Endometrioid borderline ovarian tumor arising from endometriotic cyst: short‐term change of sonographic appearance

Transvaginal ultrasonography has become a well-established imaging tool for the diagnosis and follow-up of pelvic endometriosis. The ultrasound diagnosis of an endometrioma is simple when the characteristics of the lesions are typical1. An endometrioma typically appears as a cyst with ground-glass echogenicity of the content, with one to four locules and without solid parts or papillary projections1. Conservative management is recommended in asymptomatic women with adnexal masses with benign ultrasound morphology, such as endometriomas, as the risk of malignancy and acute complications is low2. Furthermore, multiple surgeries can expose patients with endometriosis to surgical complications, iatrogenic adhesions and reduction of ovarian reserve. An asymptomatic 37-year-old woman, with negative serum CA 125 test result (27.2 U/mL), was referred for removal of a large endometrioma. Her history revealed a previous cervical adenocarcinoma (FIGO Stage IB) which was treated with laparotomic hysterectomy, bilateral salpingectomy and pelvic systematic lymphadenectomy 3 years earlier. During transvaginal ultrasound examination, a bilocular cyst measuring 103 × 56 × 70 mm was discovered on the left pelvic side, which had regular walls, ground-glass echogenicity of the content and absence of vascularization (color score, 1) (Figure 1a–c). The suspicion of an endometriotic cyst was confirmed and, because of its large size, surgery was planned. According to the International Ovarian Tumor Analysis (IOTA)-adnex model3, the probability of the lesion being a benign tumor was 97.7% and the risk of malignancy was 2.3%, with the risk of borderline tumor being 1.2%. The IOTA simple rules were inconclusive4, as no benign or malignant features were present. At the presurgical evaluation 4 months later, the cyst's characteristics were completely different as its size had increased and its morphology was altered (Videoclip S1), appearing as a multilocular-solid mass (12 locules), measuring 127 × 77 × 107 mm in size, with low-level echogenicity of the cyst fluid (Figure 1d). The solid component (43 × 27 × 38 mm) showed moderate vascularization (color score, 3) (Figure 1e). The contralateral ovary was normal in size and appearance, and no free fluid was seen in the pelvis or abdomen. Both scans were performed by experienced operators. Serum biomarkers showed CA 125 and CA 19-9 levels of 203 U/mL and 1763 U/mL, respectively. The patient was enroled into the IOTA6 study and, according to the IOTA-adnex model, the new risk of malignancy was 58%, the risk of a borderline tumor was 17.6% and the risk of Stage-I cancer was 21.8%. Specifically, the relative risk of borderline tumor and Stage-I ovarian cancer was similar (2.8 and 2.9, respectively), while the risk of Stage-II–IV cancer was 15.3% with a 3.4% risk of metastatic cancer. IOTA simple rules suggested a malignant lesion. Considering the previous findings, a malignancy arising from an endometriotic cyst was suspected. Laparotomic left oophorectomy, contralateral ovarian biopsy, and multiple peritoneal and omental biopsies were carried out. Histology showed an endometrioid borderline tumor arising from an endometriotic cyst, with a focal area highly suspicious for an endometrioid carcinoma (Figure 2). A second opinion was requested from a pathologist, who agreed with the diagnosis. Two peritoneal biopsies tested positive for borderline endometrioid tumor (FIGO Stage IIB). It is impossible to determine the real frequency at which endometriosis undergoes malignant changes5, but we know that endometrioid ovarian carcinoma is the most common tumor arising in ovarian endometriosis and 15–20% of endometrioid carcinomas are associated with endometriosis6. Our case showed significant changes on ultrasound examination within a short timeframe of 4 months. To the best of our knowledge, no other cases of benign-to-malignant ultrasound-morphology transformation of endometriotic cysts have beenpublished previously. A solid vascularized component characterizes endometriomas with malignant transformation (endometrioid borderline or carcinoma)7, as observed in our case. It is surprising that our mass did not manifest papillary projections, as Testa et al. reported that 13 of 15 malignant endometriomas contained papillary projections7. It is interesting to note that the cyst content of the lesion changed from ground-glass (typical of benign endometrioma) to low-level echogenicity. Testa et al. found low-level echogenicity of cyst content in 46.6% of endometriomas that became malignant. In large ovarian cysts, as observed in our case, assessment of wall regularity is limited and small papillary projections or any other small solid components may be missed. Therefore, close ultrasound surveillance is strongly suggested in large endometriomas for early detection of irregularities and papillary projections, in order to guide correct management. We thank Prof. Massimo Rugge (Department of Medicine (DIMED), Surgical Pathology Unit, University of Padua, Padua, Italy) for supervision and support for production of microscopic images. Videoclip S1 Grayscale and color Doppler ultrasound imaging of endometrioid borderline ovarian tumor arising from endometriotic cyst at second scan, showing multilocular-solid cyst with low-level echogenicity of content and irregular vascularized solid component. On color Doppler assessment, solid component showed moderate vascularization (color score, 3). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.