3 Discussion

In this case report, two cases with ovarian cysts gradually increasing in size with gestational age were reported, both accompanied by the increase of one or more serum tumor markers. Surgery was conducted in case 1 and conservative management was used in case 2. Both cysts were finally identified as benign by clinical or pathological evidence. Currently, international consensus or guidelines regarding the management of ovarian tumors during pregnancy are still limited. Recently, a guideline on gynecologic cancers in pregnancy by European gynecologic oncologists was published ⁷, followed by a consensus on the management of ovarian masses during pregnancy by Chinese experts.⁹ But further discussions on diagnosis and treatment strategies are still needed for better individualized care of these ovarian cysts.

According to previous studies, ovarian masses were most commonly detected in the first trimester of pregnancy ¹⁰, possibly due to the advent of ultrasound during routine check-ups and the relatively higher frequency of torsion during this period.⁵ But sometimes they can be detected during caesarean sections or in the postpartum period.¹¹ Generally, ovarian masses during pregnancy will seldom cause severe clinical symptoms, unless complications like torsion or rupture occur.^5,12 Occasionally, large cysts may cause obstructive symptoms due to compression of the digestive tract or ureter, and may even be associated with labor obstruction.^5,12 Recently, Kiemtoré et al.⁴ reported a rare case manifesting as persistent abdominal distension after delivery, that was later demonstrated by surgery to be a serous ovarian cystadenoma of 42 cm in the long axis. In the two cases reported here, both patients were asymptomatic and the cysts were detected by ultrasound in the first trimester, which was similar to most cases reported before.^{11, 13}

The differential diagnosis of the cases included endometrioma, borderline tumor, and ovarian cancer. In a recent case series including 53 ovarian cysts suspected to be an endometrioma under ultrasound, 15 were monitored until the postpartum period, of which nine (60%) disappeared.¹³ In another study of 26 published cases, all eight cysts with conservative management resolved following delivery.¹⁴ In our report, one cyst also underwent spontaneous resolution during the late-pregnancy and postpartum period, but the other presented as an enlarging cyst. In the case series by Bailleux et al.,¹³ of the ten cysts surgically removed, only four were proved to be endometriomas by pathological examination, with the others being serous cystadenoma, mucinous cystadenoma, or dermoid cyst ¹³, indicating the difficulty of diagnosis during pregnancy. Decidualization of endometriomas, a relatively rare condition induced by high progesterone levels during pregnancy, further raised challenges to clinicians due to similarities to malignant tumors under ultrasound.^14–16 In studies analyzing ultrasonographic features of decidualized endometriomas during pregnancy, most cysts showed papillary projections, and rounded projections with vascularization was shown to be a vital feature,^16–18 consistent with our two cases. However, in an imaging study ¹⁶, only 22% of the cases showed more than three papillary projections in the cyst, while in our study, a multiple-papillary feature was seen in both cases.

Serum tumor markers provide very important clues for tumor properties. Nevertheless, some tumor markers like CA 125 and AFP could be elevated during pregnancy, especially in the first trimester ^19–21, making it difficult to accurately diagnose a malignancy. An earlier study conducted by Aslam et al.²² suggested CA 125 concentration of 112 U/ml to be a cut-off value for determining cyst properties in pregnant women. In our first case, only serum AFP was elevated, and in the second case, AFP, CA 125, and CA 19-9 all increased to different levels. Though CA 125 increased to 123.3 U/ml at 27⁺⁵ weeks in the second case, it then gradually decreased. Moreover, evidence from ultrasound and clinical manifestations further supported the diagnosis of a benign tumor. Therefore, the clinical significance of tumor markers should be determined based on the dynamic changes during pregnancy and in combination with other evidence.

In the recently published Chinese consensus for the management of ovarian cysts during pregnancy (9), for tumors 5–10 cm in diameter without evidence supporting malignancy, expectancy was recommended, and surgery indications included acute complications (including rupture and torsion), complication caused by obstruction (e.g. hydronephrosis), risk of birth canal obstruction, and strong evidence of malignancy. The recommended surgery time included 14–24 weeks of gestation, surgery during cesarean section, and 6 weeks postpartum. In the first case, imaging evidence including a relatively high speed of growth, multiple-papillary feature, and blood flow detected inside the cyst made it hard to completely exclude malignancy, though a higher probability of decidualized endometrioma was suggested, as mentioned above. A cystectomy during cesarean section was performed, though the tumor size was still below the 10 cm cutoff recommended by the consensus. For the second case, though multiple papillae and blood flow signals were observed, the relatively small diameter (<10 cm) and stabilization of tumor size in the third trimester helped us to determine that the cyst was not cancer, and a rapid regression observed during the follow-up after delivery further supported our assumption of the tumor as benign.

One strength of our study is that both cases were carefully monitored during gestation, making it feasible to notice any changes of the tumor and deliver treatment accordingly. Detailed ultrasound features of the two cases were studied, which may be helpful for future practice. But unfortunately, in the second case, pathological evidence to confirm our diagnosis was not obtained.