Cytogenetic study of malignant ovarian germ cell tumors by chromosome in situ hybridization

Abstract

Scant cytogenetic data are available for ovarian malignant germ cell tumors (MOGCT) when compared with their testicular counterparts. The aim of this study was to analyze numeric and structural chromosome aberrations in MOGCT using the technique of chromosome in situ hybridization (CISH). Twenty- four cases, including six dysgerminomas, 12 yolk sac tumors (YST), and six immature teratomas (IMT) were included. Biotinylated probes specific for the pericentromeric regions of chromosomes 1, 11, 12, 16 and x and the short arm of chromosome 1 (1p) were used on formalin fixed paraffin embedded tumor tissues. All the dysgerminomas and YST showed increase in chromosome copy numbers of the chromosomes analyzed. Gain in chromosomes 1, 12 and 16 were found in all six dysgerminomas. YST showed gain in chromosome 1 (5 cases), chromosome 16 (9 cases), chromosome 12 (11 cases), chromosome 11 (11 cases) as well as chromosome x (8 cases). The hybridization signals for chromosome 12 in three dysgerminomas and four YST were found to be larger and/or smaller than those seen in normal cells suggesting the presence of i(12p). 1p deletion was found in one dysgerminoma and eight YST. In IMT, a gain in chromosome copy number was found only in the neuroepithelium, in chromosome 1 in two cases and chromosome 12 in another two cases. Our data demonstrates that CISH is a useful technique to identify the presence of multiple chromosome aberrations in MOGCT with different patterns seen in different histologic types. Such abnormalities may be important in the biology of these tumors and will be worth further analysis correlating karyotype with clinical behavior.