The Concept of Endodermal Sinus (Yolk Sac) Tumour

Abstract

The concept of origin and natural history of endodermal sinus tumours (yolk sac tumours) is reviewed. These tumours were recognized and defined on a comparative histogenetic‐embryologic basis as germ cell tumours with selective overgrowth of the extraembryonic endoderm and mesoblast of the yolk sac. The concept of endodermal sinus tumour has created solid and rational basis for the study of alpha‐fetoprotein reappearance in a formerly heterogeneous and confusing group of tumours, whether they occur in the adult or in infantile gonads, or in such extragonadal sites as the mediastinum, the sacrococcygeal region, the pineal gland, the retroperitoneum or the infant vagina. Alpha‐fetoprotein studies, in turn, have furnished new evidence in favour of the concept.