Mucinous Tumor Coexisting With Mesonephric-like Proliferation/Tumor in the Ovary: A Novel Association

The literature indicates that mesonephric carcinoma (MC) and mesonephric-like adenocarcinoma (MLA) typically lack mucinous and squamous features/differentiation. We report 4 cases of ovarian mucinous tumors (1 mucinous cystadenofibroma and 3 mucinous borderline tumors/atypical proliferative mucinous tumors [MBT/APMT]) co-existing with mesonephric-like lesions which were highlighted by Gata3 and Pax8 expression. All cases contained benign mesonephric-like proliferations (MLP) which focally displayed gastrointestinal-type mucinous metaplasia/differentiation and some were intimately admixed with mucinous glands associated with the mucinous tumor. Metaplastic mucinous epithelium retained expression of Gata3 and Pax8 in some areas while 1 mucinous cystadenofibroma and 1 MBT/APMT were focally positive for Pax8. Along with these mesonephric components, case 1 exhibited features of mesonephric hyperplasia and in 2 cases, 3 and 4, MLA was identified. In case 4, a KRAS c.35G>T (p.Gly12Val) somatic mutation was detected in both the MBT/APMT and the MLA, indicating a clonal origin. This same mutation was also detected in the benign MLP, indicating that it was likely an early genetic event. A CTNNB1 c.98C>T (p.Ser33Phe) somatic mutation, FGFR2 amplification, and CDKN2A/p16 deletion were only detected in the MLA but not in the MBT/APMT. Our result provides evidence to demonstrate the clonal relationship between these morphologically distinct components. Although speculative, we postulate that benign MLPs may give rise to lineage-specific mucinous and mesonephric-like lesions and propose that the MLPs are a new possible origin of some ovarian mucinous tumors. Whether these MLPs arise through transdifferentiation of Müllerian tissue or represent true mesonephric remnants, however, remains largely unknown.

A ruptured ovarian cystadenofibroma presenting with life-threatening sepsis and an incidental synchronous endometrial stromal sarcoma

A woman in her 60s presented with a rare complication of an ovarian cyst which many clinicians may not consider at first presentation. She was admitted with life-threatening staphylococcus aureus sepsis. She presented shocked with a collapse following a 2-day history of diarrhoea, vomiting and pain in the right iliac fossa. She was taken to theatre where a ruptured, widely infarcted left ovarian serous cystadenofibroma was discovered with over 2 litres of purulent fluid exuding from the cyst into the abdomen. She had a left cyst removal, hysterectomy and bilateral salpingo-oophorectomy performed. Histological analysis and molecular gene testing of an incidentally discovered uterine neoplasm revealed an undifferentiated uterine sarcoma. She successfully recovered as an inpatient and was discharged under the care of an oncology team for ongoing management.