The degree of benignity and malignancy of teratoma mainly depends on the maturity of the tumor tissue, therefore, teratoma is divided into two categories: mature type and immature type. The majority of mature teratomas are cystic, called cystic teratomas, which are benign and mostly unilateral. It is most common among ovarian germ cell tumors, accounting for 97% to 99% of ovarian teratomas and 20% of all ovarian tumors. They occur mostly in women of childbearing age. Immature teratoma is less common and accounts for only 1% to 3% of ovarian teratomas. It is mostly seen in young patients under 25 years old. Pathology】 Mature teratoma is seen by the sarcoid eye, the tumor is mostly cystic, medium size, smooth surface, and the cyst contains hair mass and sebum-like material. The wall of the capsule is thick, and there is often a raised nodule or head node on the inner side, covered with squamous epithelium, and there are often hair, teeth or bone inside the nodule. Most of the tumors are single-compartment. On microscopic examination, various types of mature tissues of trichoblast can be seen, among which skin, sebaceous gland, sweat gland, hair follicle and fat are the most common; followed by cartilage, glial, nerve cells, bone and respiratory epithelium; others such as thyroid, gastrointestinal epithelium and teeth are less common. Cystic teratoma has a good prognosis, but a few of them may become malignant, and the most common one is squamous carcinoma. Malignant changes often occur near the cephalic nodes in the cystic wall, so attention should be paid to the sampling site during examination. The immature teratoma is mostly unilateral, generally large and nodular in size, and mostly solid in cut surface, interspersed with single or multiple cystic parts of different sizes. The solid part is often mottled, gray, brown or yellow, soft and brittle, often with hemorrhagic necrosis. Microscopic examination reveals a mixture of immature and mature tissues derived from trichoblast differentiation. The common immature tissues are neural tissues such as primitive neuroepithelium and ventricular canal membranes and various embryonic tissues such as embryonic bone, cartilage and muscle. Skin tissues are less common than the mature type. Some mature tissues of various germ layers may be mixed with them. Immature teratomas are often combined with other germ cell tumors, such as endodermal sinus tumors, asexual cell tumors, and choriocarcinoma. In general, the amount of immature and embryonic tissues in the tumor tissue correlates with the degree of clinical malignancy. According to the content of immature tissues, it can be classified into 3 grades: ①Grade I: mainly mature tissues, a small amount of immature tissues, no neuroepithelium or no more than one high magnification field in each slice; ②Grade II: more immature tissues, no more than one to three high magnification fields in each slice; ③Grade III: more immature tissues, more than four high magnification fields in each slice. high magnification field of view. Benign mature teratoma itself does not cause symptoms, but with the increase of the tumor, it may cause clinical manifestations such as abdominal pain due to compression, pulling or occupancy. In the case of malignant ovarian teratoma, menstrual changes may occur due to destruction of ovarian function, and symptoms of ascites, gastrointestinal tract and metastasis may also appear. Diagnosis】According to the condition, clinical manifestations, physical examination and auxiliary examinations such as ultrasound, a preliminary diagnosis of teratoma can generally be made. Since hair and bone are commonly found in mature teratoma, ultrasound and X-ray examination have corresponding specific signs, which are helpful for preoperative diagnosis. However, the specific nature of the lesion should be determined by the postoperative pathological diagnosis. Treatment】Once the teratoma is diagnosed, early surgery is necessary to avoid malignant transformation of benign teratoma due to delayed surgery and to prevent tumor infection, rupture, bleeding and complications. The main point of surgery for teratoma is to remove the tumor completely. The surgery must be delicate to completely separate and remove the teratoma, and the teratoma must not be allowed to rupture and contaminate the abdominal cavity during the operation. Currently, laparoscopic surgery has a wide field of view with magnification, which allows complete removal of teratoma tissue and does not easily contaminate the abdominal cavity. Although there are benign and malignant teratomas, malignant teratoma is different from other ovarian malignant tumors, because teratoma is formed by another embryo during fetal embryo development, and it does not belong to the patient’s own tissue. [Prognosis] Generally speaking, the prognosis of immature teratoma is poor. Surgery cannot guarantee complete and clean eradication of it, and there is a risk of recurrence. The prognosis of immature teratoma is closely related to the pathological grading and clinical stage. Recurrence and metastasis are mostly grade II and III. The sites of metastasis are mostly in the pelvis and abdominal cavity, and distant metastasis is extremely rare. In contrast, the prognosis of benign teratoma is better, and the possibility of malignancy in benign is only 2% to 3%. It does not affect ovarian function, normal menstruation and normal conception rate after surgery, and there is no problem of recurrence.