CTNNB1 p.L31P mutation in an ovarian endometrioid carcinoma with synchronous uterine endometrioid carcinoma

We performed next generation sequencing of DNA extracted from the neoplastic tissues obtained from a patient who underwent surgery for a large right ovarian carcinoma (OC) of endometrioid type associated with endometrial cancer (EC). This was done in order to ascertain whether the tumors were synchronous endometrial/ovarian cancers or an advanced metastatic stage from either the ovary or the uterus. Pathologic criteria favoured synchronous EC/OC. We identified a PTEN c.959 T > G (p.L320X) truncating mutation occurring with similar allele frequency in both neoplastic tissues (ovary: 88 %, endometrium 89 %) and a CTNNB1 c.100C > G (p.S37C) activating mutation, with a comparable allelic frequency in both tumor tissues (ovary 51 %, endometrium 52 %). The shared genetic mutations, and the presence of PTEN c.959 T > G (p.L320X) truncating mutation, albeit at low allelic frequency (6 %), in the healthy peritumoral endometrial tissue, appear to confirm the recent literature on a primary endometrial origin for synchronous EC/OC. A third mutation was CTNNB1 c.92 T > C (p.L31 P), a missense mutation occurring with a low allele frequency (3.7 %) only in the ovarian cancer tissue. This mutation is only occasionally described in hepatocellular carcinomas.