DEFINITION OF A NEW ENTITY OF MALIGNANT EXTRAGONADAL GERM-CELL TUMORS

Two malignant extragonadal germ cell tumors are reponed, histologicall y classified as immature teratomas, having pseudodiploid karyotypes wi th complex structural rearrangements but lacking isochromosome 12p or other rearrangements involving 12p. The absence of 12p material in str uctural rearrangements was confirmed by chromosome painting. In the tw o rumors the following common chromosomal breakpoints were found: 6p21 , 6p22, 6q23, and 11q13. Exactly the same chromosomal regions, 6p22::6 q23 and 6p21::11q13, were involved in fusions. The two tumors belong t o a new entity of extragonadal immature teratomas of adults which may be located in the retroperitoneum and posterior mediastinum and are pr one to blood borne metastasis. (C) 1995 Wiley-Liss, Inc.