Patient LZZ, female, 24 years old, presented with the complaint of “vaginal bleeding for six months after normal delivery for one year”, after having delivered a baby girl at term one year ago. Six months ago, she had abnormal intermenstrual vaginal bleeding without any obvious cause, with low volume, dark red color, and mild abdominal pain, and went to the local hospital for ultrasound: blood in the uterine cavity, which was not treated. One month ago, she had vaginal bleeding again, and the ultrasound at the local hospital showed abnormal intrauterine echogenicity (35*17mm inhomogeneous echogenicity in the uterine cavity) and blood β-HCG: 50.55mIu/ml. 1 day ago, the ultrasound at the local hospital was repeated: intrauterine hyperechoic mass (45*40mm hyperechoic mass in the uterine cavity and posterior wall). She was then admitted to our hospital. After admission, Guo Ruixia of the Department of Obstetrics and Gynecology of the First Affiliated Hospital of Zhengzhou University showed abnormal intrauterine foveal echogenicity (52*42mm), poorly demarcated from the posterior wall muscular layer with abundant blood flow signal, localized thinning of the posterior wall muscular layer of the uterus, and pelvic varices (as shown below); blood β-HCG: 48.85mIu/ml. Preliminary diagnosis: abnormal echogenicity of the uterine cavity: 1. placental residue; 2. gestational trophoblastic tumor? The hysteroscopy showed that the cervical canal was normal in morphology, with abundant thick blood vessels on the surface and obvious bleeding, and the uterine cavity was probed, with normal morphology, dense blood vessels on the surface of the uterine cavity, bilateral tubal openings, localized elevation of the endometrium on the right side of the posterior wall of the uterus, and a small amount of grayish white pus-like tissue. The lesion was located in the muscular layer, and the area was densely covered with a thick vascular network, and bleeding was obvious. Intraoperative excised tissue was sent to pathology: (uterine contents) combined with HE and immunohistochemistry, consistent with placental site trophoblastic tumor, immunohistochemistry: CK(+), ER(-), PR(-), B-HCG(foci +), Ki-67 (about 40%), SMA(-), HPL(+), PLAP(-/+), P53(+), confirmed the diagnosis: placental site trophoblastic tumor In young women, if the lesion is confined to the uterus and the ovaries are normal, the ovaries can be preserved, and patients with high-risk factors should be given chemotherapy after surgery. We performed laparoscopic total hysterectomy under general anesthesia. Intraoperative dissection of the uterus revealed a focal area of about 100px on the left side of the posterior wall of the uterus, which was honeycombed and infiltrated the entire uterus. The postoperative recovery was good with 3 times of chemotherapy on the follow-up EMA-CO regimen. No recurrence at follow-up to date. Clinical features Placental site trophoblastic tumor (PSTT) is a specific type of trophoblastic tumor originating from the placental implantation site. It is rare clinically, accounting for about 1-2% of gestational trophoblastic tumors, most of which do not metastasize and have a good prognosis. Most of them do not metastasize and have a good prognosis. About 10%-15% of them develop metastatic lesions and are called malignant PSTT, with a mortality rate of about 20%. PSTT is mostly associated with pregnancy, often secondary to miscarriage, induction of labor, gravidity and full-term delivery, but rarely occurs during delivery. 2. Clinical manifestations PSTT occurs mostly in the reproductive age, but rarely after menopause, with an average age of 31-35 years, with a minimum age of 19 years and a maximum age of 50 years, mostly in menstruating mothers. According to statistics, 60% of the cases are secondary to full-term delivery, 25% are secondary to miscarriage, 13. 6% are secondary to gravidity, and occasionally combined with live births, and the symptoms are mostly irregular vaginal bleeding after amenorrhea or excessive menstruation, foamy urine, and physical signs of homogeneous or irregular enlargement of the uterus. Most of the lesions are confined to the uterus, and the prognosis is good. About 10% of patients will have metastasis, with the lung being the most common site of metastasis, followed by the liver, pelvis, vagina, gastrointestinal tract, and brain. Once metastasis occurs, the prognosis is poor. 3. Diagnosis PSTT symptoms and signs are atypical, the diagnosis needs to be combined with clinical manifestations and serological, imaging and pathological examinations, and the diagnosis mainly relies on pathological examinations. In most cases, the hysteroscopic biopsy can be used. The tumor surface is yellowish brown or yellow. Microscopically, the tumor is almost completely composed of intermediate trophoblast cells without villous structure. Immunohistochemistry: positive for HCG and HPL. As in the present case, the gross specimen showed a focal area of about 100px on the left side of the posterior uterine wall, yellow, honeycombed and infiltrating the whole uterus. The patient’s blood HCG was mildly elevated, and ultrasound showed an enlarged uterus with abundant blood flow signals.4. Treatment and follow-up Surgery is the preferred treatment option, and the principle is to remove all lesions and perform total hysterectomy and bilateral adnexal resection. In young women, if the lesion is confined to the uterus and the ovaries are normal in appearance, the ovaries should be preserved, or if the patient has no surviving children and still has fertility requirements, only the lesion can be removed. Patients with PSTT with high-risk factors should be treated with adjuvant chemotherapy after surgery. Most scholars believe that the preferred regimen is EMA-CO, and postoperative adjuvant chemotherapy is generally not advocated for patients without high-risk factors. Current studies suggest that the high-risk factors leading to PSTT are: (i) onset >2 years from the last pregnancy; (ii) nuclear schwannoma >5/10 HP; (iii); late International Federation of Gynecology and Obstetrics (FIGO) staging of the tumor with ectopic metastasis; (iv) blood 7-hCG >1000 mIU/mL; (v) last pregnancy is full-term; (vi) age at onset >35 years; (vii) presence of hemorrhage and hemorrhagic necrosis with clear cell and vascular infiltration [6.7] should be followed up closely after the end of treatment. The first follow-up is 3 months after discharge, then every 6 months until 3 years, thereafter every year until 5 years, and then every 2 years, and during the follow-up period, strict contraception should be used, and pregnancy should be allowed only at the end of chemotherapy >12 months. In this case, the patient was young, with no significant abnormalities in the ovaries on visual inspection. Total hysterectomy and EMA-CO adjuvant chemotherapy were performed with definite efficacy, and the post-treatment review was good. The common trophoblastic tumors mainly refer to erosive staphyloma (malignant staphyloma) and choriocarcinoma, which are different from PSTT in terms of clinical features and treatment, the former often has a very significant HCG elevation and is treated mainly with chemotherapy, while PSTT has a mild HCG elevation and is treated mainly with surgery.