Characterization and Comparison of Ovarian Primitive Neuroectodermal Tumors and Immature Teratomas by Immunohistochemistry and Fluorescence In-Situ Hybridization
Nancy M Joseph, Martin P Powers, Charles J Zaloudek. UCSF, San Francisco
Background: Ovarian primitive neuroectodermal tumors (oPNETs) are rare germ cell tumors thought to arise from the immature neuroepithelium (imNE) of teratomas. Limited studies have been performed to characterize the immunohistochemical profile of oPNETs or their presumed imNE precursors. Although oPNETs are thought to mimic central PNETs (cPNETs) rather than peripheral PNETs (pPNETs), it remains unknown whether oPNETs exhibit MYC amplification as seen in cPNETs or EWSRI translocation as seen in pPNETs. Deletion of PTEN was also tested as PTEN deletion is known to promote primordial germ cell proliferation.
Design: Immunostains for markers of germ cell tumors (Sox2, Sall4, Oct-4), cPNETs (CD56, nestin, Bcl2, chromogranin, synaptophysin), and pPNETs (Fli-1, CD99) were performed in 5 oPNETs and 11 immature teratomas. FISH analysis for nMYC, cMYC, EWSR1, and PTEN was performed in all 16 tumors.
Results: Immunostain results are summarized in the table below. No oPNETs (0/5) or imNE (0/11) showed amplification for nMYC or cMYC or an EWSR1 translocation. 20% of oPNETs (1/5) but no imNE (0/8) showed PTEN deletion.