Background  

Extraovarian yolk sac tumors (YSTs) arising in the omentum represent an exceedingly rare malignancy.

Case  

A 37-year-old Korean woman was admitted with a history of lower abdominal pain of 3 weeks duration. Pelvic computerized tomography (CT) scanning reported a bilateral ovarian malignancy with peritoneal seeding. Exploration findings revealed a greater omental mass and the result of frozen biopsy was adenocarcinoma or mesothelioma. She was treated with supracolic omentectomy, bilateral salpingo-oophorectomy, pelvic and paraaortic lymph node dissection, multiple peritoneal biopsies and appendectomy. Histological evaluation of the specimen after operation exhibited typical patterns of YST and stained for alpha-fetoprotein (AFP) and cytokeratin. Four courses of bleomycin, etoposide, and cisplatin (BEP) combination chemotherapy repeated every 3 weeks were added to therapy and she has remained free of disease for 1 year after completion of the therapy.

Conclusion  

To our knowledge this is the fourth case of primary omental YST. A review of the literature indicates that the diagnosis of YST requires proper evaluations of tumor makers and a skilled pathologist for analysis of frozen sections.