Vulvar yolk sac tumor

　　1. Etiology

　　Vaginal yolk sac tumors are due to the lack of embryonic tissue conductors in the decisive period of germ cell migration, resulting in the mislocation of germ cells, some of which remain subcutaneous on the mons pubis or labia and abnormally differentiate.

　　2. Pathogenesis

　　The tumor presents as a brownish or grayish mass with a pseudocapsule. The cut surface shows both cystic and solid components, most of which are honeycomb-like microcysts and small cysts, filled with varying fluids such as watery fluid, serous blood, and thick fluid. The solid areas are necrotic and hemorrhagic with necrosis.

　　Microscopy shows a network of tubular spaces composed, with the lumen lined by endothelial cells. The cells are separated by irregular fibers, forming a nest-like structure, and many transparent small bodies with positive PAS staining in the cytoplasm and extracellular spaces are visible. The characteristic SD (Schiller-Duval) bodies formed by the vascular and radially arranged tumor cells are the main basis for diagnosis. The tumor tissue can present positive AFP expression, and some CEA positive.

　　Vaginal yolk sac tumors mostly occur in the large labia, also seen in the clitoris, manifested as painless, hard, mobile mass, which can also be manifested only as vulvar swelling. There may be tenderness, the surface skin may have ulceration or cellulitis-like changes. It is prone to ulceration and bleeding due to local friction, and with the decrease of the patient's resistance, pathogenic bacteria are easy to enter the body, resulting in secondary infection.

　　The course of the disease is short, generally 1 to 9 months, with rapid development, mostly occurring in the large labia, also seen in the clitoris, manifested as painless, hard, mobile mass, which can also be manifested only as vulvar swelling, with tenderness, the surface skin may have ulceration or cellulitis-like changes, the size of the mass is (1.2×1.5)cm to (10×6)cm.

　　1. Pay attention to regular physical examinations, detect early, treat in a timely manner, and do a good job of follow-up.

　　2. Epidemiology: Vaginal yolk sac tumor is one of the rare malignant tumors of the vulva, with an onset age of 1 to 26 years, with a median age of 18 years.

　　3. Prognosis: The general prognosis is poor. There are 2 cases of vaginal yolk sac tumors with a better prognosis, one occurring in a patient with the clitoris after 42 months of tumor-free survival following radical clitoridectomy. The other is a patient reported by Flanagan et al., who received chemotherapy with the BEP regimen after radical vulvectomy and unilateral superficial inguinal lymph node dissection. The bleomycin was stopped due to pulmonary fibrosis symptoms at the 5th week of chemotherapy, and etoposide (podophyllotoxin) and cisplatin were administered for 3 cycles. No recurrence was seen during the 18-month follow-up after chemotherapy.

　　The diagnosis of vulvar yolk sac tumors, in addition to clinical manifestations, also requires essential related examinations. The following are the examinations:

     1. Alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), secretion examination.

　　2. Histopathological examination.

　　1. Fever, prone to respiratory and urinary tract infections.

　　2. Long-term chronic intoxication can cause calcification of bones, kidneys, blood vessels, and skin, affecting physical and intellectual development.

　　3. High blood calcium and high urine calcium are prone to form kidney stones. Severe cases can lead to death due to renal failure.

　　4. Vitamin D intoxication in early pregnancy can cause hypercalcemia in the fetus, leading to congenital malformations.

　　Precautions before treatment of vulvar yolk sac tumors:

　　There are currently no very effective traditional Chinese medicine treatment methods and Chinese herbal medicine for vulvar yolk sac tumors. The treatment of vulvar yolk sac tumors with Western medicine must be actively adopted due to the high malignancy of yolk sac tumors, which quickly lead to lymph node and hematogenous metastasis after occurrence. Therefore, it is necessary to adopt surgery first and then辅以化疗. Flanagan et al. (1997) suggested using radical vulvar surgery to preserve fertility, because 2 out of 7 cases of vulvar yolk sac tumors had inguinal lymph node metastasis, and both patients died within a year, so it was proposed to routinely remove the inguinal lymph nodes.

　　Since the 1980s, the VAC (vincristine, actinomycin D, and cyclophosphamide) chemotherapy regimen has achieved good efficacy in the treatment of ovarian yolk sac tumors. However, vulvar yolk sac tumors are not very sensitive to the VAC regimen. Although 3 patients received VAC regimen chemotherapy after radical vulvar surgery, they all died within a year. Graighead et al. (1993) treated one case of vulvar yolk sac tumor with BEP regimen (bleomycin, etoposide, cisplatin) chemotherapy after surgical resection, but the patient was resistant to platinum drugs and developed inguinal lymph node metastasis 5 months after surgery, and the condition was controlled after inguinal external irradiation.