Mixed Ovarian Neoplasms With Gastrointestinal-type Mucinous and Mullerian Epithelial Components: A Rare Group of Tumors Demonstrating the Phenotypic Plasticity of the Mullerian Epithelial Cell

Primary mucinous ovarian neoplasms, gastrointestinal-type (GI-type), are composed of mucin-producing tumor cells resembling intestinal goblet cells or gastric foveolar epithelium. In contrast to seromucinous tumors, which exhibit endocervical-type mucinous differentiation and are thought to be derived from endometriosis, the cell/tissue-of-origin of most GI-type mucinous ovarian tumors is unknown. We identified 8 GI-type mucinous ovarian tumors (cystadenomas, n=4; borderline tumor/carcinoma, n=4) with spatially distinct areas that showed morphologic features of Mullerian-type epithelial differentiation (ciliated cells or endometrioid-type glands). Immunohistochemistry for cell lineage markers and Alcian blue (pH 2.5)/Periodic Acid-Schiff staining were performed. Morphologically distinct components were isolated by microdissection, from which extracted DNA was analyzed by targeted next-generation sequencing. In all cases, immunohistochemistry demonstrated mucin-producing cells to be positive for at least one GI marker (CK20 or CDX2), while areas with morphologic features of Mullerian differentiation were positive for PAX8, ER and/or PR, and lacked expression of CK20 and CDX2; CK7 was strongly and diffusely positive in all tumor cells. Tumor cells with a gastric-type phenotype produced neutral mucin, while acidic mucin was present within intestinal-type goblet cells. Targeted sequencing revealed ARID1A mutations in all mixed borderline tumors/carcinomas (n=4); other recurrent genetic alterations included KRAS (n=2) and TP53 mutations (n=2). Shared mutations were present in paired Mullerian and GI-type mucinous tumor components in 4 mixed borderline tumors/carcinomas, with more shared mutations between components than private mutations specific to each component. All mixed borderline tumors/carcinomas were associated with endometriosis (n=3) or Mullerian inclusion cysts (n=1); mutation or loss of ARID1A expression was seen in these putative precursor lesions in 2 cases. Hence, ovarian neoplasms composed of clonally related GI-type mucinous and Mullerian-type epithelial components harbor ARID1A mutations and are frequently associated with endometriosis. The existence of a Mullerian stem/progenitor cell with the capacity to differentiate toward cell lineages within the GI-tract may be involved in the pathogenesis of at least a subset of GI-type mucinous ovarian neoplasms.

Ovarian torsion of mixed epithelial tumor misdiagnosed as a malignancy in postmenopausal woman: A case report

RATIONALE

Adnexal torsion is 1 of the most common emergency gynecological disease. It is more often diagnosed in reproductive age, but rarely in postmenopausal women. The clinical symptoms of adnexal torsion are nonspecific in postmenopausal women. Epithelial ovarian tumors are common in adults, and the risk of malignancy increases with age, especially after menopause. So, it is difficult to diagnose adnexal torsion precisely compared with reproductive women, and most cases of adnexal torsion with postmenopausal women are diagnosed as a malignancy preoperatively. We report a case of ovarian torsion with mixed epithelial tumor misdiagnosed as a malignancy in postmenopausal woman.

PATIENT CONCERNS

A 65-year-old woman presented lower left abdominal pain, and there was slight abdominal distension, but no tenderness or rebound tenderness on abdominal palpation.

DIAGNOSES

Radiologic assessments showed a huge multiseptated cystic mass with solid portion in the left ovary, and malignancy was suspected. The test for serum tumor markers revealed normal levels of cancer antigen 125 (CA-125).

INTERVENTIONS

The patient underwent a laparotomy and there was torsion of the left ovary. We conducted frozen biopsy of left ovary for confirming malignancy before performing staging surgery.

OUTCOMES

The result of a frozen section biopsy confirmed a borderline Brenner tumor associated with a benign mucinous tumor. Subsequently, total hysterectomy and right salpingo-oophorectomy were performed. The operation was completed without addition procedures LESSONS:: Ovarian torsion is benign in most cases and malignancy is rare. Although very rare, ovarian torsion can occur in postmenopausal women, and it should be taken into consideration that the possibility of malignancy is low in postmenopausal women with normal CA-125 levels. Instead of performing staging surgery, it appears to be appropriate to carry out surgery based on the result of intraoperative frozen section biopsy so that we were able to avoid unnecessary surgical procedures.