneic HSCT is a key treatment for HLH patients with underlying genetic mutations.
Keywords: Hemophagocytic lymphohistiocytosis (HLH); aggressive NK-cell leukemia; hematopoietic stem-cell transplantation (HSCT).