GERM-02. IMMUNOHISTOCHEMICAL EVALUATION FOR THE PATHOGENESIS OF INTRACRANIAL GERM CELL TUMORS: EXPRESSION OF PLURIPOTENCY AND CELL DIFFERENTIATION MARKERS

Abstract

Abstract INTRODUCTION: Primary intracranial germ cell tumors (iGCT) are rare neoplasms that occur in children and adolescents. This study examined both the pathogenesis and the origin of these tumors, as it has been hypothesized that they originate from a totipotent primordial germ cell. MATERIALS AND METHODS: We applied recent knowledge from gonadal germ cell tumors and analyzed expression of a wide panel of stem cell-related proteins(C-KIT, OCT-3/4 (POU5F1), NANOG, SOX2, CD30 and PLAP). Expression shown by immunohistochemistry was analyzed in 12 children and young adults with iGCT, contributing to a careful description of these unusual tumors and adding to the understanding of pathogenesis. RESULTS: Immunohistochemistry showed 5/5 positive in Oct3/4, 5/5 in NANOG, 9/9 in C-KIT and 1/5 in SOX2. All cases that showed positive staining in Oct3/4 or NANOG indicated that the tumors contained germinoma or embryonal carcinoma component. Immunohistochemistry revealed that stem cell related proteins were highly expressed in iGCT, and many similarities were detected with their gonadal equivalents, including a close similarity with primordial germ cells. CONCLUSION: The expression of genes associated with embryonic stem cell pluripotency in CNS germ cell tumors strongly suggests that these tumors are derived from cells that retain, at least partially, an embryonic stem cell-like phenotype, which is a hallmark of primordial germ cells. In addition, these data can be applied to stratify iGCT for treatment strategy in order to provide good survival rate and good functional outcome.