Histocyticsarcoma (HS) is a highly malignant tumor of the hematopoietic system that remains as a separate rare disease in the 2008 edition of the WHO Classification of Tumors of the Hematopoietic System under the broad category of histiocytic and dendritic cell tumors, defined as a malignant proliferation of histiocytes with a morphologic and immunophenotypic resemblance to mature histiocytes, expressing one or more histiocytic markers and not associated with acute monocytic leukemia. It was first named “histiocytic myeloid reticulocytosis” by Scott and Robb-smith in 1939 and further named “malignant histiocytosis” by Rappaport in 1966. ” malignant histiocytosis”, in 1970 Mathé et al. introduced the concept of “histiocytic sarcoma (HS)”, and in 2001 and 2008 WHO ( 2008) classification of hematopoietic and lymphoid tissue tumors finalized the nomenclature. There are still uncertain aspects of the pathogenesis of histiocytic sarcoma, and at present, because of the rarity of the disease, there are few studies on the mechanism, which may be related to many factors such as EBV infection and toxic exposure, as it has been generally accepted in academia that EBV is closely associated with non-Hodgkin’s lymphoma infection, and some studies have shown that L I II metastasis-related differentially expressed genes are associated with the metastatic aggressiveness of histiocytic sarcoma. The incidence of this disease is extremely low, <0.5% in non-Hodgkin's lymphoma, and most cases occur in adults, with a male prevalence and a median age of 46 years. The clinical manifestations are atypical: there may be adjacent metastases, the onset is insidious, the development is rapid, and the early stage patients have no obvious symptoms, and they are mostly found in advanced stages. It occurs in 1/3 in lymph nodes, 1/3 in skin, and 1/3 in other sites outside the nodes, such as spleen, bone and gastrointestinal tract. Histological features: The tumor cells are diffusely distributed, monomorphic or pleomorphic, with abundant cytoplasm and red phagocytosis. The tumor cells are large, round or ovoid, and some of them can be spindle-shaped. The nuclei are round or oval, may be multinucleated, vesicular nuclei, mild to moderate heterogeneity, and nucleoli are obvious. Immunohistochemistry: Tumor cells do not express T-cell and B-cell markers, Langerhans cell markers (CDla and langenn), dendritic cell markers (CD21 and CD35) and myeloid markers (myeloperoxidase), but express one or more histiocytic markers such as CD68 and lysozyme, and are characteristically strong positive for cytoplasmic granularity, lysozyme Golgi zone The lymphocyte gene rearrangements were generally absent. Lymphocyte gene rearrangement is generally absent with immunoglobulin and TCR gene rearrangement. The differential diagnosis varies between sites of morbidity and the final pathological diagnosis is clear. It should be noted that PET-CT is useful in the diagnosis, clinical staging and guiding treatment of this disease. The onset of the disease is insidious and progresses rapidly, and if surgical opportunities are available at the time of detection, surgical treatment is recommended. Chemotherapy is not sensitive and the commonly used chemotherapy regimen is CHOP (C: cyclophosphamide, H: doxorubicin, O: vincristine, P: prednisone), COPP regimen and MOPP regimen are also available as alternative more commonly used combination regimens, but still only some cases are in remission with any of them. Glucocorticoid monotherapy, radiotherapy and hematopoietic stem cell transplantation have been reported in the literature both at home and abroad, but the efficacy is not satisfactory.