Ovarian yolk sac tumor

　　The etiology of ovarian yolk sac tumor is not yet clear. Gross ovarian yolk sac tumors are almost always unilateral, with the right side being slightly more common; bilateral cases are mostly due to metastasis. Tumors are usually large in size, with a diameter often exceeding 10cm; they are round, oval, or lobulated, with a smooth surface and a capsule; sometimes they may adhere to or infiltrate surrounding tissues. The cut surface is mainly solid, with a powdery or grayish white color, moist and soft texture; often accompanied by cystic sieve-like areas containing jelly-like substances, which are honeycomb-like; hemorrhage and necrosis are common.
　　Microcystic teratoma has various histological structures under the microscope.
　　1. Microcystic structure:Also known as reticular structure, it is the most common. It is formed by flat or stellate tumor cells to create loose reticular and small or microcystic structures, under low magnification resembling a honeycomb (Figure 1), but under high magnification, the atypicality of tumor cells is obvious, and nuclear division is common.
　　2. Endodermal sinus-like structure:Also known as Schiller-Duval bodies. These are formed by cuboidal or columnar tumor cells arranged in a single layer, surrounding capillaries, thin-walled sinusoids, or small venous-like vessels, creating a vascular sheath-like structure, which in cross-section resembles a glomerulus. Although this special structure has diagnostic significance, in some tumors the morphology is not typical, and in the materials from Peking Union Medical College Hospital, only 54.2% show typical Schiller-Duval bodies.
　　3. Solid structure:Composed of small polygonal epithelioid cells aggregated together. The tumor cells have empty cytoplasm, large nuclei, and prominent nucleoli; nuclear division is active, similar to embryonal carcinoma.
　　4, Acinar structure:Also known as labyrinthine structure. Flat, cuboidal, or stellate tumor cells form tortuous and variable tubular or cystic structures.
　　5, Multilocular yolk sac structure:Flat, cuboidal, or low columnar tumor cells form cysts of different sizes, separated by dense spindle cell stroma or loose mucinous stroma. This structure is similar to the structure of the primary yolk sac transforming into the secondary yolk sac during the process of embryonic development.

　　The incidence of metastasis in ovarian yolk sac tumors is high. According to a survey data from Peking Union Medical College Hospital, 80% of patients who come to the hospital for treatment have already had metastasis. The vast majority are pelvic or abdominal peritoneal implantation, accounting for 93% of the metastasis, and 68% of the latter. Pelvic peritoneum includes the rectouterine pouch, vesical reflex, parietal peritoneum of the pelvis, serosal surface of the uterus, and surface of the opposite ovary, etc., and abdominal peritoneum includes omentum, peritoneum of the anterior and posterior abdominal walls, surface of the liver, and mesentery, etc. The routes of tumor metastasis include not only direct invasion and implantation spread, but also many through lymph node metastasis. The metastasis in the liver and lung parenchyma is less, but in some patients whose life span is slightly prolonged due to chemotherapy but ultimately unable to save them, sometimes liver and lung parenchymal metastasis can be seen.

　　Due to the rapid growth of ovarian yolk sac tumors and the ease of capsule rupture and intraperitoneal implantation, common symptoms include abdominal mass (76%), abdominal distension, abdominal pain (50%), and ascites (86%); tumor necrosis and hemorrhage can cause fever, with fever symptoms (50%); a few patients may also have breathlessness due to pleural effusion, but pleural effusion does not necessarily mean pleural metastasis; some disappear 10-14 days after surgery, and some cannot find metastasis in the thoracic organs at post-mortem examination, which seems to be a sign of Meige. The ovarian function of patients is generally normal, and a few patients have short-term amenorrhea or oligomenorrhea, and the fertility function before the disease is generally normal. Most married women have had pregnancy and childbirth, and some patients are found to have a pregnancy at the same time as the tumor is discovered. Due to the high malignancy and rapid progression of the disease, the time from the onset of symptoms to the time of seeking medical attention is very short, 45% does not exceed 3 months, and 64% does not exceed half a year.

　　The causes of ovarian yolk sac tumor occurrence are not clear, and there are currently no specific preventive measures. Regular screening of high-risk populations should be done to achieve early detection, early treatment, and follow-up work.

　　Ovarian yolk sac tumors have some characteristics in clinical manifestations, such as early onset age, large tumor size, easy to produce ascites, and rapid progression of the disease. If the possibility of this tumor is alerted, it is not difficult to diagnose. In particular, the detection of serum alpha-fetoprotein (AFP) can play a role in clear diagnosis. Yolk sac tumors can synthesize AFP, which is a very specific tumor marker. The radioimmunoassay method has a very high sensitivity for the determination of AFP in serum. Diagnostic tissue pathology examination is also required. Sometimes, the yolk sac tumor component in mixed germ cell tumors is very small, and it is necessary to make continuous sections or repeated sections to find tiny tumor lesions. There is an increase in AFP in serum.

　　Dietary precautions for ovarian yolk sac tumor patients:
　　1. Eat more foods with anti-ovarian tumor effects: horseshoe crab, sea horse, turtle, dragon pearl tea, hawthorn.
　　2. Hemorrhage should eat goat blood, snail, clam, cuttlefish, shepherd's purse, lotus root, mushroom, malan head, shi tou, hickory, persimmon cake.
　　3. Infection should eat eel, clam, water snake, needlefish, carp, kelp, celery, sesame, buckwheat, rapeseed, toon, red bean, mung bean.
　　4. Abdominal pain and distension should eat pork kidney, myrica, hawthorn, jujube candy, walnut, chestnut.
　　5. Avoid smoking, alcohol, coffee, cocoa, etc.
　　6. Avoid刺激性 food, such as scallion, garlic, ginger, chili, Sichuan pepper, cassia, etc.
　　7. Avoid moldy, charred food.
　　8. Avoid greasy, fried, grilled, smoked and other hot foods such as lamb, ham, smoked meat, and fatty meat.

　　Surgical treatment is the only method for the radical treatment of ovarian yolk sac tumor.
　　1. Surgical treatment for primary tumors:When ovarian yolk sac tumor patients seek medical attention, 50% to 80% already have extragonadal tumor metastasis. And the vast majority of metastases are localized to the surface of pelvic and abdominal visceral organs. Lymph nodes can also have metastatic tumors, which are often unilateral, so the surgical range should include the resection of the primary ovarian tumor, omentum, and intrapelvic implantation tumors.
　　Tumor cytoreduction surgery applied to ovarian epithelial cancer, which is to resect the tumor as thoroughly as possible, so that the residual tumor does not exceed 2 cm in diameter. Whether this tumor cytoreduction surgery is also applicable to ovarian yolk sac tumor, the surgical treatment principles for endodermal sinus tumor in the past were consistent with those for ovarian epithelial cancer. However, in recent years, since very effective and sensitive chemotherapy regimens have been found, it is still very necessary to resect the primary tumor and large metastatic foci. But if surgery will damage the integrity of the organs such as the uterus and rectum, as long as the large tumor can be removed, leaving a small amount of residual cancer tissue, chemotherapy after surgery is still effective, and it is not necessary to perform rectal resection or stoma to create an artificial anus. In short, surgery should not cause too much trauma to the patient. The small amount of residual cancer tissue can be eliminated by chemotherapy.
　　2. Surgical treatment for recurrent tumors:After the primary tumor of ovarian yolk sac tumor is resected, if effective combined chemotherapy is not carried out in a timely manner or the chemotherapy is insufficient, the tumor often recurs quickly. If the recurrent tumor is relatively localized and has a small volume, it may be effective to use combined chemotherapy alone. If the recurrent tumor in the abdominal cavity is widely distributed and numerous or has a large volume, surgical resection is still necessary to achieve a successful and satisfactory effect from combined chemotherapy.
　　3. Chemotherapy:The PVB [cisplatin P, vincristine (vincristine) V, bleomycin B] combined chemotherapy regimen has been very successful in treating widespread metastatic testicular cancer, so the PVB combined chemotherapy has quickly become a common chemotherapy regimen for ovarian malignant germ cell tumors. Regarding the successful experience in the treatment of refractory testicular cancer, there is also the BEP combined chemotherapy regimen B: bleomycin P: cisplatin, E: etoposide (VP-16), which has similar effects to PVB but lower toxicity (Williams 1987). There is no clear unified opinion on the number of treatment courses for the above medications. For stage I cancer or cases with metastasis but where the tumor mass can be completely resected, 3 to 4 courses are recommended. If the residual cancer after surgery is large, then 5 to 6 courses may be needed.
　　The PVB [cisplatin P, vinblastine (vincristine) V, bleomycin B] combined regimen, as long as special attention is paid to the medication 'timely' and 'adequate' during the medication process, the effect will be very satisfactory. There are a few cases where the tumor has not been surgically removed, but long-term continuous remission has been achieved, thus leading to the thought that whether the treatment of yolk sac tumors can be completely dependent on the effect of chemotherapy without the need for surgical resection. Although combined chemotherapy for ovarian yolk sac tumors can achieve very satisfactory results, most reports are on the auxiliary chemotherapy after the tumor is surgically removed. Only a few cases have achieved continuous remission with chemotherapy alone. There is insufficient evidence to support the use of chemotherapy alone instead of surgery and combined treatment. Moreover, the primary tumor of yolk sac tumors is generally large, and the necrotic tissue volume after chemotherapy is also large. Although it can be gradually absorbed by the body, the absorption of this necrotic tissue is still a burden on the patient, and it is possible to leave intra-abdominal adhesions. And the surgical treatment for yolk sac tumors does not emphasize the complete resection of tumor cells, as long as the main large tumor mass is removed, the surgery is not complex, and the trauma is not great. Attention should be paid to maintaining the integrity of the healthy ovary and uterus, so the surgical treatment is still an indispensable step. Relying solely on chemotherapy is bound to increase the number of treatment courses, and chemotherapy with cisplatin and bleomycin has certain toxicity. Excessive chemotherapy may impose a greater burden on patients compared to a relatively simple surgery, so it is still necessary to consider the comprehensive treatment of surgery and chemotherapy in principle.