To investigate the clinicopathological characteristics, diagnosis and differential diagnosis of ovarian seromucinousborderline tumors (OSMBT), and review the related literature.

From 2005 to 2017, a total of 4 patients with OSMBT who underwent surgery at Beijing Shijingshan Hospital were selected as research subjects. The clinical data of the patients were collected by retrospective analysis method and the clinicopathological features, diagnosis of the patients were summarized. With the following keywords of " ovarian neoplasm" " seromucinous neoplasm" and " borderline neoplasm" both in Chinese and English, literature related to OSMBT were searched from Wanfang Data Knowledge Service Platform, China National Knowledge Infrastructure database and PubMed database, and literature retrieval time was set from January 1 of 2010 to January 31 of 2019. Clinicopathological features and diagnosis of OSMBT in searched literature were summarized. This study was in line with the requirement of World Medical Association of Helsinki revised in 2013.

①The results of 4 patients with OSMBT in this study were as follows. General clinical data: the patients′ age were from 29 to 65 years old, with a median age of 40 years old. The major clinical manifestations included abdominal pain and masses in pelvic cavity. The stages of International Federation of Gynecology and Obstetrics (FIGO) of 4 patients all were stage Ⅰ. Surgical methods: patient 1 and 2 underwent ovarian cystectomy, and patient 3 and 4 underwent hysterectomy and bilateral salpingo-oophorectomy. Appearance observation of surgically removed specimens: the tumors of 4 patients ranged in diameter from 0.9-10.0 cm, and the average diameter of these tumors was 4.4 cm. Patient 2 was bilateral OSMBT. The masses of tumors were described as unilocular cyst with papillary architecture in patient 1 to 3, and as solid in patient 4. Histopathological results of surgically removed specimens: the OSMBT tissues showed complex branched papillary architecture, without stromal invasion. Significant neutrophil infiltration was observed in the tumor epithelium, stroma of papillary architecture and glandular lumen of tumor gland. The lining epithelium was stratified and composed mostly of endocervical-type mucous, serous epithelium and hobnail cells with eosinophilic cytoplasm, and the nuclei were mild and moderately heterogeneous, and karyokinesis was rare. Patient 2 with bilateral OSMBT was combined with endometriosis. Immunohistochemisty results of surgically removed specimens: the immunophenotype of these tumor tissues exhibited CK7⁺ /PAX8⁺ /CK20^-/CDX2^-. Follow-up results: none OSMBT recurrence or metastasis was found in 15 to 156 months (average of 78.8 months) follow-up of all the 4 patients. ②The results of literature review were as follows. A total of 9 literature related with OSMBT were retrieved, involving 86 cases of OSMBT patients. The main clinical manifestations of them were abdominal distension, abdominal pain, abdominal discomfort, and so on. The median age of them was 49 years old. The average diameter of these tumors was 7.9 cm. Among them, 13 cases (19.1%, 13/68) were bilateral OSMBT, 30 cases (34.9%, 30/86) were accompanied with endometriosis, and 62 cases (91.2%, 62/86) were FIGO Ⅰstage. The average follow-up time was 35.9 months among 66 patients in 8 pieces of literature and the recurrence rate of OSMBT was 6.1% (4/66).

OSMBT is a kind of rare ovarian neoplasm and mainly associated with endometriosis. Most OSMBT patients are young. Histopathological detection results as well as immunohistochemical marker may help in pathologic diagnosis of OSMBT. Attention should be paid to the differential diagnosis from ovarian borderline serous, mucinous tumor and carcinoma before final diagnosis. Most patients with OSMBT are FIGO Ⅰ stage and have a good prognosis. Unilateral oophorectomy and follow-up closely could be a valid proposal in young patients who wish to preserve their fertility.