Uterine tumour resembling ovarian sex cord tumour (utrosct) associated with ctnnb1, pten and other gene mutations: Expanding the molecular landscape.

Uterine tumour resembling ovarian sex cord tumour (UTROSCT) is an uncommon neoplasm associated with recurrent gene fusions involving NCOA1-3, with ESR1 and GREB1 being the most frequent fusion partners. Fusions are not present in all cases and there have been few reports of gene mutations in these neoplasms. We report an index case of a UTROSCT (classic morphology with supportive immunophenotype) in a 58-year-old woman with no demonstrable fusions on RNA next generation sequencing (NGS) but with CTNNB1 and PTEN gene mutations. We reviewed a large series (n = 28) of UTROSCT from a single institution which had undergone RNA and DNA NGS. A total of 26 gene mutations were found in 12 of 28 (43%) cases, although no highly recurrent mutations were present. In 8 of these 12 cases, there were also characteristic gene fusions of UTROSCT. We stress that, especially in cases of UTROSCT with no fusions identified on RNA sequencing, it may be useful and informative to undertake DNA testing to look for underlying mutations.