A subset of gestational trophoblastic disease characterized by abnormal chromosome 8 copy number detected by fluorescence in situ hybridization

The present paper describes the results of research conducted to ascertain whether the report by Mark et al. [1], describing the concurrence of congenital trisomy 8 mosaicism and gestational trophoblastic disease (GTD) in a 42 year-old Gravida IV, Para IV patient was an isolated event. In contrast to other cases described in the literature, the patient described in Mark et al. [1] had no additional confounding chromosomal abnormalities other than trisomy 8. To the best of our knowledge, ours was the only reported case of constitutional trisomy 8 mosaicism associated with gestational trophoblastic disease, a rare gynecological disease entity. The question arises whether there exists a subset of patients with GTD characterized by an abnormal chromosome 8 copy number. The implicit hypothesis is that an abnormal number of chromosome 8 somehow predisposes to cancer. A pilot study of 10 cases of GTD was conducted using fluorescence in situ hybridization (FISH) and a commercial chromosome 8-specific α-satellite probe on formalin-fixed, paraffin-embedded patient tissues. Among eight informative cases successfully completed, two cases (25%) were found to be trisomic, when a cut-off point of 10% trisomic cells is adopted. Another two cases (25%) were found to be triploid. The results of our FISH study indicated that an abnormal chromosome 8 copy number found in Mark et al. [1] is unlikely to be an isolated event. Our data are consistent with the hypothesis that a subset of GTD indeed may exist which is characterized by more than two copies of chromosome 8. The present findings corroborate those recently found in breast, prostate, and other cancers.