Ovarian teratoma is a common ovarian germ cell tumor that originates from the primordial germ cells of the embryonic gonads and accounts for about 15% of all primary ovarian tumors, of which 95-98% are mature teratomas (i.e. benign teratomas) and only 2-5% are immature teratomas (malignant teratomas). Mature teratomas contain a variety of components, including skin, hair, teeth, bone, oil, and nerve tissue; immature teratomas are poorly differentiated, have little or no formed tissue, and are structurally indistinct. Clinical manifestations Mature teratoma can occur at any age, mostly between 20-40 years old. Most of the tumors have no obvious clinical symptoms when they are small, and most of them are found by chance during physical examination. When the tumor increases to medium size, abdominal distension is felt or a mass can be found in the abdomen with clear boundary. If the tumor grows to fill the pelvic and abdominal cavity, compression symptoms will appear, such as frequent urination, constipation, shortness of breath and palpitation. About 10% of patients have acute abdominal pain due to tumor rupture, torsion or bleeding. Immature teratoma is mostly seen in young patients with an average age of 11-19 years. Early stage is often asymptomatic, and the main symptoms in late stage are abdominal distension, abdominal mass, ascites and gastrointestinal symptoms. If the tumor infiltrates into the surrounding tissues or compresses the nerves, it may cause abdominal pain, lumbar pain or lower limb pain; if it compresses the pelvic veins, lower limb edema appears. In late stage, it may show cachexia, severe anemia and other cachectic symptoms. Clinical diagnosis ①Ultrasound examination: The diagnostic rate is high, and the clinical diagnosis rate is >90%, but it is not easy to detect solid tumors with diameter <25px, and it is possible to understand the location, size, morphology, cystic or solid mass, and whether there are papillae in the cyst. ②Abdominal radiography: it can show teeth, bone and calcified cyst wall. ③CT, MRI, PET examination: it can show the mass and the relationship between the mass and its surroundings, suggesting the presence of metastasis in other organs such as liver, lung or lymph nodes. 2.Tumor markers There are no specific tumor markers. It has been reported that the expression levels of CA125, CA199 and AFP in the blood of patients with immature teratoma are higher than those of patients with mature teratoma, but the sensitivity and specificity cannot reach the ideal level. Pathological examination Surgical pathological examination is the gold standard for diagnosis Treatment principles 1, mature teratoma Patients should choose surgical treatment. If the tumor is large and the normal ovarian tissues are small, it is not meaningful to preserve the normal ovarian tissues, so it is feasible to perform adnexal resection on the affected side; bilateral tumors strive to perform ovarian tumor resection; perimenopausal or postmenopausal women can consider performing total hysterectomy with both adnexa. The surgical method can be laparoscopic or open. 2.Immature teratoma ①Surgical treatment Complete staged surgery should be performed as far as possible. The pelvic cavity should be fully explored, the large omentum and peritoneum should be removed and lymph nodes should be biopsied to understand the scope of tumor infiltration and the degree of involvement of various organs and tissues. The basic principle of surgery is that regardless of the early or late stage, as long as the contralateral ovary and uterus are not cumulatively affected by the tumor, surgery to preserve the reproductive function can be performed by removing only the affected adnexa. In case of recurrent ovarian germ cell tumor, active surgery is still recommended. Chemotherapy is very sensitive to chemotherapy and the current WHO recommended chemotherapy regimen is BEP. Patients with well-differentiated stage Ia immature teratoma can be observed only after surgery, while the rest of patients should receive 3-4 cycles of chemotherapy after surgery. Follow-up Time: once a month for 1 year after surgery, once every 3 months for 2 years after surgery, once every 4-6 months for 3-5 years after surgery depending on the condition, and once a year after 5 years. Contents: clinical symptoms, signs, general and pelvic examination, ultrasound (MR or PET if necessary), tumor marker measurement, etc. Prognosis The recurrence rate of mature teratoma is about 2%, and the recurrence interval is more than 10 years, mostly seen in patients with bilateral lesions. The malignancy rate of mature teratoma is 2-3%. The recurrence rate of immature teratoma is higher (>50%), commonly within 2 years of diagnosis, but after recurrence immature teratoma has a characteristic transformation to maturity and gradually decreases in malignancy. At present, the survival rate of early stage patients over five years has reached 95-100%, and the efficacy of late stage recurrent tumors has also improved dramatically through chemotherapy and repeated and meticulous surgeries, which can reach 70-80%.