Diagnosis: Yolk Sac Tumor
• Yolk sac tumor can harbor clear cytoplasm in its cells, causing difficulty in distinguishing it from clear cell carcinoma in the differential diagnosis. Yolk sac tumor is more commonly seen in pediatric patients, whereas clear cell carcinoma is more commonly seen in older patients.
• Schiller-Duval bodies are seen in a few yolk sac tumors. One cannot rely on these structures to make the diagnosis. However, they are immensely helpful if they are present.
• The retiform variant of Sertoli-Leydig cell tumor and juvenile granulosa cell tumor are in the differential diagnosis of yolk sac tumor, and all three of these lesions occur in the same age group.
• The hepatoid variant of yolk sac tumor is characterized by polygonal, large epithelial cells that grow diffusely. There is abundant eosinophilic cytoplasm. The nucleus is central and contains a prominent central nucleolus. The appearance is similar to the liver—hence the name. It can occur in pure form or seen as a component of a mixed pattern yolk sac tumor.
• AFP is useful in distinguishing yolk sac tumor from other ovarian primary tumors because AFP staining is limited to germ cell tumors.