Mucinous borderline ovarian tumor: a case report with diagnostic insights on ultrasound findings.

Borderline ovarian tumors represent about 10% of all epithelial ovarian cancers, but in contrast to epithelial ovarian cancers, they constitute a group of tumors with a much better prognosis. An assessment of clinical presentation, physical examination, radiological and biochemical findings is necessary to tailor management strategies for patients with ovarian tumors. The article, which is based on a case report, describes different approaches for preoperative diagnosis as well as discusses approaches that might bring some insights on tumor histology. Furthermore, it raises a question about which imaging techniques should be proposed for a reliable diagnosis of borderline ovarian tumors to ensure safe surgery planning.

Background

Between 70 and 75% of all ovarian tumors are of epithelial origin, with borderline ovarian tumors (BOTs) accounting for 10% of these neoplasms(. BOTs are defined as atypical proliferative tumors or tumors of low malignant potential with microinvasion into the stroma. There are seven types of BOTs: serous, mucinous, endometrioid, clear cell, Brenner, undifferentiated and mixed tumors. The incidence of BOTs among cysts without obvious signs of malignancy is low – about 0.6%(.

Although the diagnosis of BOT is based on histopathological examination, the preoperative evaluation of clinical, radiological and laboratory picture of the patient is of great importance. It is associated with a better prognosis than in the case of EOCs(. Accurate radiological findings related to the character of the lesion may play a crucial role in planning surgical treatment. This is also important due to the fact that the disease usually affects young women who wish to maintain their reproductive potential by undergoing a possibly less radical surgery(.

The aim of this article was to present a case of a patient with ovarian tumor in order to show the underestimated role of imaging techniques in the diagnostic process.

Case report

A 27-year-old woman with pelvic pain and abdominal discomfort presented to the Department of Gynecology, Gynecologic Oncology and Gynecologic Endocrinology in the Medical University of Gdańsk. She reported no cancer history or other hereditary risk factors. Abdominal examination revealed a palpable tumor mass that lifted the abdominal wall. No changes were observed in the morphology of the external genitalia. The body of the uterus was movable but shifted posteriorly by a mass adherent to the right ovary.

The CA 125 was over 600 U/mL. Transvaginal ultrasonography (TVU) of the lower pelvis showed an encapsulated, well-delineated structure mostly formed by a liquid content, measuring 12.2 × 3.3 × 5.2 cm, with a solid fraction present in its internal wall in the form of intraluminal exophytic papillary projections (Fig. 1). The cyst was probably connected with the right ovary, pushing the bladder backwards. The remaining pelvic and extrapelvic organs showed no abnormalities (Fig. 2).

Fig. 1

Ultrasound examination of mostly hypoechogenic multilocular cystic tumor with well-delineated smooth borders and a diameter of 12 cm, with small solid echogenic papillary projections (multi-locular solid type, however only one loculus is seen)

Fig. 2

Ultrasound examination: A. the same hypoechoic cystic tumor; B. there is a satellite tumor with a diameter of 3 cm of the same echostructure on the right

Cystoscopy revealed no lesions in the urinary bladder. Computed tomography (CT) confirmed the presence of cystic lesion with a solid fraction in the right ovary (Fig. 3).

Fig. 3

A. A contrast-enhanced CT scan showing no enhancement of the cystic portion of the tumor and mild wall enhancement with clearly visible large amount of exophytic papillary projections. B. Non-contrast-enhanced CT scan showing a cystic tumor with smooth margins and a diameter of 11 cm (30 H.u.) lying anteriorly to and above the bladder, slightly on the right

Laparotomy was selected as the surgical procedure due to the tumor size and the criteria for low risk malignancy. Right adnexectomy was performed. A cystic, multilocular tumor with a diameter of 11 cm that was adherent the omentum, peritoneum, urinary bladder and vesicouterine pouch was found. Other pelvic organs showed no pathological changes, including the left ovary.

Histologically, the tumor was described as a cystic tumor of the right ovary. The wall of the cyst was up to 1.5 cm thick, the internal surface was covered with wide intraluminal papillae up to 1.5 cm in height. Mucinous cystadenoma with limited malignancy of right ovary was diagnosed and staged IA/pT1aN0Mx according to the International Federation of Gynecology and Obstetrics (FIGO) and the American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) staging system.

Discussion

Ovarian cancer is the second most common gynecologic malignancy and the leading cause of death among women with gynecological cancers(. BOTs represent about 10% of EOC, but their prognosis is more favorable. These tumors are detected at younger age and at lower stages.

Difficulties arise at each level of evaluation. Imaging modalities play an important role in the diagnosis, staging and treatment in this subgroup of neoplasms, however, it is difficult to suggest a simple algorithm(. The choice of diagnostic modality mostly depends on the clinical context(. Ultrasound seems to be the first choice from the technical and economical point of view.

There are no specific radiological features selectively describing BOTs detectable by ultrasound or other, more advanced modalities. This makes the diagnostic process more difficult. US examination plays an important role in detecting and describing adnexal masses, with the TVU being of greater importance. It is not sufficient to evaluate tumor masses as precisely as recommended by the IOTA (International Ovarian Tumor Analysis)(. The questions that often arise are as follows: a) which algorithms to follow (images are only supportive) b) which course of action to take – operate or observe? Detailed evaluation provides different approaches: like IOTA’s terms or simple “tools” proposed by McDonald et al. who based their research on 3 types of adnexal masses plus/minus tumor marker elevation (solid vs. cystic vs. complex + CA 125)(. They found the combination of solid/complex mass with CA 125 elevation to be responsible for the identification of 77.3% of EOC cases. The problem is that there is no typical ultrasound picture of EOS or BOT. Gramellini et al. found BOTs in all 5 sonomorphological types of ovarian tumors. However, unilocular solid cysts which most commonly contained papillary projections predominated among all groups(. We observed a similar type of lesion in the described case. CT is not a routine procedure for the evaluation of adnexal masses. In our case, CT was performed for preoperative confirmation of BOT, however, it probably could have been avoided. MR imaging serves as a solving-problem examination(. Bent et al. described 4 categories of BOT appearances on MRI scans: 1) unilocular cysts; 2) minimally septated cysts with papillary projections; 3) markedly septated lesions with plaque-like excrescences and 4) predominantly solid lesions with exophytic papillary projections(. This research also described the most important clinical and imaging characteristics that could indicate a suspicion of BOT: in young woman with normal or mildly elevated CA 125 levels, showing predominantly cystic lesion at TVU examination with regular thin wall and the presence of normal ipsilateral ovarian stroma. Although the MRI findings did not differ from those derived from ultrasound studies, it allowed for a more objective and comprehensive evaluation of organs and disorders(.

Conclusions

Radiological assessment plays an important role in establishing the final diagnosis and treatment planning in patients with BOT. The role of a gynecologist is to make the final decision regarding further observation or surgery. The role of radiologist is to provide clinicians with assistance during the diagnostic progress, using available imaging modalities with ultrasound as the first choice.