{"paper_id":"efd89c86-c6c6-4f43-b786-3ff072a37c74","body_text":"C A S E R E P O R T Open Access\nEndometrioid adenocarcinoma of the\nrectovaginal septum with invasion of the\nrectum: a case report and review of\nliterature\nHua Yang 1, Jiao-jiao Gu 1, Yue Qi 2, Wei Zhao 3 and Xin-lu Wang 1*\nAbstract\nBackground: Malignant transformation of endometriosis in the rectovaginal septum is rare and usually\nmisdiagnosed as a colorectal or gynecological tumor. We report a rare case of primary endometrioid\nadenocarcinoma of the rectovaginal septum with invasion of the rectum.\nCase presentation: A 57-year-old overweight woman presented with vaginal bleeding and self-reported left lower\nabdominal pain during the previous 2 weeks. Preoperative imaging showed a large pelvic mass with invasion of\nthe rectum, suggestive of a gynecologic malignancy. Multiple endoscopic biopsies and immunohistochemical\nanalyses of specimens was performed. The patient received joint gynecological-surgical laparotomy, and there were\nno intra- or postoperative complications. The histopathological diagnosis was rectovaginal endometrioid\nadenocarcinoma with rectum infiltration. The patient received adjuvant chemotherapy and achieved good\ntreatment response, with no early complications. At 12 months after surgery, there was no evidence of recurrence.\nConclusions: A high index of clinical suspicion is required for the diagnosis of endometrioid adenocarcinoma in\nthe rectovaginal septum. Surgery combined with additional chemotherapy or radiotherapy seems to be a standard\ntreatment, and hormonal therapy is optional. The efficacies of other therapies, including targeted medication and\nimmunotherapy, are unknown.\nKeywords: Endometrioid adenocarcinoma, Rectovaginal, Endometriosis, Malignant transformation, Diagnosis\nBackground\nEndometriosis is a chronic and benign gynecological dis-\nease most common in women of reproductive age, in\nwhich endometrial tissue occurs outside the uterine cav-\nity. The most common locations are the ovaries, fallo-\npian tubes, vagina, broad ligaments, cervix, pouch of\nDouglas, gastrointestinal tract, rectovaginal septum, and\nappendix [ 1, 2]. This disease affects approximately 6 to\n10% of women of reproductive age, and the most com-\nmon symptoms are chronic pelvic inflammation and\npain (especially dysmenorrhea) and subfertility [ 3–5].\nDeep-infiltrating endometriosis (DIE) is a sub-class of\nendometriosis which is defined by endometrial infiltra-\ntion of the peritoneum by more than 5 mm [ 6], and\nendometriosis of the rectovaginal septum is the most se-\nvere form [ 7]. Malignant transformation of endometri-\nosis is quite rare; it occurs in only 0.7 to 1% of patients\nwith endometriosis, and 78.7% of these cases have ovar-\nian malignancies [ 8, 9]. Primary adenocarcinoma of the\nrectovaginal septum is extremely rare and most cases\nare associated with benign endometriosis [ 10, 11]. In this\narticle, we report a patient with a primary adenocarcin-\noma arising from endometriosis in the rectovaginal\nseptum with involvement of the rectum.\n© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0\nInternational License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and\nreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to\nthe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver\n(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.\n* Correspondence: wangxl1@sj-hospital.org\n1Department of Ultrasound, Shengjing Hospital of China Medical University,\nShenyang, Liaoning Province, Republic of China\nFull list of author information is available at the end of the article\nYang et al. World Journal of Surgical Oncology          (2019) 17:206 \nhttps://doi.org/10.1186/s12957-019-1743-0\n\nCase presentation\nA 57-year-old post-menopausal woman (gravida 1, para\n1) was admitted to the Gynecology Department of\nShengjing Hospital (an affiliate of China Medical Univer-\nsity) presenting with vaginal bleeding and left lower ab-\ndominal pain for the previous 2 weeks. She had a\ncaesarean section and myomectomy more than 20 years\nago and denied any previous hormonal therapy. She was\n155 cm in height and 65 kg in weight (body mass index\n(BMI): 27.1 kg/m 2). Her mother had a history of pancre-\natic carcinoma and her father had a history of hepatic\ncarcinoma. She reported no history of weight loss or\nchange in appetite.\nThe physical and vaginal examination indicated a pel-\nvic mass on the left side with poor mobility. The\ngynecological examination indicated that the vagina, cer-\nvix, and uterus appeared normal. The laboratory tests\nshowed the serum level of CA125 was 207.5 U/mL (nor-\nmal < 35.0), CA199 was 59.9 U/mL (normal < 37), and\nHE4 was 206.9 U/mL (normal < 140.0), although the\nCEA and AFP levels were normal.\nA transvaginal ultrasound (TVS) showed an irregular\ncomplex mass (7.0 × 5.3 × 5.6 cm) in the recto-uterine\npouch that had an unremarkable boundary, but had\nabundant vascularities on the septa and solid portion of\nthe tumor (Fig. 1a). There was also invasion of the mass\ninto the anterior wall of the rectum (Fig. 1b). The right\novary was normal but the left ovary was not visible. A\npelvic ultrasound also showed multiple uterine leiomyo-\nmas. The endometrium was thickened and irregular, but\nthere was no evidence of ascites, peritoneal implants, or\nother masses.\nWe suspected ovarian carcinoma with invasion of the rec-\ntum, and thus performed a whole body FDG-positron emis-\nsion tomography (PET) (Fig.2). The F18-fluorodeoxyglucose\nPET/computed tomography (F18-FDG PET/CT) showed an\nirregular solid-cystic mass (5.0×4 . 3c m )i nt h er e c t o v a g i n a l\nfossa that had pathologic FDG-uptake and seemed to infil-\ntrate the rectum.\nThus, we also suspected a pelvic malignant tumor in-\nfiltrating the rectum. A colonoscopy (Fig. 3) indicated an\nulcerated lesion 10 cm from the anal margin that occu-\npied about 1/3 of the lumen, in which the covering mu-\ncosa were pale and the surrounding mucosa were\nclustered. This exam also indicated a 0.5-cm polyp in\nthe sigmoid colon. Multiple endoscopic biopsies were\ntaken during this procedure. An endoscopic ultrasono-\ngraphic examination indicated a protruding lesion (0.4 ×\n0.4 cm) in the fundus of the stomach (adjacent to the\ncardia) and another lesion with fixed echoes in the an-\nterior wall of duodenum (0.4 × 0.4 cm), which was be-\ntween the third and fourth layers of the duodenal wall.\nWe did not treat these due to their small sizes.\nThe pathological report of the biopsy specimen in-\ndicated evidence of a metastatic adenocarcinoma from\na gynecological malignancy with rectum involvement.\nThus, a joint gynecological-surgical laparotomy was\nperformed. Radical hysterectomy, bilateral adnexect-\nomy, pelvic peritonectomy, pelvic lymphadenectomy,\nomentectomy, partial rectal resection with a low pel-\nvic colorectal anastomosis protected by ileostomy, and\nappendectomy were performed. During this cytore-\nductive procedure, a 5.0-cm solid mass was identified\nin the recto-uterine pouch that closely adhered to the\nrectum and another 3.5-cm cystic mass on the upper\nrectovaginal septum. Because the mass did not invade\nthe vagina, and considering the patient ’s quality of\nlife, an upper vaginal resection with anastomosis was\nperformed, so that the middle and lower segment of\nthe vagina were retained. There were apparent adhe-\nsions in the pelvic cavity, especially between the tu-\nmors and the rectosigmoid. The bilateral adnexa were\natrophic, without any obvious macroscopic tumor.\nThere was no evidence of residual macroscopic le-\nsions or intraoperative complications after surgery.\nAnalysis of the resected sp ecimens indicated the rec-\ntal specimen had a thickened wall with coarse mucosa\nand serosa (Fig. 4). When opening the cystic mass\nFig. 1 Transvaginal ultrasound (TVA), showing an irregular complex mass in the rectovaginal fossa. a Abundant vascularities on the septa and\nsolid portion of the tumor (arrows). b Invasion of the mass into the anterior wall of the rectum (arrows)\nYang et al. World Journal of Surgical Oncology          (2019) 17:206 Page 2 of 8\n\nadhering to the rectum, the internal wall was gray-\nyellow in color with cauliflow er-like lesions. For histo-\nlogical analysis, specimens were fixed in 10% buffered\nformalin, processed, and embedded in paraffin. Micro-\nscopic analysis indicated the tumor cells were acinar,\nFig. 2 Positron emission tomography/computed tomography (PET/CT), showing a mass with fluorodeoxyglucose (FDG) uptake in the\nrectovaginal fossa. a CT image showing a cystic-solitary mass. b PET/CT image showing a mass with FDG uptake (maximum standardized uptake:\n11.32). c, d FDG images\nFig. 3 Colonoscopy indicating an ulcerated lesion of the\nrectum (arrow)\n Fig. 4 Section of the rectal specimen indicating a thickened wall\nYang et al. World Journal of Surgical Oncology          (2019) 17:206 Page 3 of 8\n\nwith papillary structures that were moderately differ-\nentiated, and heteromorphic cells were arranged in a\nsieve pattern (Fig. 5). Endometriosis was also evident\nin the left adnexa (Fig. 6).\nImmunohistochemical studies performed using the\navidin-biotin peroxidase complex technique indicated\npositive staining for cytokeratin 7 (CK7), estrogen recep-\ntor (ER), paired box gene 8 (PAX-8), and Wilms tumor\nprotein (WT-1), weakly positive staining for progester-\none receptor (PR), and no staining for CK20, caudal-\nrelated homeobox 2 (CDX-2), vimentin, P53 proteins,\nand villin (Fig. 7). In addition, 10% of the cells were posi-\ntive for Ki-67 (data not shown). The final histopatho-\nlogical diagnosis was rectovaginal endometrioid\nadenocarcinoma with rectum infiltration. Thus, the pa-\ntient received 6-month adjuvant chemotherapy and\nachieved good treatment response. The patient has been\nfree of disease for 12 months since the surgery. A\nfollow-up at that time, which included enhanced CT and\nTVS, showed no evidence of recurrence.\nDiscussion and conclusions\nEndometriosis is a common gynecological disease\namong premenopausal women that is characterized by\nuncontrolled endometrial cell proliferation, with local\nand distant spread of these cells [ 12]. Although endo-\nmetriosis is not considered a premalignant disease, it\nmay nonetheless have malignant potential and aggres-\nsive pathology, characterized by high local invasive-\nness and recurrence [ 13]. In 1925, Sampson [ 14]f i r s t\ndescribed malignant transformation in a patient with\nendometriosis. This condition may occur in 0.7 to 1%\nof women with endometriosis [ 15]; it is most com-\nmon in the ovary, but about 20% of cases have malig-\nnancies at extragonadal sites [ 16]. Sampson [ 14]a n d\nScott [ 17] proposed four basic criteria for diagnosis of\nendometriosis-associated cancer: (i) malignant and be-\nnign endometrial cells coexist within the same tissue;\n(ii) the malignancy originates from the same tissue,\nwithout metastasis or infiltration from other sites; (iii)\nthere are no other primary sites; and (iv) the adjacent\nendometriosis focus is contiguous with the endome-\ntrioid carcinoma tissue. Our patient fulfilled all four\ncriteria.\nThe rectovaginal septum is a relatively common site\nfor extragonadal endometriosis, followed by the ovary.\nAlthough endometriosis-associated rectovaginal adeno-\ncarcinoma is extremely rare, it accounts for 70% of\nprimary rectovaginal malignancies [ 18, 19]. A recent\ncomprehensive review [ 19] found reports of fewer than\n20 primary carcinomas of the rectovaginal septum aris-\ning from endometriosis. We identified 8 full-text articles\npublished in English between 1950 and 2018 that de-\nscribed 9 patients with primary endometriosis-associated\ncarcinoma (Table 1). As expected, adenocarcinoma is\nthe most common histologic type of extragonadal\nendometriosis-associated neoplasm (6 cases including\nthe present patient). The less common histologic forms\nwere clear cell carcinoma, stroma sarcoma, adenoa-\ncanthoma, and carcinosarcoma [ 20].\nFig. 5 Histopathological findings (hematoxylin-eosin (H&E) staining, 100×). a Adenocarcinoma invasion of the rectum. b Solid part of the tumor,\nindicating heteromorphic cells arranged in a sieve pattern\nFig. 6 Histopathological findings (H&E staining, 100×), showing\nendometriosis in the left adnexa\nYang et al. World Journal of Surgical Oncology          (2019) 17:206 Page 4 of 8\n\nThe etiology of rectovaginal endometriosis remains un-\ncertain. One possible mechanism is the adhesion and\ngrowth of endometrial tissues that were deposited into the\nperitoneal cavity via retrograde menstruation. It is also\npossible that the origin is from metaplasia of the Müller-\nian remnants in the rectovaginal septum [ 21]. Endometri-\nosis is an estrogen-dependent disease, and some evidence\nindicated that endogenous or exogenous hyperestrogen-\nism may contribute to the malignant transformation [ 9].\nYoung et al. [ 22] reported a patient with rectovaginal\nendometriosis-associated adenocarcinoma who was taking\nhigh-dose unopposed estrogens (1.25 mg conjugated es-\ntrogens per day) for 14 years after a subtotal hysterectomy.\nOn the other hand, obesity also increases the risk for de-\nveloping cancer from endometriosis. Three of the 8\nwomen with rectovaginal tumors arising from endometri-\nosis were obese (Table 1)[ 23, 24]. Our patient did not use\nunopposed estrogens, but her BMI was above normal. It is\nalso interesting to note that 6 of the 10 (60%) cases we\nreviewed (including our patient) had previous lower ab-\ndominal/pelvic surgery, including hysterectomy. Thus,\npelvic surgery itself could increase the risk for dissemin-\nation of endometriotic lesions and malignant\ntransformation of rectovaginal endometriosis. Okimura\net al. [8] also mentioned this possibility.\nThe average patient age was 43.2 years. Our patient\nwas 57 years old, older than any of the other 9 pa-\ntients. Women with rectovaginal endometriosis –asso-\nciated adenocarcinoma often complain of dyschezia,\ndeep dyspareunia, abdominal or pelvic pain, and vagi-\nnal or rectal bleeding. Our patient ’s chief complaints\nwere vaginal bleeding and left lower abdominal pain.\nIn fact, due to the deep location of these tumors and\nthe atypical clinical symptoms, diagnosis is often diffi-\ncult, so these tumors often remain latent for a long\ntime before diagnosis. In the present case, the tumor\nwas already more than 5 cm in diameter, and it had\ninfiltrated the entire wall of the rectum upon diagno-\nsis. In all cases, diagnosis requires surgery and patho-\nlogic examination.\nFor the very few cases of previously reported rectovaginal\nseptum tumors arising from endometriosis, modern imaging\ntechniques were usually used for initial evaluation of local\nand regional extension of the tumor, but were insufficient\nfor diagnosis because the resul ts are also consistent with\nuterine or ovarian tumors, just as in our patient.\nFig. 7 Immunohistochemical (IHC) staining of tumor cells for 5 markers (100×). a PAX-8 (positive). b ER (positive). c CK7 (positive). d CK20\n(negative). e CDX-2 (negative)\nYang et al. World Journal of Surgical Oncology          (2019) 17:206 Page 5 of 8\n\nTable 1 Characteristics of our patient and previously reported patients with rectovaginal septum tumors related to endometriosis\nAuthor/year Patient\nage\n(years)\nSigns/symptoms Medical history Body type Laboratory\ntests\nRadiology/ultrasonic\nfindings\nHistology Treatment Follow-up\nDockerty\net al. [ 1],\n1954\n54 Serosanguineous\nvaginal discharge\nThyroidectomy ND ND ND Adenocarcinoma TH+BSO+LN/RT DOD 2\nyears\nDockerty\net al. [ 1],\n1954\n45 A small reddish\narea on the\nposterior lip of\nthe cervix\nND Obese Normal ND Adenocarcinoma TH+BSO+LN/RT NR 10\nyears\nLash and\nRubenstone\n[2], 1959\n32 Severe low back\npain, cyclic\nvaginal bleeding\nSTH Obese Normal Upper and lower\ngastrointestinal roentgen\nstudies were normal\nAdenocarcinoma Cervicectomy, RR ND\nYoung and\nGamble [ 3],\n1969\n47 Intermittent\nvaginal bleeding,\npelvic pain, and a\ncul-de-sac mass\nSTH ND ND ND Adenoacanthoma Pelvic exenteration+RT Unknown\nGoldberg\net al. [ 4],\n1978\n48 A hemorrhagic\nnodule on the\nposterior vaginal\nwall\nSpontaneously aborted\nthrough a laceration\nND ND ND Clear cell\nadenocarcinoma\nTH+LN+RR+resection of the upper half of the vagina Metastatic\nnodes 9\nmonths\nlater\nAddison\net al. [ 5],\n1979\n37 Vagina1 and\nrectal bleeding\nTH+celiotomy+nephrectomy Obese ND ND Adenoacanthoma RT/CT DOD 1\nyear\nYazbeck\net al. [ 6],\n2005\n25 Lower abdominal\npain and\ndyspareunia;\npainful\nretrocervical\nnodule\nTotal thyroidectomy +\nappendectomy\nND CA125: 700\nU/mL\nUS showed a\nheterogeneous pelvic\nmass; MRI confirmed the\ncentral pelvic mass.\nPapillary\nadenocarcinoma\nRT/TH+RR NR 2 years\nUlrich et al.\n[7], 2005\n51 Irregular vaginal\nbleeding\nVaginal hysterectomy ND ND Pelvic MRI confirmed a\ntumor of the\nrectosigmoid colon\nGlandular and\npapillary tumor\nRR+BSO+vagina and parakolpium resection+LN+RT RE 2 years\nlater\nMabrouk\net al. [ 8],\n2011\n36 Abdominal\ndiscomfort\nUnknown ND Ca125 and\nCa19.9\nwere\nelevated\nCT scan showed a retro-\nuterine mass; US scan re-\nvealed both slightly en-\nlarged ovaries and a\nretrocervical mass\nClear cell and\nendometrioid\nadenocarcinoma\nTH+LN+omentectomy+appendicectomy+CT\n(cisplatinum)+RR□\nNR 2\nmonths\nPresent\ncase, 2019\n57 Vaginal bleeding\nand left lower\nabdominal pain\nCaesarean section and\nmyomectomy\nOverweight Ca125,\nCa19.9,\nand HE4\nwere\nelevated\nUS scan showed an\nirregular complex mass in\nthe rectovaginal fossa,\nPET/CT showed a mass\nwith FDG uptake in the\nrectovaginal fossa.\nAdenocarcinoma TH+LN+omentectomy+peritonectomy+appendicectomy+\npartial rectal resection+CT\nNR 6\nmonths\nRT, radiation therapy; TH, total hysterectomy; STH, subtotal hysterectomy; BSO, bilateral salpingo-oophorectomy; LN, lymph node dissection; CT, chemotherapy; RR, rectal resection; RE, recurrence; NR,n o\nrecurrence; DOD, dead of disease; ND, not described; US, ultrasound; MRI, magnetic resonance imaging; PET/CT, positron emission tomography/computed tomography; FDG, fluorodeoxyglucose\nYang et al. World Journal of Surgical Oncology          (2019) 17:206 Page 6 of 8\n\nTransvaginal ultrasound (TVS) is a first-line technique used\nto examine a pelvic mass and DIE. In particular, TVS can\nevaluate the exact location and extent of infiltration, which\nis important for determining the type and difficulty of sur-\ngery [25]. For instance, TVS of our patient showed a large\nmass in the recto-uterine pouch with rectal wall infiltration.\nMoreover, magnetic resonance imaging (MRI) can also help\nto evaluate deep lesions in the rectovaginal region. A meta-\nanalysis by Guerriero et al. [ 4] demonstrated similar diag-\nnostic performance of TVS and MRI in the detection of\nDIE, confirming the role of TVS as a cost-effective first-line\ntechnique. Nevertheless, preoperative imaging techniques\nare only useful for estimation of the location and extent of\ninfiltration, and cannot be used to determine malignant\ntransformation of endometriosis. When rectum infiltration\nis suspected, diagnostic rectoscopy or colonoscopy should\nbe performed, and endoscopic biopsies may also be needed\nfor pathological examination. In our patient, pathological\nanalysis of the colonoscopy biopsy specimen indicated a\nmetastatic adenocarcinoma from a gynecological\nmalignancy.\nAfter biopsy or resection of the tumor, immunohisto-\nchemical staining (IHC) may be essential to confirm the\ndiagnosis. IHC staining using antibodies against ER, PR,\nCK7, PAX-8, CK20, and CDX2 is extremely useful for the\ndifferential diagnosis of endometrioid adenocarcinoma and\nprimary intestinal adenocarcinoma. In particular, IHC\nstaining for CK7 and CK20 can differentiate endometrioid\nand primary rectal carcinoma [ 26]. Many colorectal\ncarcinomas are CK20-positive and CK7-negative, but\ngynecological tumors (including endometrioid carcinomas)\nare often CK20-negative and CK7-positive. PAX-8 is a spe-\ncific marker of Müllerian origin and is also expressed in\ngynecological tumors. Furthermore, the ER is expressed in\nmost uterine endometrioid adenocarcinomas. On the other\nhand, CDX2 (a homeobox transcription factor) is expressed\nduring normal intestinal development [ 27]. Thus, CDX2\nexpression may be positive in colorectal cancers and has\nhigh sensitivity for the differential diagnosis of colorectal\nadenocarcinoma [28]. Our patient had positive IHC stain-\ning for CK7, ER, and PAX-8, and negative staining for\nCK20 and CDX-2, compatible with our diagnosis of endo-\nmetrioid adenocarcinoma.\nThere is currently no consen sus on the standard thera-\npeutic approach to be used for treating extraovarian endo-\nmetriosis–associated malignancie s, and studies in the\nliterature report the use of highly individualized treatments.\nHowever, primary surgical excision or radical resection of\nthe tumor should be performed if feasible. Including our\npatient, 9 of 10 cases received surgery (Table 1). Among\nthe previous 9 cases, 7 received total hysterectomy and/or\nsalpingo-oophorectomy and 2 received local resection.\nMoreover, 6 patients received rectal resections and 6 pa-\ntients received lymph node dissections. Some clinicians\nhave offered adjuvant therapy, including chemotherapy and\nradiotherapy. Therefore, chemotherapy may be the first-\nline adjuvant treatment for aggressive malignant transform-\nation of extragonadal endometriosis [ 29]. Similar to treat-\nments for endometrial cancer, the chemotherapeutic\nregimens typically consist of platinum-taxane combinations.\nThe therapeutic value of chemotherapy for extragonadal\nendometriosis–associated cancer is unclear. Radiation ther-\napy may be performed after surgery or for treatment of\nlocal recurrence after the pri mary surgery and chemother-\napy. Because of the rarity of this disease, neoadjuvant ther-\napy should be considered, as should hormone-therapy for\ngestagen receptor-positive endometriosis-associated cancers\n[30]. Primary endometrioid adenocarcinoma of the rectova-\nginal septum has much better prognosis than endometrioid\ntumors at other sites [11].\nIn conclusion, endometrioid adenocarcinoma of the rec-\ntovaginal septum is a rare malignant tumor that requires a\nhigh index of clinical suspicion for successful diagnosis.\nClinicians must differentiate this tumor from colorectal\ncancers so that the most appropriate treatment is adminis-\ntered. Because of the rarity of this tumor, we cannot draw\nany conclusions regarding preoperative diagnosis. We sug-\ngest clinical suspicion in patients previously diagnosed\nwith endometriosis who present with abdominal pain and\nvaginal or rectal bleeding, especially in women taking un-\nopposed estrogens. Several imaging techniques can help\nevaluate local and regional extension of the tumor. IHC\nstaining is essential for the final diagnosis. Surgery com-\nbined with chemotherapy or radiotherapy seems to be the\nstandard treatment for rectovaginal malignancies arising\nfrom endometriosis, but hormonal therapy could be con-\nsidered depending on the individual patient. However, be-\ncause of the rarity of this condition, identification and\ncharacterization of additional patients is essential. The ap-\nplication of targeted medication and immunotherapy may\nhelp to improve prognosis.\nAbbreviations\nAFP: Alpha-fetoprotein; BMI: Body mass index; CA125: Cancer antigen 125;\nCA19-9: Cancer antigen 19-9; CEA: Carcinoembryonic protein antigen; CDX-\n2: Caudal-related homeobox 2; CK7: Cytokeratin 7; CK20: Cytokeratin 20;\nDIE: Deep-infiltrating endometriosis; F18-FDG PET/CT: F18-\nfluorodeoxyglucose PET/computed tomography; ER: Estrogen receptor;\nHE4: Human epididymis secretory protein 4; IHC: Immunohistochemical;\nMRI: Magnetic resonance imaging; PAX-8: Paired box gene 8;\nPR: Progesterone receptor; TVS: Transvaginal ultrasound; WTP-1: Wilms tumor\nprotein-1\nAcknowledgements\nNot applicable.\nAuthors’ contributions\nHY designed and revised the manuscript. YQ performed the operation. WZ\nperformed the pathological imaging. XLW edited the manuscript. JJG made\ncontributions to the acquisition of data and imaging. All authors read and\napproved the final manuscript.\nYang et al. World Journal of Surgical Oncology          (2019) 17:206 Page 7 of 8\n\nFunding\nThis study was supported by research program from the National Natural\nScience Foundation of China (NSFC) (Grant No. 81501496).\nAvailability of data and materials\nThe datasets generated and analyzed during the present study are available\nfrom the corresponding author on reasonable request.\nEthics approval and consent to participate\nThis study was approved by the ethics committee of Shengjing Hospital of\nChina Medical University. All procedures performed in studies involving\nhuman participants were in accordance with the ethical standards of the\ninstitutional and/or national research committee and with the 1964 Helsinki\ndeclaration and its later amendments or comparable ethical standards.\nWritten informed consent was obtained from the patient.\nConsent for publication\nAll data published here are under the consent for publication. Written\ninformed consent was obtained from all individual participants included in\nthe study.\nCompeting interests\nThe authors declare that they have no competing interests.\nAuthor details\n1Department of Ultrasound, Shengjing Hospital of China Medical University,\nShenyang, Liaoning Province, Republic of China. 2Department of Obstetrics\nand Gynecology, Shengjing Hospital of China Medical University, Shenyang,\nLiaoning Province, Republic of China. 3Department of Pathology, Shengjing\nHospital of China Medical University, Shenyang, Liaoning Province, Republic\nof China.\nReceived: 13 August 2019 Accepted: 6 November 2019\nReferences\n1. Verma R, Osborn S, Horgan K. Endometrioid adenocarcinoma of caecum\ncausing intussusception. Case Rep Surg. 2013;2013:714126.\n2. Zhao LJ, Wang YH, Zhang JD. A case report: rectal endometriosis mimicking\nrectal cancer. Int J Surg Case Rep. 2018;53:137 –9.\n3. Rafique S, Decherney AH. Medical management of endometriosis. 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