Pathology of germ cell tumors in children

Abstract

Germ cell tumors may be defined as those tumors arising from a primitive germ cell. These tumors have the potential for differentiating along several disparate lines (Figure 1). l-3 The primitive germ cell may proliferate as a pure germ cell tumor, which is variously labeled as seminoma in the testis, dysgerminoma in the ovary, or germinoma in extragonadal sites. Alternatively, the totipotential primitive germ cell may develop as a benign mature teratoma, an immature teratoma of uncertain malignant potential, or a malignant tumor. In children, the malignant tumors are either pure germ cell tumors, embryonal carcinomas, or tumors manifesting extraembryonic features, such as yolk sac tumors and, occasionally, choriocarcinomas. Rarely, a teratoma may contain malignant neural elements. However, teratomas containing malignant epithelial components, such as seen in squamous cell carcinomas or adenocarcinomas, occur only in adults. In children, the malignant potential of malignant germ cell tumors is quite varied. Germinomas are the least aggressive, and teratomas with malignant neural elements (neuroblastoma) are the most aggressive forms of this tumor.4 Yolk sac tumors can usually be controlled by combination chemotherapy. Combination chemotherapy may also be effective in embryonal carcinomas in children, but the numbers are too small for statistical assessment.4.s