1. Case The patient is a female, 55 years old. She was admitted to the hospital with right epigastric stuffiness and discomfort for 1 year and pain for 1 month. Physical examination: T37.8℃, P94 beats/min, BP16/11kPa, no yellowing of the skin and sclera, limited elevation of the right upper abdomen, liver 4cm below the costal margins, palpation of the surface is not smooth, cystic, tenderness, no mobile turbid sounds. Laboratory tests: liver function was normal, HBSAg (-), AFP (-). ultrasound and CT showed a large hepatic cyst. Surgery showed that the liver was enlarged, the peritoneum was still intact, and the cyst was located in the right lobe of the liver, with a size of 32cmx21cmx20cm, with dark red fluid and necrotic tissues inside the cyst. After removing the tissues inside the cyst, the cyst and the right lobe of the liver were resected together, and the trauma of the liver was filled with the greater omentum. Pathological examination: The cystic mass was 26cmx18cmx10cm, with a slightly smooth, gray-red surface. A small amount of brown fluid and necrotic material remained in the capsule, and the inner wall was rough and uneven, gray and brittle, with a wall thickness of 1cm-3cm, and 6cmx3cmx1cm of liver tissue was attached to one side, which was adherent to the capsule wall. Microscopy: tumor cells spindle-shaped or epithelioid, spindle-shaped cells long spindle-shaped or slightly obese, tightly arranged, fenestrated and swirling, cytoplasm on one side of the slender fibrous filaments can be seen, nuclear anisotropy, schizophrenic >5/10HPF; epithelioid cells clustered or bundled arrangement, the cell class is round or polygonal, the cytoplasm is moderately eosinophilic, the nucleus is large and more deeply stained, the nucleolus is obvious, nuclei >6/10HPF, scattered tumor giant cells, mesenchymal edema and mucus degeneration, tumor tissue, the wall is rough and flat. mucinous degeneration, infiltrative growth of tumor tissue into the liver parenchyma. Reticulofibrillar staining: Reticulofibrillar fibers in the dense cellular area are long and straight, walking between the cells, and the fibers are close to the cell line but do not encircle the tumor cells. Immunohistochemistry: Vimentin (+), S-100 (+), Desmin (-), AFP (-). Pathologic diagnosis: primary giant malignant nerve sheath tumor of the liver; with hemorrhagic necrosis and cystic degeneration. Follow-up: recurrence at 1 year and 2 months, death at 1 year and 11 months. 3.Discussion Malignant nerve sheath tumor is also known as malignant nerve sheath tumor (MPNST), neurogenic sarcoma, undifferentiated neurofibroma and so on. They are mostly found in the head and neck, limbs and retroperitoneum, and their origin in the liver is rare. The origin can be Shewan’s cells, nerve underwear or nerve corset cells. The histology of this tumor has no clear features, often accompanied by hemorrhagic necrosis, cystic degeneration, interstitial mucous degeneration, the tumor cells have weaving, swirling or fenestrated arrangement, and the nuclear fission is easy to be seen, which should be paid attention to in pathological diagnosis, and when it is not easy to be distinguished from fibrosarcoma and smooth muscle sarcoma, it can be distinguished with the help of special staining or immunohistochemistry. The prognosis of this tumor is related to the degree of malignancy, local recurrence and metastasis are common, and the average survival is only about 44 months. 18 cases of 28 cases of malignant nerve sheath tumors in 2 groups reported by D′A-gostiono and White died from this tumor. Despite the long history of some cases, they are undoubtedly highly malignant in terms of clinical progression.