Interphase fluorescence in situ hybridization for trisomy 12 on archival ovarian sex cord-stromal tumors.

Trisomy 12 is a nonrandom chromosomal abnormality found in a large proportion of ovarian sex cord-stromal tumors (OSCTs), including thecoma-fibromas (TFs) and granulosa cell tumors (GCTs). The prognostic significance of trisomy 12 in these tumors, however, is unknown. A series of 16 OSCTs, obtained from patients with long-term follow-up, was analyzed for the presence of trisomy 12 by interphase fluorescence in situ hybridization on paraffin-embedded sections. Sections of the contralateral nonneoplastic ovary were available in five cases and utilized as controls. Evidence of trisomy 12 was detected in 9 of 10 TFs, and contrary to previous reports, in only one of six GCTs. One TF with trisomy 12 was a malignant variant that resulted in the death of the patient in 5 months, but the remaining TFs with trisomy 12 were cytologically and clinically benign in those with follow-up available. The single GCT with trisomy 12 was a nonaggressive, stage 1 lesion without evidence of recurrence after 264 months, whereas those GCTs without trisomy 12 included one stage 2 tumor and a cytologically atypical GCT with tumor necrosis and an elevated number of mitotic figures. The evidence suggests that the great majority of OSCTs with trisomy 12 is clinically benign, but not all benign OSCTs have trisomy 12. We conclude that the presence of trisomy 12 is of limited prognostic usefulness in OSCTs.