A study on alpha-fetoprotein and endodermal sinus tumor.

The phenomenon of alpha-fetoprotein production by testicular, ovarian, or sacrococcygeal teratocarcinomas is frequently observed but has not been well explained. This paper includes clinicopathologic studies of 19 cases of teratocarcinoma with positive AFP reactions. Sixteen of the 19 showed typical histologic features of endodermal sinus tumor (yolk sac tumor) of Teilum and one other was compatible with this diagnosis.^6,7 The occurrence of AFP in these tumors is best explained by the concept of endodermal sinus tumor; because it is known that large amounts of AFP are synthesized not only by the fetal liver but also by the yolk sac during early embryonic life, and because the diagnosis of endodermal sinus tumor itself implies that the tumor is of yolk sac origin morphologically.¹³More direct evidence of AFP synthesis was demonstrated by immunofluorescent technique in one of our cases. Immunofluorescence was seen only in that cell layer long defined as of yolk sac origin morphologically.Alpha-fetoprotein studies are valuable in following such patients, unless they are 1 mo of age or younger.