Decidualized endometriotic cyst: A report of two cases

Introduction Endometriosis, a benign but progressively debilitating disease, is defined as the presence of glands and stroma outside the uterine cavity. Symptoms can be mild to severely incapacitating. Several hypotheses explain the pathophysiology of the disease, but no single theory sufficiently describes all the symptoms. Some of these theories include genetic factors, presence of endometrial tissue outside the uterus through retrograde menstruation, aberrant endocrine signaling, and imbalanced cell proliferation and apoptosis. Retrograde menstruation, wherein endometrial tissues are carried backward and are implanted at ectopic sites, is the most widely accepted hypothesis. These endometriotic implants, most commonly located in the ovaries,[1] are identical to eutopic endometrium. They also contain estrogen and progesterone receptors that grow and respond to hormonal changes. Pregnancy affects the biological behavior of these ovarian endometriomas.[2] Majority decrease in size significantly because of induced apoptosis brought about by increased levels of progesterone and cessation of menstrual cycle. Around 12%[2] undergo decidualization, which is a physiological response of endometrial stromal cells in preparation for pregnancy. The elevated level of progesterone causes hypertrophy in the vascular decidual lining of the gravid uterus, but at the at the same, it affects other ectopic endometrial implantation sites as well like preexisting endometrial cysts. This phenomenon poses a diagnostic dilemma as it mimics a malignant tumor. Adnexal masses complicate 0.5%–1.2% of pregnancies and 11% of these are endometrial cysts.[3] Furthermore, decidualization of an endometrial cyst is a rare occurrence.[4] A unique appearance of pregnancy-related deciduosis is the development of a decidualized mass that sonographically resembles a malignant tumor. This report discusses two cases of decidualized endometrioma. On ultrasound, the first case had an impression of ovarian malignancy, while for the second case, a decidualized endometrioma was suspected. Case Reports We identified two cases of decidualized endometrial cyst in our institution. Case 1 A 26-year old gravida 1 para 0 had an incidental finding of left ovarian new growth at 13 weeks age of gestation (AOG) during her prenatal check up. She had no signs and symptoms and the finding was not present on a previous sonographic examination done 4 years before pregnancy. Pelvic ultrasound showed a single, live, intrauterine pregnancy at 13 weeks and 2 days by fetal biometry with good cardiac activity. The right ovary was normal in size and echotexture and the left ovary was enlarged to 13.6 cm × 6.1 cm × 10.6 cm, volume of 460 cc, and was described as multilocular-solid structure, thin-walled with thick septa, containing low to medium-level echoes with solid structures and papillary projections, moderate color flow, color score of 3 [Figure 1], suggestive of a malignant ovarian new growth. On further workup, serum cancer antigen (CA) 125 was elevated at 106.70 U/mL, and human epididymis protein 4 was normal at 19.7 pmol/L. The patient was counseled regarding the probability of an ovarian malignancy, therapeutic options were discussed, and she eventually chose to have a surgical intervention. She underwent peritoneal fluid sampling and left oophorectomy with infracolic omentectomy under combined spinal-epidural anesthesia. Intraoperatively, the left ovary was converted to a 12 cm × 11 cm × 10 cm, irregularly shaped, violaceous cystic mass with multiple locules and was twisted once at its base [Figure 2]. On cut section, the cyst contained dark chocolate brown to black fluid. On gross pathological inspection, the identifiable external surface was pink tan to brown tan, smooth, and glistening. The internal surface was yellow tan to brown tan, variegated, with firm area measuring 7 cm × 5.5 cm × 1.5 cm [Figure 3]. Microscopically, the internal lining of the left ovary was lined by an endometrium composed of columnar cells and an endometrial type of stroma with several cystic follicles seen undergoing maturation; omentum showed decidualized tissues with no definite endometrial lining and stroma were seen; peritoneal fluid had a strip and small clusters of mesothelial lining was observed with scattered inflammatory cells and singly scattered mesothelial cells. The final histopathological examination showed an endometriotic cyst with prominent stromal decidualization, omental tissues with deciduosis, and reactive mesothelial cells [Figure 4]. The patient tolerated the procedure well. She was discharged after 2 days. At 34 weeks 5 days AOG, the patient had strong regular contractions associated with vaginal bleeding. She eventually delivered to a live preterm baby girl through normal spontaneous delivery with APGAR score of 9 remaining 9, birthweight of 1795 grams, and Ballards score of 35 weeks. The baby was admitted at the Intensive Care Unit for 5 days and was subsequently sent home on the 8th day of life. Case 2 A 30-year old gravida 2 para 1 (1001) came in for her first prenatal consult at our institution. She was on her 15th week AOG and was complaining of intermittent abdominal pain. Three months before consult, the patient had missed menses with associated intermittent right lower quadrant abdominal pain, crampy, pain scale 7/10, spontaneously resolving. There were no other associated signs and symptoms such as vaginal bleeding or abnormal vaginal discharge. She had a previous transvaginal ultrasound done at another institution, which showed a single intrauterine pregnancy with good cardiac activity. The left ovary was normal, but the right ovary measures 4.9 cm × 4.2 cm × 4.1 cm and was described as unilocular, cystic, thick-walled, with medium level echoes at the lateral pole suggestive of endometriotic cyst versus dermoid cyst [Figure 5]. The patient was managed as a case of threatened miscarriage and was prescribed isoxsuprine tablet and dydrogesterone tablet. Persistence of symptoms prompted consult at our institution. A repeat transvaginal ultrasound done showed an intrauterine pregnancy at 15 weeks and 1 day by fetal biometry with good cardiac activity. The left ovary was normal in size and echotexture with the corpus luteum. The right ovary was seen occupying the cul-de-sac, seemingly adherent to the posterior uterine wall measured 6.1 cm × 4.9 cm × 3.6 cm and contained a unilocular cystic structure with uniform low-level echoes and lobulated solid papillary projections measuring 5.0 cm × 4.0 cm × 3.3 cm. There was a strong color flow (color score = 4) at its periphery and within the papillary projections. Wall thickness was measured at 0.27 cm [Figure 6]. A decidualized endometriotic cyst was considered versus an ovarian malignancy. After thorough counseling, the patient opted for a surgical intervention and underwent right oophorocystectomy. The patient was referred to a gynecologic oncologist preoperatively. Intraoperatively, the uterus was enlarged to 16 weeks AOG, with smooth serosal surface. The left ovary was grossly normal, plastered to the left posterior portion of the uterus. Both fallopian tubes were grossly normal. The right ovary was seen at the posterior cul-de-sac, densely adherent to the right posterior portion of the uterus and was enlarged to 6 cm × 6 cm [Figure 7]. The final histopathological examination showed an endometriotic cyst with decidual change. On gross inspection, the specimen consisted of a unilocular lesion measuring 3.4 cm × 2.5 cm × 1.8 cm in its collapsed state. The external surface was cream tan and the internal surface tan to brown with wall thickness of 0.2 cm. Several cream tan, irregular, soft tissue fragments were also seen with an aggregate measurement of 3 cm × 3 cm × 0.8 cm [Figure 8]. Microscopically, there was note of the presence of endometrial stroma and hemosiderin-laden macrophages indicative of chronic hemorrhage. Large polygonal cells having bland nuclei and moderate to abundant eosinophilic cytoplasm were present, which indicate marked decidual change of the stroma [Figure 9]. The patient was discharged improved 3 days postoperatively. She eventually delivered at 39 weeks 1 day AOG to a live term baby girl via normal spontaneous delivery to a live term baby girl, Apgar score 9, 9, birthweight of 3588 g, Ballards score 39 weeks.

Most adnexal masses in pregnancy are asymptomatic. Majority are only detected during the first ultrasound on prenatal checkup. Clinically, these masses are often missed during physical examination because of the enlarging uterus. We presented with two cases of endometrial cyst during pregnancy, both of which were detected during a routine ultrasound on prenatal checkup. The first case was asymptomatic, with the incidental finding of an ovarian mass during routine prenatal ultrasound. The second case was symptomatic complaining of abdominal pain and had a prior history of endometrial cyst versus dermoid cyst in a previous scan. Discovery of an adnexal mass during pregnancy poses several problems, particularly with the diagnosis and the therapeutic modalities. Determining the nature of the mass has an enormous clinical impact on its management. Expectant management or observation is reasonable if a tumor is suspected to be benign is suspected to be benign except for emergency situations wherein a benign tumor is complicated by torsion or rupture. However, when a malignancy is suspected, a surgical intervention might be warranted, which may indirectly affect the pregnancy outcome through preterm labor, massive hemorrhage, or removal of a corpus luteum cyst. Ultrasound is the first-line imaging modality to evaluate the nature of an adnexal mass. As previously mentioned, differentiating a benign from a malignant lesion is important since clinical management will depend on the classification. A three-step approach is used to classify these masses. The first step is using grayscale pattern recognition. Malignancy is suspected if irregularity, presence of septations, papillations, and solid structures are observed. Visualization of color flow on Doppler sonography further increases the probability of a malignant tumor. If classification cannot be achieved by pattern recognition, we proceed to application of the International Ovarian Tumor Analysis (IOTA) simple rules. The presence of benign (B) features in the absence of malignant (M) features would mean that it is a benign tumor. On the other hand, the presence of M features in the absence of B features makes it likely a malignant lesion. If B and M features are present, it is considered inconclusive. Benign features are as follows: (1) unilocular cyst, any size; (2) solid components either not present or <7 mm in diameter; (3) presence of acoustic shadowing; (4) smooth multilocular cyst <10 cm in diameter; and (5) no blood flow. On the other hand, malignancy is considered if these are present: (1) irregular solid tumor; (2) ascites; (3) at least four papillary structures; (4) irregular solid-multilocular tumor, largest diameter over 10 cm; and (5) very strong color flow. Its accuracy in diagnosing ovarian cancer has been proven by a meta-analysis study with a sensitivity of 93% and a specificity of 95%.[5] If IOTA simple rules turn out to be inconclusive, the next step will be using the IOTA Assessment of Different NEoplasias in the adneXa (ADNEX) model. The ADNEX model has clinical predictors and six ultrasonographic predictors. The clinical predictors comprise age in years, serum CA-125 (U/mL), and if the performing hospital is an oncology center. Ultrasound predictors include largest diameter of the mass (mm), maximal diameter of solid tissue (mm), number of papillary projections (0, 1, 2, 3, >3), presence of more than 10 locules, acoustic shadowing, and the presence of ascites. A risk of malignancy cutoff above 10% suggests malignancy. Case 1 presented with a multilocular-solid mass with solid structures, papillary projections, and moderate color flow (color score 3) on ultrasound. Calculated IOTA ADNEX risk of malignancy was 39.5%. Case 2 showed a unilocular-solid mass on ultrasound, with a papillary projection and strong color flow. Aided by a previous scan of endometriotic cyst, a decidualized mass was considered. The possibility of a malignancy, however, was not ruled out. Adnexal masses complicating pregnancy occur in 0.5%–1.2%. Most cases are benign and spontaneously regress during the second trimester, while some persist until after delivery. During pregnancy, decidualization of the endometriotic cyst may occur due to high levels of progesterone. Ectopic endometriotic implants grow and form a mass looking like a malignant tumor. Gestational deciduosis is usually seen in the ovary and cervix, but may have diverse presentations involving other organs such as the appendix,[6] kidneys,[7] and peritoneum.[8] In a prospective study done by Filippi et al., they estimated that 16% of endometriotic go through decidualization during pregnancy.[9] Sonologic diagnosis is easier in women with a known history of endometriomas cyst before pregnancy. An abrupt development of vascularized papillary projections in these women suggests decidualization rather than a malignancy. The diagnostic challenge lies in women with no known history of endometriotic cyst. Several studies have described the sonologic appearance of a decidualized endometrioma. Most are unilateral with intracystic excresences, less than 50% have solid components with color on power Doppler and no ascites.[9] Since the first case had no prior history of cyclic pelvic pain or a prior scan showing an endometriotic cyst, the possibility of a decidualized endometriotic cyst was not entertained sonologically. On the other hand, the second case had a prior scan, which showed a possible endometriotic cyst. Thus, decidualized endometrioma was suspected. In both cases, malignancy was still considered. Appearance of an ovarian mass in a previously normal ovary, along with the presence of a highly vascularized mass with solid areas on ultrasound, creates a diagnostic dilemma since these are classic features of malignancy. Differentiating a malignant mass from a decidualized endometriotic cyst is difficult as both are characterized by irregular internal surface with excrescences and strong vascularization of sonography. The use of magnetic resonance imaging (MRI) and tumor markers is limited in determining the nature of an adnexal mass. Though MRI was highly correlative with the final histopathology,[10] several studies have already proven that it does not provide additional information compared to an ultrasound. Tumor markers which are substances either produced by a tumor or as a result of a paraneoplastic conditions such as inflammation are often used to guide clinicians about nature of an adnexal mass. In a nonpregnant woman, CA 125 is a useful marker to classify adnexal masses. However, during pregnancy, they are of limited value since they are physiologically elevated. In some cases, they may be used for monitoring on follow-up. CA 125 done for the first case was elevated at 106.7 U/ml. No tumor markers were requested for the second case. By clinical assessment and by ultrasound evaluation, an ovarian malignancy was considered in both our cases. Patients were counseled, and with an informed consent, both opted for surgical intervention. Case 1 underwent peritoneal fluid sampling, oophorectomy, and infracolic omentectomy since a malignant process was highly considered. For case 2, since abdominal pain persisted in spite of medical treatment, surgical intervention (right oophorocystectomy) was done. Surgical resection of an adnexal mass is reserved for lesions that persist after the first trimester, for masses more than 10 cm, and if malignancy is suspected. Once the decision is made to remove the adnexal mass, several issues are considered, such as timing of intervention, choice of incision, and the extent of operation. Studies demonstrate safety of surgery during the second trimester.[11] This decreases the risk of first trimester complications associated with premature loss of corpus luteum and also prevents unnecessary surgery by allowing resolution of functional cysts.

Endometriotic cysts can co-exist with pregnancy. These 2 reported cases demonstrate that these endometriotic cysts can be mistaken for a malignancy necessitating surgical intervention during the pregnancy. The surgeries and the obstetric course had favorable outcomes for both cases. The decidualization of endometriotic cysts during pregnancy should be kept in mind as a process which can happen. Considering this, it can possibly change the approach on having immediate surgeries for these cysts during pregnancy. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their name and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Authorship contributions Kamille Angeli Rivera - Involved in conceptualization, data curation, writing original draft, visualization. Grace Laforteza - Involved in conceptualization, writing-review and editing, supervision. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Adnexal mass; deciduosis; endometriosis; pregnancy