Overview】Choriocarcinoma, referred to as choriocarcinoma, is a highly malignant tumor of trophoblastic cells. About 50% of the cases are secondary to gravidity, 25% are secondary to spontaneous abortion, more than 20% occur in normal pregnancy, and less than 5% occur in premature birth or ectopic pregnancy. This is because the trophoblast cells can remain hidden (in a non-proliferative state) for many years and then become active for unknown reasons. The main clinical manifestations are persistent irregular vaginal bleeding after gravida, miscarriage or full-term delivery, and significant increase of HCG concentration in blood and urine. before 1960s, the mortality rate of this disease was very high, but the improvement of chemotherapy regimen in recent years has greatly improved the prognosis of choriocarcinoma. Pathology】Choriocarcinoma mostly occurs in the uterus, but there are cases in which no primary lesion is found in the uterus but only metastases are present. To the naked eye, the uterus is irregularly enlarged and soft, with one or more purple-blue nodules visible on the surface. The tumor may be seen as a dark red, hemorrhagic necrotic mass filling the uterine cavity, or as a majority of nodules infiltrating the myometrium, often reaching the plasma membrane, causing a significant increase in uterine size, or as a diffuse polyp covering the endometrial surface, or with small foci of hemorrhage within the endometrium and myometrium. The tumor is characterized by dark red, brittle and soft hemorrhagic and necrotic lesions. Microscopically, patches of proliferating and poorly differentiated trophoblast cells are seen invading the myometrium and blood vessels. Cancerous thrombi are often found in the parametrial veins, and the tumor tissue consists of two types of poorly differentiated trophoblast cells, namely cytotrophoblast and syncytiotrophoblast. These two types of cells are disordered in their arrangement. The proportion of these two types of cells varies from tumor to tumor, with some being predominantly cytotrophoblast and others being predominantly syncytial trophoblast, and nuclear division is common. Choriocarcinoma tissue has no interstitium, often shows extensive hemorrhagic necrosis, and does not form a villous structure. If chorionic villi are found, even if they are degenerated, the diagnosis of erosive staphyloma should be made. Also the ovaries may form multicystic flavin cysts. Histologically, choriocarcinoma is very different from general carcinoma. Choriocarcinoma has no connective tissue mesenchymal cells inherent in general, only necrotic foci composed of trophoblasts, blood clots and coagulated necrotic tissue material, and no inherent blood vessels. The cancer cells are in direct contact with the blood of the host to obtain nutrition. Clinical manifestations】 1. Vaginal bleeding after delivery or abortion, especially after the clearance of gravida, there is irregular vaginal bleeding with variable amount. In a few cases where the primary foci have disappeared and there are only secondary foci, there is no vaginal bleeding and even symptoms such as amenorrhea. 2.Pseudopregnancy symptoms Due to the effect of HCG and estrogen and progesterone secreted by the tumor, the nipples and vulva are deepened in pigmentation, and the mucous membrane of vagina and cervix is also colored, and there are symptoms such as amenorrhea, breast enlargement and softening of reproductive tract. 3.Abdominal mass is due to the formation of hematoma in enlarged uterus or broad ligament, or enlarged flavin cyst, patients often complain of lower abdominal mass. 4.Abdominal pain is caused by cancer cells eroding the uterine wall or accumulation of blood in the uterine cavity, or due to cancer tissue penetrating the uterus or metastasis of internal organs. 5.The most common sites of metastasis manifestation are lung, vagina, brain, liver, gastrointestinal tract, etc. (1) Lung metastasis of choriocarcinoma is most frequent in the lung because of its hematogenous metastasis characteristics, which can produce different symptoms such as cough, bloody sputum and repeated hemoptysis depending on the metastatic site. (2) Vaginal metastasis is caused by retrograde flow of cancer cells to the vagina through the parametrial vein, and is second only to lung in incidence. It is characterized by purplish-red nodules protruding from the mucosal surface of the vagina as soft and substantial masses, which can cause massive bleeding or even fatal if the surface ruptures. (3) Brain metastasis is often secondary to lung metastasis and is the main cause of death. Early symptoms of transient cerebral ischemia appear, and if it continues to develop, it may cause bleeding in the subarachnoid space and nearby brain tissue, thus causing brain herniation, and the patient may die suddenly. (4) Liver, kidney and gastrointestinal metastases metastases are small and not ruptured and bleeding, so they are not easily detected, and if they rupture and bleed, they have symptoms of the corresponding organs.