Almost one third of all patients diagnosed with BOT are aged under 40 years and the preservation of fertility plays an important role in therapeutic decisions [7]. Fertility-sparing surgical approach - defined as the conservation of the uterus and at least parts of one ovary – combined with a proper surgical staging has become therapeutic standard for the management of BOT in young patients over the past years [4, 5].
BOT represent a histopathologically heterogenous group of ovarian masses that are both, from clinical and subjective diagnostic criteria, difficult to determine [1]. In vaginal ultrasound, only one to two thirds of all cases are adequately diagnosed prior to surgery [8]. Definite diagnosis necessitates histopathological evaluation but frozen section analysis serves as important decision-making tool for further intraoperative procedures in this context [5].
eBOT in particular, represent a rare subtype of BOT challenging to be histopathologically distinguished from metastases of gastrointestinal, endocervical or endometrial adenocarcinomas as they show comparable immunohistochemical characteristics [1]. Previous studies reported on up to half of all cases of patients with eBOT having concomitant disorders of the endometrium and occasionally even synchronous endometrioid adenocarcinoma of the uterus, especially in younger and nulliparous patients [9, 10]. Endometriosis cysts, endometrioid adenofibroma and, in particular, deep infiltrating endometriosis with epithelial atypia are frequently associated with eBOT and appear as possible precursor lesions for the development of eBOT which then has potential to further progress to low-grade endometrioid carcinoma. While the differentiation between eBOT and endometrioid adenocarcinoma is not always straightforward, similar and foremost architectural criteria can be applied as to determine atypical hyperplasia from well-differentiated endometrioid adenocarcinoma of the uterine corpus [5, 10, 11].
Although a conservative surgical approach is associated with higher rates of recurrence in remaining ovarian tissue [12], fertility sparing surgery is considered to be oncologically safe as these recurrences are unlikely to undergo malignant transformation, estimated at only 0.5 % and still 2 % for advanced disease [3, 4]. Whether the histological subtype of the BOT should be taken into consideration for the surgical management, is still subject of discussion [3, 5]. Due to its low incidence, there is not much data on the oncological safety of fertility sparing surgery in patients diagnosed with eBOT, but previous studies have reported that invasive recurrences of eBOT may occur [6, 9]. While different research groups highlight the importance of uterine curettage and the need of an adequate follow-up in case of a fertility sparing therapeutic approach [1, 9], most international guidelines and treatment recommendations do not specifically address the importance to exclude an extraovarian primary in case of eBOT diagnosis when a fertility conserving approach is envisaged [5, 13-15].
Both presented cases in this report underwent surgical treatment after initial histologic diagnosis of an eBOT and were confronted with unexpected findings of invasive carcinomas of the uterus in histopathological evaluation. In the first case, dissemination of an endometrioid adenocarcinoma of the cervix uteri to the ovaries was initially misinterpreted as a bilateral eBOT at primary diagnosis. The second case was diagnosed with a contralateral invasive recurrence of an eBOT progressed to a well-differentiated endometrioid ovarian carcinoma and a synchronous endometrioid endometrial cancer in uterine curettage. Whether these two occurred as two independent synchronous carcinomas or whether there was an ovarian dissemination from the uterus could not be finally attributed.
Nonetheless, both cases clearly emphasize the indispensability of uterine diagnostics to exclude primary uterine neoplasm in case of eBOT diagnosis with an envisaged fertility sparing approach. Therefore, patients need to undergo uterine curettage when the uterus should be preserved to prevent possible underdiagnosis of a malignant primary tumor. This could result in wrong treatment decisions with a consecutive undertreatment from an oncologic perspective. Especially in patients designated to get pregnant, this might worsen the prognosis as there is a considerable risk for a delayed diagnosis of ovarian or uterine pathologies. Therefore, the requirement of uterine curettage as part of diagnostic workup to exclude endometrial pathology in case of eBOT with envisaged fertility preservation needs to be stated more prominent in treatment guidelines for young patients with BOT.