Fluorescent in situ hybridization assessment of chromosome copy number in gestational trophoblastic disease

The concurrence of congenital trisomy 8 mosaicism and gestational trophoblastic disease in a forty-two-year-old Gravida IV, Para IV female has been described. In contrast to other cases in the literature, this patient had no additional confounding chromosomal abnormalities other than trisomy 8. To the best of our knowledge, this was the only reported case of constitutional trisomy 8 mosaicism associated with gestational trophoblastic disease, a rare gynecological disease entity in and by itself. The present report describes fluorescent in situ hybridization (FISH) studies for assessing chromosome 8 copy number on various patient tissues. The results of the FISH studies are compared with each other and with the original cytogenetic studies. It is concluded that the overall frequency of trisomy 8 cells is lower in the FISH studies using archival material than in the original conventional cytogenetic studies. This is true for the uterus and lung tissues with a metastatic tumor. The possible reasons for the somewhat different frequencies found between conventional cytogenetics via GTG-banding and interphase cytogenetics via FISH are discussed.