Clear Cell Carcinoma of the Abdominal Wall: An Aggressive Endometriosis-Associated Malignant Disease

Endometriosis rarely affects the abdominal wall and typically occurs following surgery, like uterine procedures or, more commonly, cesarean sections. There have been a few instances of endometriosis evolving into malignant clear cell carcinoma. Our goal was to examine all relevant cases documented in the literature and introduce a new case. In this article, we analyze reported occurrences of clear cell carcinoma in the abdominal wall and share the case of a 45-year-old woman with a mass on her front abdominal wall. An initial biopsy revealed clear cell carcinoma of the female genital tract. In our facility, she underwent extensive surgery involving the removal of the mass along with sections of the abdominal wall, uterus, fallopian tubes, ovaries, omentum, suspicious lymph nodes, and reconstruction of the abdominal wall using a double-sided mesh. She had a smooth recovery after the operation, but a month later, prior to commencing chemotherapy, she developed metastases in the liver and lungs. She was treated with systemic therapy and, after six months, displayed a positive response with some reduction in the disease. As of 15 months post- surgery, she is doing well under ongoing treatment. Clear cell carcinoma of the abdominal wall is an uncommon and aggressive cancer with a grim outlook. Physicians should be wary of the potential for malignancy in women with an abdominal wall mass and a history of gynecological surgeries, especially cesarean sections. Categories: Obstetrics/Gynecology, Pathology, Oncology

abdominal wall endometriosis, cesarean section, clear cell carcinoma, malignant transformation, surgical scar endometriosis

Endometriosis is a chronic, inflammatory, estrogen-dependent gynecological disorder characterized by the presence of endometrial-like tissue outside the uterine cavity, most commonly affecting the ovaries, pelvic peritoneum, and deep pelvic structures [1,2] . It affects approximately 10-15% of women of reproductive age, and it is frequently associated with chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility [3] . Rarely, endometriotic nodules are found outside the pelvis, including the abdominal wall [4] . Abdominal wall scar endometriosis was first described in 1903, according to previous reports [5] . The reported incidence rate varies from 0.03 to 1.08% [6] . Despite its benign histological appearance [7] , endometriosis demonstrates several features, typically associated with neoplastic processes, including local invasion, resistance to apoptosis, angiogenesis, and the capacity for recurrence [8] . In recent years, increasing attention has been given to the potential relationship between endometriosis and malignancy. Although the absolute risk of malignant transformation remains low, estimated at approximately 1% of women with endometriosis, the possibility of neoplastic progression raises important clinical and research considerations [5,9] . Over 80% of endometriosis-related malignancies occur in the ovaries [10] , whereas 20% of them are located in extra-gonadal sites [11] , including intestine, rectovaginal septum, abdominal wall, pleura, and others [1,12] . The exact mechanisms behind the malignant transformation of endometriosis remain unclear [13] . Consequently, continued investigation into the mechanisms linking endometriosis and malignancy is essential for advancing both the prevention and management of endometriosis-associated cancers. This article was previously presented as an e-poster at the ESGO (European Society of Gynaecological Oncology) 2026 Congress on February 27, 2026. Case Presentation 1 2 2 3, 1 4 5 1 1 Open Access Case Report How to cite this article Bourou M, Myoteri D, Vlahos I, et al. (July 04, 2026) Clear Cell Carcinoma of the Abdominal Wall: An Aggressive Endometriosis-Associated Malignant Disease. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 A 45-year-old patient, mother of two young children, was admitted to our hospital with a histologically proven clear cell carcinoma (CCC) of the anterior abdominal wall. Her past medical history included type 1 diabetes mellitus (T1DM), two cesarean sections, and resection of an abdominal wall endometriotic lesion 5 years ago. During the last year, she noticed a palpable mass in the midline of the abdomen, which gradually increased in size. She underwent surgical excision of this mass, and the histological report showed clear cell carcinoma arising from the female genital tract. The tumor was completely excised, albeit with only 1 mm clear resection margins. Upper and lower abdominal magnetic resonance imaging (MRI) revealed some nodular lesions with limited diffusion to the anterior lower abdominal wall and inside the posterior rectus abdominis sheath. A thin- walled 1.9 cm cystic formation in the left ovary and a 1.5 cm right external iliac lymph node were also observed. PET-CT revealed areas of significantly increased radiopharmaceutical uptake in contact with the posterior margins of the right and left rectus abdominis muscles. Also, a slightly enlarged hypermetabolic right external iliac lymph node was identified, while chest CT did not show pathologically enlarged lymph nodes or other suspicious findings. Serum tumor markers were normal. Specifically, cancer antigen (CA)-125 was 17 U/ml, CA 19.9 was 6.48 U/ml, carcinoembryonic antigen (CEA) was 1.26 U/ml, human epididymis protein 4 (HE4) was 28.2 pmol/L, and the premenopausal Risk of Ovarian Malignancy Algorithm (ROMA) score was normal at 2.2% (Table 1 ). Laboratory Parameter Patient Value

Range Units CA-125 17 0-35 U/ml CA 19.9 6.48 0-37 U/ml CEA 1.26 <5 ng/ml HE4 28.2 <70 pmol/L Premenopausal ROMA score 2.2 <7.4 % TABLE 1: Preoperative tumor marker profile of the patient Abbreviations: CA-125, cancer antigen 125; CA 19-9, carbohydrate antigen 19-9; CEA, carcinoembryonic antigen; HE4, human epididymis protein 4; ROMA, Risk of Ovarian Malignancy Algorithm The Tumor Board Meeting advised surgery and adjuvant chemotherapy. The patient underwent extensive debulking surgery, including anterior abdominal wall resection, total hysterectomy with bilateral salpingo- oophorectomy (BSO), infracolic omentectomy, excision of enlarged pelvic and infra-aortic lymph nodes, and abdominal wall repair with double-sided pre-peritoneal mesh, with no macroscopic residual disease (Figure 1 , Figure 2 ). The estimated blood loss was 800 ml, and there were no intra- or post-operative complications. She was discharged on the 4th postoperative day in good condition and made an uneventful recovery. 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 2 of 10 FIGURE 1: Anterior abdominal wall resection (A) Anterior surface; (B) posterior surface FIGURE 2: Total hysterectomy with bilateral salpingo-oophorectomy and infracolic omentectomy (C) and reconstruction of the abdominal wall with double-sided mesh (D) On final histology, the uterus, fallopian tubes, ovaries, omentum, 25 pelvic lymph nodes and 10 para-aortic lymph nodes were unremarkable, with no evidence of malignancy. In the en bloc-excised dermal- subcutaneous-fascial and muscular section of the whole abdominal wall, multiple nodules of CCC were identified, which appeared to have arisen in the setting of endometriosis (Figure 3 ). The margins of the specimen were free of disease. Immunophenotype of cancer cells: Napsin+, focal Ker7+, p53 wild type, ER-, PR-, CD10-, WT1-, PAX8+, Vimentin+, Ki-67 proliferation index: 40%. Genetic testing for BRCA1 and BRCA2 mutations and homologous recombination deficiency (HRD) was negative.. 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 3 of 10 FIGURE 3: Histology image: microscopically, the oval-shaped foci were a focus of CCC with typical hobnail morphology. Hematoxylin and eosin (H&E) staining; original magnification x40 CCC: clear cell carcinoma Unfortunately, four weeks after surgery, imaging revealed new metastatic hepatic and pulmonary lesions. The patient completed six cycles of intravenous carboplatin, paclitaxel, and bevacizumab. Six months after completion of systemic treatment, imaging showed a significant response, and the patient started a maintenance therapy with continuation of bevacizumab. After another 3 months, imaging showed significant improvement, with near-complete resolution of the pulmonary metastases and a significant reduction of the liver metastases. Systemic treatment with bevacizumab was continued and, after 15 months following surgery, the patient remains well and in stable condition.

We know that endometriosis itself has a complicated pathophysiology that involves several elements. The most widely accepted theory for the development of endometriosis is retrograde menstruation, where endometrial tissue flows through the fallopian tubes and implants in the peritoneum [8] . Other theories, including endometrial stem cell implantation, Müllerian remnant abnormalities, and coelomic metaplasia, have also been proposed [7] . In addition, immunological dysregulation, genetic and epigenetic factors, and environmental variables may all contribute to endometriosis genesis and progression [13,14] . According to recent research, endometriosis and cancers linked to endometriosis share several genetic changes, including loss of heterozygosity, PTEN , ARID1A , p53 , and KRAS mutations [15] . There is new evidence linking ovarian carcinogens to the dysregulation of microRNAs [9] . Other pathways link immune response disruptions and oxidative stress to a two-step process for the pathogenesis of endometriosis [15] . Several risk factors, related to the malignant transformation of endometriosis, have been identified. These include ovarian endometriomas, endometriosis linked to infertility, women with long-standing endometriosis, hyperestrogenism, and endometriosis identified at a young age [16,17] . In addition, genetic abnormalities involving the loss of heterozygosity on chromosomes 4 and 5q [16] , and carcinogens, such as polychlorinated biphenyls, may be involved [18] . Due to the lack of high-quality data, there is uncertainty about whether postmenopausal women with endometriosis could receive hormonal treatment [1,14] . In 1925, Sampson outlined the first diagnostic criteria for endometriosis-associated ovarian cancer (EAOC), including: 1) demonstration of benign and neoplastic endometrial tissues in the tumor, 2) the histology being compatible with endometrial origin, and 3) with no other discoverable primary tumor sites [8,9,19] . In 1953, Dr. Scott proposed a fourth criterion for diagnosing malignant endometriosis, which is the histological proof of a transition or dysplastic phase between benign endometriosis and the malignant tumor [20] . This criterion highlights the possibility of malignant transformation within the endometriosis 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 4 of 10 itself, rather than simply the presence of a malignant tumor in the same location [8,15,19] . Author Year Age Surgical History CE Surgical Treatment Nodal Evaluation Adjuvant Treatment Clinical Course Outcome 1 Schnieber [21] 1986 40 CS Yes Wide resection No RT SD DOD 2 Hitti [22] 1990 46 CS Yes Local Excision No RT NM NED 3 Miller [23] 1998 38 CS Yes Local Excision No RT NM NED 4 Park [24] 1999 54 CS Yes Local Excision No RT NM NED 5 Ishida [25] 2003 56 CS No Local Excision No RT LR DOD 6 Sergent [26] 2006 45 CS No Local Excision No RT, CT LR DOD 7 Alberto [27] 2006 38 CS No Local Excision No RT, CT RPD DOD 8 Razzouk [28] 2007 46 CS Yes Local Excision No CT RPD DOD 9 Harry [29] 2007 55 TS Yes Wide resection NR RT NM NR 10 Rust [30] 2008 38 CS Yes Local Excision No CT NM NR 11 Bats [16] 2008 42 TAH Yes Wide resection NR None NM NR 12 Achach [31] 2008 49 Myomectomy Yes Local Excision No CT LR AWD 13 Matsuo [32] 2009 37 OEE No Local Excision No CT LR NR 14 Williams [33] 2009 53 CS No Local Excision No RT, CT LR DOD 15 Bourdel [34] 2010 43 CS, ESNE Yes Local Excision No RT, CT LNR DOD 16 Yan [35] 2011 41 CS, ESNE, TAH No Local Excision No None NM NR 17 Shalin [1] 2012 47 CS Yes Local Excision No RT, CT NM NR 18 Mert [12] 2012 42 CS, Oophorectomy Yes Local Excision + LND Yes CT NM NR 19 Mert [12] 2012 51 CS, TAH Yes Local Excision No RT NM NR 20 Sawazaki [36] 2012 41 CS Yes Local Excision No CT NM NR 21 Li [37] 2012 49 CS No Local Excision + LND Yes CT NM NR 22 Dobrosz [38] 2014 42 CS Yes Local Excision No None NM NR 23 Ijichi [11] 2014 60 CS Yes Local Excision No None NM NR 24 Heller [39] 2014 37 CS NA Local Excision No None LR NR 25 Liu [40] 2014 39 CS, ESNE Yes Local Excision + LND Yes CT RPD AWD 26 Aust [41] 2015 47 CS, TAH No Local Excision No CT NM NR 27 Ruiz [42] 2015 41 CS Yes Wide resection NR RT, CT LR NR 28 Ruiz [42] 2015 57 CS Yes Wide resection NR RT, CT NM NR 29 Sosa-Duran [43] 2015 45 CS Yes Local Excision No None NM NR 30 Ferrandina [10] 2016 44 CS Yes Cytoreduction Yes CT LR DOD 31 Graur [44] 2017 43 CS No Local Excision No CT NM NR 32 Wei [45] 2017 46 CS Yes Local Excision No RT NM NR 33 Marques [17] 2017 47 CS, TS Yes Local Excision No CT LR AWD 34 Gentile [46] 2017 42 CS Yes Wide resection NR CT NM NR 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 5 of 10 35 Lopes [47] 2019 48 CS Yes Local Excision + LND Yes CT NM NR 36 Behbehani [48] 2019 48 CS, TAH Yes Wide resection NR CT NM NR 37 Rolon [18] 2019 48 CS, ESNE, TAH No Local Excision No CT NM NR 38 Giannella [49] 2020 45 CS No Local Excision No RT, CT DM DOD 39 Dong Liu [4] 2022 48 CS No Wide resection NR CT NM NR 40 Bourou (present case) 2026 45 CS, LETZ, ESNE Yes Wide resection Yes CT DM SD TABLE 2: List of reported cases of abdominal wall clear cell carcinoma AWD: alive without disease, CE: co-existing endometriosis, CS: cesarean section, CT: chemotherapy, DM: distant metastases, DOD: died of disease, ESNE: endometriotic scar nodule excision, LETZ: loop excision of transformation zone, LND: lymph node dissection, LNR: lymph node recurrence, LR: local recurrence, OEE: ovarian endometrioma excision, NED: no evidence of disease, NM: not mentioned, NR: no recurrence, RPD: rapid progression of disease, RT: radiotherapy, SD: stable disease, TAH: total abdominal hysterectomy, TS: tubal sterilization The histological characteristics of malignant transformation in endometriosis of the abdominal wall are primarily represented by CCC, followed by endometrioid adenocarcinoma, serous papillary carcinoma, sarcoma, mixed types, and others [8] . Clear cell carcinoma can show histologically papillary, tubule-cystic, or solid patterns [18] . CCC is a typical histological type in renal, pancreatic, adrenal, and gynecological cancers [11] . Immunohistochemical stains can distinguish the gynecological origin of the tumor from other cancers with clear cell components. The immunostaining pattern of female reproductive tract cancers is frequently reactive with the p53 wild type [1,9] . PAX8 is also a transcription factor that is important in the formation of the Müllerian system, and it could be a useful marker for distinguishing metastatic non- mucinous ovarian cancer from other cutaneous metastases [1,18] . A swollen abdominal mass inside or close to the surgical scar is the main symptom of abdominal wall CCC [8] . Periodic or persistent abdominal pain is an additional sign [17,49] . An abscess, hematoma, hernia, dermoid tumors, sarcomas, and metastatic disease are among the potential diagnoses for an abdominal mass connected to a prior abdominal wall surgical incision [15,18] . The earliest description of CCC developing in the abdominal wall was made in 1986, and 39 cases have subsequently been recorded in the literature (Table 2 ). The average age of diagnosis was 45.7 years, and in 91.7% of cases, there was a history of cesarean section [6] . A summary of all reported cases of abdominal wall CCC is presented in Table 2 [1,4,10-12,16-18,21-49] . Appropriate imaging techniques are required for the radiological assessment of these tumors. Among imaging methods, ultrasound is the first choice in determining suspicious areas in the abdominal wall because it is an inexpensive, simple, and non-invasive procedure [8] . A cystic, solid, or mixed mass in the abdominal wall tissue on ultrasonography may indicate malignant transformation of abdominal wall endometriosis, and blood flow signals may be observed by color Doppler ultrasonography [14] . Magnetic resonance imaging can be used to determine the size and depth of the lesion [8] . Extraovarian malignant lesions caused by endometriosis, typically, appear as solid lesions with an intermediate signal strength on T1 and T2 MR images [14] . A CT scan can also detect disease infiltration into the lateral tissues, as well as the presence of distant metastases [14] . A PET-CT scan can also be utilized to assess distant metastases [8] . An excisional biopsy or fine needle aspiration (FNA) is required in order to have a histological diagnosis [14] . FNA is sometimes inconclusive because of geographical miss. Also, it is contentious, since it may cause the spread of cancer cells to the puncture site [16] . There are no specific biochemical tumor markers to identify malignant endometriosis [8] . Serum levels of CA-125, a non-specific biomarker, are elevated in both ovarian cancer and advanced endometriosis. In cases of malignant transformation, CA-125 levels have been observed to be normal to modestly increased, with a sensitivity and specificity of 87% and 92%, respectively [15,42] . Because CCC of the abdominal wall is uncommon, there is no specific International Federation of Gynecology and Obstetrics (FIGO) staging system nor established treatment protocol [8,21] . As a result, the principles of ovarian cancer staging and management are often implemented [9,50] . To reduce the size of the tumor and the difficulty of the surgery, certain authors advise the administration of induction chemotherapy prior to the surgical debulking effort. Nonetheless, the available literature indicates that neoadjuvant chemotherapy may not be very effective in patients with abdominal CCC [51] . It appears that debulking surgery is the main aspect of treatment, followed by systemic chemotherapy and immunotherapy [39] . 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 6 of 10 Wide excision of the abdominal wall with clear margins, hysterectomy, bilateral salpingo-oophorectomy, and omentectomy are the most common surgical procedures [19,52] . Lymph node dissection is included in the management when pre-operative imaging demonstrates suspicious nodes or nodal involvement [15] . A synthetic mesh and/or flap is usually used for abdominal wall reconstruction [19] . Because there are only a few publications on the abdominal CCC, there is no well-established protocol for adjuvant treatment. Adjuvant platinum-based chemotherapy appears to be the most effective treatment for clear cell carcinoma originating from abdominal wall endometriosis. Six cycles of intravenous carboplatin and paclitaxel appear to be less toxic and better tolerated than other combinations [15] . However, despite the use of adjuvant chemotherapy, disease progression or recurrence may still occur [46] . Immunotherapy, targeted therapy, and progestin therapy have also been discussed as alternative adjuvant options in the primary or recurrent setting [2,6,37] . Adjuvant radiotherapy may be considered [42] , especially in cases where chemotherapy response is suboptimal and the tumor is not amenable to complete surgical resection, but there are only a few reports indicating successful outcomes with radiotherapy, and no recommended treatment protocols are available. The prognosis of patients with endometriosis-associated clear cell carcinoma of the abdominal wall is not favorable, with a relatively high rate of recurrence after treatment [16] . This is particularly true if the carcinoma is not fully excised or if it has spread to surrounding tissues. About 26.5% of patients passed away within a year of receiving a diagnosis [9] , and the median survival appears to be, roughly, 30 months [8,9] . Lymph node metastasis, particularly in the inguinal lymph nodes, is very common [19] , since the superficial abdominal wall lymphatics flow into the superficial inguinal nodes [15] . In some cases, distant recurrences are found in the liver, lungs, neck lymph nodes, and bones [19] . Regular abdominal, pelvic, and rectal examinations, serum CA-125 levels, and imaging should all be part of the patient's follow-up in order to identify early signs of metastases [15] . Endometriosis-associated CCC of the abdominal wall usually occurs in women who have undergone some type of gynecological surgery [9] . The incidence of abdominal wall endometriosis ranges from 0.03% to 1.08% [7,39] in women after hysterectomy or cesarean section, and, according to Taburiaux et al., the average interval for malignant transformation of abdominal wall endometriosis after a gynecological surgery can be as long as 21 years [53] . According to the literature, the mean age of diagnosis is 47 years, close to the age of our 45-year-old patient [15] . Similar to what is commonly reported in the previous reports, our patient had undergone two cesarean sections, 14 and 10 years previously. Also, she had undergone excision of an abdominal wall endometriotic lesion 5 years ago. Before being referred to our Unit, the patient had undergone excision of a palpable 5x5 cm mass in the anterior abdominal wall in another hospital. The mass was gradually increasing in size over a period of 6 months, and the surgeons thought that it was a recurrence of endometriosis. The lesion was completely excised, but with very narrow margins (1 mm), and the histology showed an endometriosis-related CCC. Three months after the initial excisional biopsy, the patient proceeded to cytoreductive surgery. According to the literature, the cornerstone of treatment is wide surgical excision of the tumor combined with total hysterectomy, bilateral salpingo-oophorectomy, and omentectomy [51] . The surgery is often complemented by lymph node dissection, as lymph nodes are among the first sites where recurrence may appear [51] . Neoadjuvant chemotherapy has been used to reduce the initial tumor size, but it does not seem to have significant results [51] . In our case, the patient had a PET-CT imaging that showed hypermetabolic lesions in the anterior abdominal wall, and she underwent excision of the anterior abdominal wall, total hysterectomy, bilateral salpingo-oophorectomy, infracolic omentectomy, and removal of enlarged pelvic and para-aortic lymph nodes. Cases with a comparable medical history should always raise the suspicion of scar endometriosis and the possibility that a CCC may be harbored in these lesions. It is preferable that such surgeries are dealt with by a gynecological oncology team and appropriate presurgical imaging and discussion in a Multidisciplinary Tumor Meeting are executed. It is known that this type of carcinoma is aggressive, with a very poor prognosis and a median survival of around 30 months after the initial diagnosis [15] . However, in our case, the patient developed an unusually early recurrence of the disease after surgery, with metastatic lesions in the liver and lungs. After reviewing the preoperative imaging studies, no suspicious lesions were identified in the abdomen or chest. This finding confirms the biologically aggressive behavior of the disease. Due to the rarity of these cases, there is no clearly established systemic treatment protocol [8] ; however, according to the literature, adjuvant chemotherapy with carboplatin and paclitaxel typically follows cytoreductive surgery [8,15] . In our case, because of the early recurrence and the need for further evaluation, the patient eventually began her first treatment two months after the cytoreductive surgery. She received a combination of carboplatin, paclitaxel, and bevacizumab, an anti-vascular endothelial growth factor (anti- VEGF) agent, in six cycles of 21 days each. After this regimen, she showed a significant reduction of the disease and has been continuing maintenance therapy with bevacizumab. The patient has continued 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 7 of 10 maintenance therapy with bevacizumab and remains in stable condition 15 months following surgery.

Endometriosis-associated clear cell carcinoma of the abdominal wall remains a rare but aggressive carcinoma. The pathogenesis is thought to involve chronic inflammation, hormonal influences, and metaplastic transformation of endometrial tissue. Diagnosis is challenging, requiring a high degree of clinical suspicion, especially in patients with a history of endometriosis and abdominal wall masses. Surgical resection remains the cornerstone of treatment, but recurrence is common, and long-term surveillance is essential. Further research is needed to better understand the underlying mechanisms of carcinogenesis in endometriosis and to improve diagnostic and therapeutic strategies for this rare malignancy. In summary, while endometriosis-associated clear cell carcinoma of the abdominal wall is rare, it has to be considered in the differential diagnosis of abdominal wall masses, particularly in women with a history of endometriosis. Early detection and appropriate multidisciplinary management are crucial for improving outcomes. Additional Information Author Contributions All authors have reviewed the final version to be published and agreed to be accountable for all aspects of the work. Concept and design: Maria Zoi Bourou, Evangelia Razis, Makarios Eleftheriades, Theodoros Panoskaltsis Acquisition, analysis, or interpretation of data: Maria Zoi Bourou, Despoina Myoteri, Iakovos Vlahos, Porfyrios Korompelis, Aikaterini Stylianaki, Evangelia Razis Drafting of the manuscript: Maria Zoi Bourou, Despoina Myoteri, Iakovos Vlahos Critical review of the manuscript for important intellectual content: Maria Zoi Bourou, Porfyrios Korompelis, Aikaterini Stylianaki, Evangelia Razis, Makarios Eleftheriades, Theodoros Panoskaltsis Supervision: Theodoros Panoskaltsis Disclosures Human subjects: Informed consent for treatment and open access publication was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

1 . Shalin SC, Haws AL, Carter DG, Zarrin-Khameh N: Clear cell adenocarcinoma arising from endometriosis in abdominal wall cesarean section scar: a case report and review of the literature . J Cutan Pathol. 2012, 39:1035-41. 10.1111/j.1600-0560.2012.01982.x 2 . Lewis GK, Gajarawala SN, Robinson KE, Chen AH, Robertson MW: Clear cell adenocarcinoma arising from anterior abdominal wall cesarean section scar endometriosis treated with excision and the addition of trastuzumab for adjuvant chemotherapy: a case report . Gynecol Oncol Rep. 2022, 41:100995. 10.1016/j.gore.2022.100995 3 . Chauhan S, More A, Chauhan V, Kathane A: Endometriosis: a review of clinical diagnosis, treatment, and pathogenesis . Cureus. 2022, 14:e28864. 10.7759/cureus.28864 4 . Liu D, Wei H, Huang J, Shen H, Wang X, Hu C: Clear cell adenocarcinoma arising from endometriosis in abdominal wall cesarean section scar: a case report and literature review . Int J Womens Health. 2023, 15:25- 32. 10.2147/IJWH.S382235 5 . Ferrari F, Valenti G, Forte S, et al.: Clear cell degeneration associated with endometriosis of abdominal wall after cesarean section: a case report and systematic review of literature . J Obstet Gynaecol Res. 2021, 47:1243-52. 10.1111/jog.14635 6 . Ko YT, Wu CH, Chang CS, Lai DW, Liu TC: Successful treatment of abdominal wall advanced endometriosis- associated clear cell carcinoma with AKT pathway inhibitor: case report . Medicina (Kaunas). 2024, 60: 10.3390/medicina60121946 7 . Mihailovici A, Rottenstreich M, Kovel S, Wassermann I, Smorgick N, Vaknin Z: Endometriosis-associated malignant transformation in abdominal surgical scar: a PRISMA-compliant systematic review . Medicine (Baltimore). 2017, 96:e9136. 10.1097/MD.0000000000009136 8 . Alaert J, Lancelle M, Timmermans M, Tanos P, Nisolle M, Karampelas S: Malignancy in abdominal wall endometriosis: is there a way to avoid it? A systematic review . J Clin Med. 2024, 13: 10.3390/jcm13082282 9 . Bellalah A, Lahbecha B, Zokar O, et al.: Clear cell carcinoma of the abdominal wall: a case report with a 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 8 of 10 review of the literature . Ann Med Surg (Lond). 2022, 79:104038. 10.1016/j.amsu.2022.104038 10 . Ferrandina G, Palluzzi E, Fanfani F, et al.: Endometriosis-associated clear cell carcinoma arising in caesarean section scar: a case report and review of the literature . World J Surg Oncol. 2016, 14:300. 10.1186/s12957-016-1054-7 11 . Ijichi S, Mori T, Suganuma I, et al.: Clear cell carcinoma arising from cesarean section scar endometriosis: case report and review of the literature . Case Rep Obstet Gynecol. 2014, 2014:642483. 10.1155/2014/642483 12 . Mert I, Semaan A, Kim S, Ali-Fehmi R, Morris RT: Clear cell carcinoma arising in the abdominal wall: two case reports and literature review . Am J Obstet Gynecol. 2012, 207:e7-9. 10.1016/j.ajog.2012.05.029 13 . Petit C, Donval L, Chandeze MM, Chis C, Joste M, Panel P: Surgery of abdominal wall endometriosis associated with clear-cell carcinoma: case report and review . J Gynecol Obstet Hum Reprod. 2023, 52:102561. 10.1016/j.jogoh.2023.102561 14 . Liu G, Wang Y, Chen Y, Ren F: Malignant transformation of abdominal wall endometriosis: a systematic review of the epidemiology, diagnosis, treatment, and outcomes . Eur J Obstet Gynecol Reprod Biol. 2021, 264:363-7. 10.1016/j.ejogrb.2021.08.006 15 . Bahall V, De Barry L, Rampersad A: Clear cell carcinoma arising from abdominal wall endometriosis-a report on two cases and literature review . World J Surg Oncol. 2022, 20:86. 10.1186/s12957-022-02553-x 16 . Bats AS, Zafrani Y, Pautier P, Duvillard P, Morice P: Malignant transformation of abdominal wall endometriosis to clear cell carcinoma: case report and review of the literature . Fertil Steril. 2008, 90:1197.e13-6. 10.1016/j.fertnstert.2007.08.080 17 . Marques C, Silva TS, Dias MF: Clear cell carcinoma arising from abdominal wall endometriosis - brief report and review of the literature . Gynecol Oncol Rep. 2017, 20:78-80. 10.1016/j.gore.2017.03.008 18 . Rivera Rolon MD, Allen D, Richardson G, Clement C: Abdominal wall clear cell carcinoma: case report of a rare event with potential diagnostic difficulties . Case Rep Pathol. 2019, 2019:1695734. 10.1155/2019/1695734 19 . Lai YL, Hsu HC, Kuo KT, Chen YL, Chen CA, Cheng WF: Clear cell carcinoma of the abdominal wall as a rare complication of general obstetric and gynecologic surgeries: 15 years of experience at a large academic institution . Int J Environ Res Public Health. 2019, 16: 10.3390/ijerph16040552 20 . Scott RB: Malignant changes in endometriosis . Obstet Gynecol. 1953, 2:283-9. 21 . Schnieber D, Wagner-Kolb D: [Malignant transformation of extragenital endometriosis] . Geburtshilfe Frauenheilkd. 1986, 46:658-9. 10.1055/s-2008-1036277 22 . Hitti IF, Glasberg SS, Lubicz S: Clear cell carcinoma arising in extraovarian endometriosis: report of three cases and review of the literature . Gynecol Oncol. 1990, 39:314-320. 10.1016/0090-8258(90)90259-n 23 . Miller DM, Schouls JJ, Ehlen TG: Clear cell carcinoma arising in extragonadal endometriosis in a caesarean section scar during pregnancy . Gynecol Oncol. 1998, 70:127-30. 10.1006/gyno.1998.4989 24 . Park SW, Hong SM, Wu HG, Ha SW: Clear cell carcinoma arising in a cesarean section scar endometriosis: a case report . J Korean Med Sci. 1999, 14:217-9. 10.3346/jkms.1999.14.2.217 25 . Ishida GM, Motoyama T, Watanabe T, Emura I: Clear cell carcinoma arising in a cesarean section scar. Report of a case with fine needle aspiration cytology . Acta Cytol. 2003, 47:1095-8. 10.1159/000326655 26 . Sergent F, Baron M, Le Cornec JB, Scotté M, Mace P, Marpeau L: Transformation maligne d'une endométriose pariétale [Malignant transformation of abdominal wall endometriosis: a new case report] . J Gynecol Obstet Biol Reprod (Paris). 2006, 35:186-90. 10.1016/s0368-2315(06)76394-3 27 . Alberto VO, Lynch M, Labbei FN, Jeffers M: Primary abdominal wall clear cell carcinoma arising in a caesarean section scar endometriosis . Ir J Med Sci. 2006, 175:69-71. 10.1007/BF03169006 28 . Razzouk K, Roman H, Chanavaz-Lacheray I, Scotté M, Verspyck E, Marpeau L: Mixed clear cell and endometrioid carcinoma arising in parietal endometriosis . Gynecol Obstet Invest. 2007, 63:140-2. 10.1159/000096437 29 . Harry VN, Shanbhag S, Lyall M, Narayansingh GV, Parkin DE: Isolated clear cell adenocarcinoma in scar endometriosis mimicking an incisional hernia . Obstet Gynecol. 2007, 110:469-71. 10.1097/01.AOG.0000260393.46154.5f 30 . Rust MM, Susa J, Naylor R, Cavuoti D: Clear cell carcinoma in a background of endometriosis. Case report of a finding in a midline abdominal scar 5 years after a total abdominal hysterectomy . Acta Cytol. 2008, 52:475-80. 10.1159/000325557 31 . Achach T, Rammeh S, Trabelsi A, Ltaief R, Ben Abdelkrim S, Mokni M, Korbi S: Clear cell adenocarcinoma arising from abdominal wall endometriosis . J Oncol. 2008, 2008:478325. 10.1155/2008/478325 32 . Matsuo K, Alonsozana EL, Eno ML, Rosenshein NB, Im DD: Primary peritoneal clear cell adenocarcinoma arising in previous abdominal scar for endometriosis surgery . Arch Gynecol Obstet. 2009, 280:637-41. 10.1007/s00404-009-0962-y 33 . Williams C, Petignat P, Belisle A, Drouin P: Primary abdominal wall clear cell carcinoma: case report and review of literature . Anticancer Res. 2009, 29:1591-3. 34 . Bourdel N, Durand M, Gimbergues P, Dauplat J, Canis M: Exclusive nodal recurrence after treatment of degenerated parietal endometriosis . Fertil Steril. 2010, 93:2074.e1-6. 10.1016/j.fertnstert.2009.11.004 35 . Yan Y, Li L, Guo J, Zheng Y, Liu Q: Malignant transformation of an endometriotic lesion derived from an abdominal wall scar . Int J Gynaecol Obstet. 2011, 115:202-3. 10.1016/j.ijgo.2011.06.018 36 . Sawazaki H, Goto H, Takao N, Taki Y, Takeuchi H: Clear cell adenocarcinoma arising from abdominal wall endometriosis mimicking urachal tumor . Urology. 2012, 79:e84-5. 10.1016/j.urology.2011.02.034 37 . Li X, Yang J, Cao D, Lang J, Chen J, Shen K: Clear-cell carcinoma of the abdominal wall after cesarean delivery . Obstet Gynecol. 2012, 120:445-8. 10.1097/AOG.0b013e31824da6fe 38 . Dobrosz Z, Paleń P, Stojko R, Właszczuk P, Niesłuchowska-Hoxha A, Piechuta-Kośmider I.: Clear cell carcinoma derived from an endometriosis focus in a scar after a caesarean section-a case report and literature review . Ginekol Pol. 2014, 85:792-5. 10.17772/gp/1683 39 . Heller DS, Houck K, Lee ES, Granick MS: Clear cell adenocarcinoma of the abdominal wall: a case report . J Reprod Med. 2014, 59:330-2. 40 . Liu H, Leng J, Lang J, Cui Q: Clear cell carcinoma arising from abdominal wall endometriosis: a unique case with bladder and lymph node metastasis . World J Surg Oncol. 2014, 12:51. 10.1186/1477-7819-12-51 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 9 of 10 41 . Aust S, Tiringer D, Grimm C, Stani J, Langer M: Therapy of a clear cell adenocarcinoma of unknown primary arising in the abdominal wall after cesarean section and after hysterectomy . Wien Klin Wochenschr. 2015, 127:62-4. 10.1007/s00508-014-0619-0 42 . Ruiz MP, Wallace DL, Connell MT: Transformation of abdominal wall endometriosis to clear cell carcinoma . Case Rep Obstet Gynecol. 2015, 2015:123740. 10.1155/2015/123740 43 . Sosa-Durán EE, Aboharp-Hasan Z, Mendoza-Morales RC, García-Rodríguez FM, Jiménez-Villanueva X, Peñavera-Hernández JR: [Clear cell adenocarcinoma arising from abdominal wall endometriosis] . Cir Cir. 2016, 84:245-9. 10.1016/j.circir.2015.06.024 44 . Graur F, Mois E, Elisei R, Furcea L, Dragota M, Zaharie T, Al Hajjar N: Malignant endometriosis of the abdominal wall . Ann Ital Chir. 2017, 6: 45 . Wei CJ, Huang SH: Clear cell carcinoma arising from scar endometriosis: a case report and literature review . Tzu Chi Med J. 2017, 29:55-8. 10.4103/tcmj.tcmj_11_17 46 . Gentile JK, Migliore R, Kistenmacker FJ, et al.: Malignant transformation of abdominal wall endometriosis to clear cell carcinoma: case report . Sao Paulo Med J. 2018, 136:586-90. 10.1590/1516- 3180.2017.0103300417 47 . Lopes A, Anton C, Slomovitz BM, Accardo de Mattos L, Marino Carvalho F: Clear cell carcinoma arising from abdominal wall endometrioma after cesarean section . Int J Gynecol Cancer. 2019, 29:1332-5. 10.1136/ijgc- 2019-000808 48 . Behbehani S, Magtibay P, Chen L, Wasson M: Clear cell carcinoma of the anterior abdominal wall secondary to iatrogenic endometriosis . J Minim Invasive Gynecol. 2020, 27:1230-1. 10.1016/j.jmig.2019.12.016 49 . Giannella L, Serri M, Maccaroni E, et al.: Endometriosis-associated clear cell carcinoma of the abdominal wall after caesarean section: a case report and review of the literature . In Vivo. 2020, 34:2147-52. 10.21873/invivo.12021 50 . Hashemi SR, Morshedi M, Maghsoudi H, Esmailzadeh A, Alkatout I: Clear-cell carcinoma originating from cesarean section scar: two case reports . J Med Case Rep. 2021, 15:146. 10.1186/s13256-021-02775-9 51 . Feng Z, Wen H, Ju X, Bi R, Chen X, Yang W, Wu X: Treatment for clear cell carcinoma of the abdominal wall at a tertiary cancer center . Sci Rep. 2022, 12:10820. 10.1038/s41598-022-14917-0 52 . Colarossi C, Picardo MC, Colarossi L, et al.: Clear cell carcinoma arising in an abdominal wall cesarean section scar: a case report with description of pathological and molecular features . Front Surg. 2021, 8:735381. 10.3389/fsurg.2021.735381 53 . Taburiaux L, Pluchino N, Petignat P, Wenger JM: Endometriosis-associated abdominal wall cancer: a poor prognosis? . Int J Gynecol Cancer. 2015, 25:1633-8. 10.1097/IGC.0000000000000556 2026 Bourou et al. Cureus 18(7): e112058. DOI 10.7759/cureus.112058 10 of 10