Variants of Yolk Sac Tumor

Abstract: In recent years, the clinical significance of certain variants of yolk sac tumor has become evident. To be considered a variant form, a yolk sac tumor must be composed predominantly or entirely of a single histologic pattern. Because of their rarity, their unusual histologic features, and the dissimilarity to typical yolk sac tumor, these variants may present diagnostic challenges. Some variants may occur predominantly in a single site, such as polyvesicular vitelline tumor in the ovary, or in a special clinical situation, such as the parietal or mesenchyme-like variants as recurrences of testicular yolk sac tumor after chemotherapy. The latter variants are unresponsive to the chemotherapy used for germ cell tumors, and therefore, the therapy is mainly operative. Other variants include solid, glandular, hepatoid, and those with secondary neoplasm. This review is largely confined to gonadal yolk sac tumors.