Use of targeted therapy and immunotherapy for the treatment of yolk sac tumors in extragonadal pelvic sites: two case reports.

We present the clinicopathologic features and treatments of two cases of extragonadal yolk sac tumor (EGYST) detected in young females, including one in the myometrium admitted in 2013 and another in the serosal layer of the anterior wall of uterus admitted in 2019. The following details were recorded: patient age, clinical presentation, tumor location, International Federation of Gynecology and Obstetrics (FIGO) stage (where applicable), histologic patterns including Schiller-Duval (SD) bodies, other germ cell or somatic components, immunoperoxidase results, treatment, and outcome. The patients were aged 18 and 32 years old, both displayed the clinical manifestation of pain in the lower abdomen, tumor sizes were 10 and 8 cm, respectively, and alpha-fetoprotein (AFP) was significantly increased (1,210-20,251.0 ng/mL). Both participants underwent surgery and typical SD bodies were observed in postoperative pathology. Immunohistochemistry (IHC) results indicated that they were AFP positive (+) and Sal-like protein 4 (SALL4) (+). Both patients received multi-line chemotherapy after surgery, and participant 2 received targeted therapy and immunotherapy. At 36 months after surgery, one patient died, and the other was still receiving treatment. The benefit of germ cell appropriate chemotherapy in somatically derived EGYST has not been fully elucidated. Our report first showed that it is possible to reduce the recurrence rate and improve the prognosis of patients with EGYST by adding targeted therapy and immunotherapy (bevacizumab + tislelizumab) to traditional chemotherapy regimens.