Rapid transformation of low-grade endometrial stromal sarcoma to BCOR-rearranged high-grade endometrial stromal sarcoma in a patient with Birt-Hogg-Dubé syndrome: A case report.

This case report describes a 44-year-old woman with Birt-Hogg-Dubé syndrome whose FIGO stage IA low-grade endometrial stromal sarcoma rapidly recurred and transformed into BCOR-rearranged high-grade endometrial stromal sarcoma within six months. The authors asked whether such rapid high-grade transformation could be explained by tumor evolution, and comprehensive genomic profiling of the recurrence revealed a ZC3H7B-BCOR fusion and MDM2 amplification alongside a germline FLCN variant. Because molecular testing was not done on the primary tumor, the timing of the BCOR rearrangement could not be confirmed, but the findings suggest genomic profiling of recurrent disease may guide care and that MDM2 inhibitors could be a future option for selected patients.