Giant Endometrioma of the Canal of Nuck Mimicking a Vulvar Mass: A Rare Case and Narrative Review

Giant Endometrioma of the Canal of Nuck Mimicking a Vulvar Mass: A Rare Case and Narrative Review | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Giant Endometrioma of the Canal of Nuck Mimicking a Vulvar Mass: A Rare Case and Narrative Review Lateefa O. Aldakhil This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9075998/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 19 You are reading this latest preprint version Abstract Background: Endometriosis of the canal of Nuck is an extremely rare manifestation of extrapelvic endometriosis that may mimic common groin pathologies such as inguinal hernia or hydrocele, often leading to diagnostic difficulty and delayed recognition. Case Presentation: We report the case of a 29-year-old nulliparous woman who presented with a gradually enlarging painless swelling in the right vulvar region over eight months. Physical examination revealed a large cystic mass measuring approximately 15 × 10 cm involving the right vulva and inguinal area with displacement of the clitoris and vaginal introitus. Ultrasonography demonstrated a well-defined cystic lesion with internal echoes, while magnetic resonance imaging revealed a hemorrhagic cystic lesion along the course of the canal of Nuck without peritoneal communication. Surgical exploration identified a cystic mass adjacent to the round ligament containing characteristic “chocolate-like” fluid. Complete excision of the lesion was performed. Histopathological examination confirmed endometrioma of the canal of Nuck. The postoperative course was uneventful, and the patient remained asymptomatic with no evidence of recurrence during three years of follow-up. Conclusion: Although rare, canal of Nuck endometriosis should be considered in the differential diagnosis of inguinal or vulvar masses in women of reproductive age. Early recognition with appropriate imaging and complete surgical excision allows accurate diagnosis and excellent outcomes. To our knowledge, this case represents one of the largest canal of Nuck endometriomas reported in the literature and highlights the diagnostic challenges posed by atypical presentations without cyclic symptoms. Canal of Nuck endometriosis endometrioma vulvar swelling hydrocele case report Figures Figure 1 Figure 2 Background Groin and vulvar swellings in women represent a broad diagnostic spectrum that includes inguinal hernia, Bartholin gland cyst, epidermoid cyst, lymphangioma, and hydrocele of the canal of Nuck. These conditions often present as painless cystic masses, making accurate preoperative diagnosis challenging and frequently leading to misdiagnosis and inappropriate management [ 1 – 3 ]. Endometriosis is defined as the presence of functional endometrial glands and stroma outside the uterine cavity and affects approximately 10–15% of women of reproductive age. The disease most commonly involves pelvic structures such as the ovaries, pelvic peritoneum, and uterosacral ligaments [ 4 ]. Extrapelvic endometriosis is uncommon and includes rare involvement of the inguinal region and canal of Nuck [ 5 ]. The canal of Nuck is an embryological peritoneal extension that accompanies the round ligament through the inguinal canal into the labia majora and represents the female analogue of the processus vaginalis. Failure of obliteration of this structure may result in cyst formation or create a potential space for ectopic implantation of endometrial tissue [ 6 – 7 ]. Endometriosis involving the canal of Nuck is exceptionally rare, with fewer than 50 cases reported worldwide, and is frequently misdiagnosed as inguinal hernia or hydrocele due to overlapping clinical features [ 4 , 8 ]. A systematic review by Prodromidou et al. identified 36 reported cases of canal of Nuck endometriosis, with a median age of 36 years and a marked right-sided predominance (83%). Most patients presented with a painless or mildly tender groin mass, while cyclic pain related to menstruation was reported in only a minority of cases. Surgical excision was the primary treatment modality, and rare cases of malignant transformation have been reported [ 5 ]. Subsequent case reports and small series have confirmed the rarity of this condition and highlighted the diagnostic value of ultrasonography and magnetic resonance imaging (MRI) in differentiating canal of Nuck endometriosis from more common groin pathologies [ 8 – 13 ]. A summary of previously reported cases is provided in Table 1 . Clinically, canal of Nuck endometriosis may present with cyclic or non-cyclic groin or vulvar swelling, and atypical presentations can delay diagnosis and lead to unnecessary procedures [ 8 , 13 ]. MRI is considered the imaging modality of choice because it can identify hemorrhagic components and delineate the relationship of the lesion to the round ligament and peritoneal cavity, although histopathological examination remains the gold standard for definitive diagnosis [ 8 – 12 ]. In this report, we describe a rare case of a giant endometrioma of the canal of Nuck presenting as a vulvar mass without cyclic symptoms, highlighting the diagnostic challenges, surgical management, and clinical implications, and we provide a narrative review of the existing literature. Table 1 Summary of Published Cases of Canal of Nuck Endometriosis Author Year Type of Study Age (years) Side Clinical Presentation Imaging Modality Treatment Outcome Wang et al. 4 2009 Case report 39 Right Groin mass with cyclic pain US, MRI Surgical excision No recurrence Prodromidou et al. 10 2020 Systematic review Median 36 Mostly Right (83%) Groin mass ± cyclic pain US/MRI Surgical excision Rare recurrence; 14% malignant transformation Kohlhauser et al. 13 2018 Case report 35 Right Inguinal swelling Ultrasound Surgical excision Good outcome Hwang et al 5 . 2022 Case report 33 Right Painful groin lump MRI Surgical excision No recurrence Tilva et al. 1 2023 Case report 29 Left Inguinal cystic swelling Ultrasound Surgical excision Good recovery Papadoliopoulou et al. 6 2024 Case report 31 Right Groin mass after IVF MRI Surgical excision No recurrence Lukanova et al. 9 2024 Case report 27 Right Groin swelling Ultrasound Surgical excision Good outcome Medić et al. 11 2024 Case report / Case series 40 Right Inguinal mass MRI Surgical excision No recurrence Present case 2026 Case report 29 Right Giant vulvar mass without cyclic pain Ultrasound, MRI Surgical excision No recurrence Case Presentation A 29-year-old nulliparous divorced woman presented with an eight-month history of a gradually enlarging, painless swelling of the right vulva. She denied trauma, discharge, or systemic symptoms, and there was no change in size during menstruation. Her past medical and surgical history was unremarkable. On examination, a well-defined, tense, cystic mass measuring approximately 15 × 8 cm was noted in the right vulvar and inguinal region. The lesion involved the labia majora and minora and displaced the clitoris and vaginal orifice toward the right side. The overlying skin was intact and non-tender, and there was no cough impulse or reducibility. Inguinal lymph nodes were not palpable Fig. 1 a, 1 b and 1 c. Figure 1 A. Clinical photograph showing a large cystic swelling in the right vulvar region (preoperative). Figure 1 C. The mass displacing the labia minora, clitoris, and vaginal introitus to the right. Ultrasound revealed a well-circumscribed cystic lesion with internal low-level echoes measuring 15 × 10 cm. MRI showed a hyperintense lesion on T1- and T2-weighted images without peritoneal communication, consistent with a hemorrhagic cyst. Under spinal anesthesia, a 2–3 cm oblique inguinal incision was made parallel and superior to the inguinal ligament over the palpable swelling. Subcutaneous tissue and Scarpa’s fascia were divided to expose the external oblique aponeurosis, and the superficial inguinal ring was identified. The round ligament was isolated, and the cystic lesion was found anteromedial to the round ligament within the inguinal canal. The cyst contained brownish “chocolate-like” fluid. The lesion was carefully dissected from surrounding tissues, and its proximal end was traced toward the deep inguinal ring to assess communication with the peritoneal cavity. No peritoneal communication was identified, confirming a non-communicating (encysted) lesion (Fig. 2 ). Histopathology revealed endometrial glands and stroma with areas of hemorrhage and hemosiderin-laden macrophages, confirming endometrioma (endometrial cyst) of the canal of Nuck. The patient recovered uneventfully and was discharged on the second postoperative day. At six-month follow-up, there was no recurrence. The postoperative course was uneventful. The patient remained asymptomatic and free of recurrence over a three-year follow-up period, as verified by serial clinical examinations and ultrasonographic evaluations. Discussion Endometriosis of the canal of Nuck is an extremely rare form of extrapelvic endometriosis and is often misdiagnosed as more common groin pathologies such as inguinal hernia or hydrocele. It predominantly affects women of reproductive age and may occur with or without concomitant pelvic endometriosis. Because most patients present with a groin or vulvar mass, preoperative diagnosis remains challenging, and many cases are initially managed as presumed hernias or cystic lesions [ 4 , 8 ]. The canal of Nuck is an embryological peritoneal extension that accompanies the round ligament through the inguinal canal into the labia majora. Failure of obliteration of this structure may result in cyst formation and may provide a potential space for ectopic implantation of endometrial tissue. Several pathogenetic mechanisms have been proposed, including retrograde menstruation, coelomic metaplasia, and lymphovascular dissemination [ 6 – 7 ]. A marked right-sided predominance has been consistently reported in the literature, possibly due to the protective effect of the sigmoid colon on the left side, reducing peritoneal reflux and implantation [ 5 ]. A systematic review by Prodromidou et al. identified 36 reported cases of canal of Nuck endometriosis, with a median age of 36 years and right-sided involvement in approximately 83% of cases. Most patients presented with a painless or mildly tender groin mass, while cyclic pain was reported in only a minority of cases. Surgical excision was the primary treatment modality, and recurrence after complete resection was rare [ 5 ]. Subsequent case reports and small series have confirmed the rarity of this condition and emphasized the diagnostic value of ultrasonography and magnetic resonance imaging (MRI) in differentiating canal of Nuck endometriosis from more common groin pathologies [ 8 – 13 ]. A summary of previously reported cases, including the present case, is provided in Table 1 . In the present case, the lesion was non-communicating (encysted) and showed no peritoneal communication, consistent with most reported canal of Nuck endometriomas. Non-communicating lesions can be managed with simple surgical excision, whereas communicating lesions may require high ligation of the processus vaginalis and hernia repair to prevent recurrence [ 2 , 3 ]. This distinction is clinically relevant for surgical planning and intraoperative decision-making. Our case is notable for several uncommon features. First, the lesion was exceptionally large, measuring approximately 15 cm and causing significant vulvar displacement, which is rarely described in the literature. Second, the patient had no cyclic pain, an atypical presentation that can delay diagnosis. Although cyclic pain is considered suggestive of endometriosis, most reported canal of Nuck endometriosis cases present as painless groin masses, and the absence of cyclic symptoms does not exclude the diagnosis [ 5 , 14 ]. These features highlight the diagnostic challenges and the importance of maintaining a high index of suspicion in women presenting with vulvar or inguinal masses. MRI played a crucial role in preoperative evaluation by identifying hemorrhagic components and delineating the relationship of the lesion to the round ligament and peritoneal cavity [ 8 – 12 ]. Nevertheless, histopathological examination remains the gold standard for definitive diagnosis. Complete surgical excision was curative in our patient, with no recurrence observed during three years of follow-up, consistent with previously reported outcomes showing low recurrence rates after complete resection [ 5 , 14 ]. Overall, this case underscores the importance of considering canal of Nuck endometriosis in the differential diagnosis of female groin or vulvar masses, even in the absence of cyclic pain. Early recognition, appropriate imaging, and complete surgical excision are essential for accurate diagnosis and optimal outcomes. Abbreviations • MRI Magnetic resonance imaging • US Ultrasonography • IVF In vitro fertilization Declarations Ethics approval and consent to participate Ethical approval for this study was obtained from the Institutional Review Board of King Saud University Medical City. The study was conducted in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from the patient for participation. Consent for publication Written informed consent for publication of this case report and any accompanying images was obtained from the patient. Availability of data and materials No, I do not have any research data outside the submitted manuscript file. Competing interests No, I declare that the authors have no competing interests as defined by BMC, or other interests that might be perceived to influence the results and/or discussion reported in this paper. Funding This research did not receive funding. Authors’ contributions L.A. was solely responsible for the conception and design of the case report, acquisition and interpretation of clinical data, drafting and critical revision of the manuscript, and approval of the final version for publication. The author agrees to be accountable for all aspects of the work. Acknowledgements None. References Tilva H, Tayade S, Kanjiya A. Contemporary Review of Masses in the Canal of Nuck. Cureus. 2023;15(3):e36722. 10.7759/cureus.36722 . Patnam V, Narayanan R, Kudva A. A cautionary approach to adult female groin swelling: hydrocoele of the canal of Nuck with a review of the literature. BMJ Case Rep. 2016;2016:bcr2015212547. 10.1136/bcr-2015-212547 . Lohourou GF, Kpangni AJB, Adoubs BC, Traoré I, Bony UC, Traoré AM, et al. Hydrocele of the Nuck canal. J Pediatr Surg Case Rep. 2023;89:102502. 10.1016/j.epsc.2022.102502 . Wang CJ, Chao AS, Wang TH, Wu CT, Chao A, Lai CH. Challenge in the management of endometriosis in the canal of Nuck. Fertil Steril. 2009;91(3):e9369–93611. 10.1016/j.fertnstert.2008.07.1713 . Prodromidou A, Pandraklakis A, Rodolakis A, Thomakos N. Endometriosis of the Canal of Nuck: A Systematic Review of the Literature. Diagnostics (Basel). 2020;11(1):3. 10.3390/diagnostics11010003 . Kohlhauser M, Pirsch JV, Maier T, Viertler C, Fegerl R. The Cyst of the Canal of Nuck: Anatomy, Diagnostic and Treatment of a Very Rare Diagnosis-A Case Report of an Adult Woman and Narrative Review of the Literature. Med (Kaunas). 2022;58(10):1353. 10.3390/medicina58101353 . Nasser H, King M, Rosenberg HK, Rosen A, Wilck E, Simpson WL. Anatomy and pathology of the canal of Nuck. Clin Imaging 2018 Sep-Oct;51:83–92. 10.1016/j.clinimag.2018.02.003 Hwang B, Bultitude J, Diab J, Bean A. Cyst and endometriosis of the canal of Nuck: rare differentials for a female groin mass. J Surg Case Rep. 2022;2022(1):rjab626. 10.1093/jscr/rjab626 . Papadoliopoulou M, Margaris I, Giannakis A, Samaras MG, Michalopoulos NV, Kokoropoulos P, Panayiotides I, Arkadopoulos N. Nuck Canal Endometriosis Following IVF Attempts in a Young Patient-Report of a Case. Clin Pract. 2024;14(4):1245–50. 10.3390/clinpract14040100 . Karam K, Azizi L, Azizi M, Dabaj E. Going Against the Grain: A Case Report of an Endometriosis in the Canal of Nuck. Eur J Case Rep Intern Med. 2024;11(12):005024. 10.12890/2024_005024 . Nimodia D, Parihar P, Banode P, Dudhe SS, Desale P, Gaur S. Hidden Depths: Unveiling Endometriosis in the Canal of Nuck. Cureus. 2024;16(7):e64975. 10.7759/cureus.64975 . Prodromidou A, Paspala A, Schizas D, Spartalis E, Nastos C, Machairas N. Cyst of the Canal of Nuck in adult females: A case report and systematic review. Biomed Rep. 2020;12(6):333–8. 10.3892/br.2020.1295 . Rchidi J, Kallel Y, Laamiri G, Alouani H, Bouassida M, Touinsi H. Canal of Nuck cyst in adulthood: A rare differential for inguinal masses - A case report. Int J Surg Case Rep. 2025;133:111568. 10.1016/j.ijscr.2025.111568 . Medić F, Pavlović M, Bekavac Vlatković I, Rašić F, Jug-Klobučić A. Endometriosis of the canal of Nuck: diagnosis and treatment. Arch Gynecol Obstet. 2024;310(4):2265–6. 10.1007/s00404-024-07711-y . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 03 Apr, 2026 Reviewers agreed at journal 03 Apr, 2026 Reviews received at journal 01 Apr, 2026 Reviews received at journal 01 Apr, 2026 Reviews received at journal 01 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviewers agreed at journal 31 Mar, 2026 Reviewers agreed at journal 31 Mar, 2026 Reviewers agreed at journal 30 Mar, 2026 Reviews received at journal 30 Mar, 2026 Reviewers agreed at journal 30 Mar, 2026 Reviews received at journal 29 Mar, 2026 Reviewers agreed at journal 29 Mar, 2026 Reviewers agreed at journal 29 Mar, 2026 Reviewers invited by journal 29 Mar, 2026 Editor assigned by journal 29 Mar, 2026 Editor invited by journal 16 Mar, 2026 Submission checks completed at journal 13 Mar, 2026 First submitted to journal 12 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9075998","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":616104100,"identity":"7c49149e-a725-4226-ad4c-cc804933d9da","order_by":0,"name":"Lateefa O. Aldakhil","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4klEQVRIiWNgGAWjYBACAzBpwyBn394DZvLwEdbCDCTTGIwNeM4wMBwAamEjVkviBokcsBYGwlrYzx988CHBLnG75NuDjz/m2MmwMTA/fHQDnxaeZGbDGQnJxjtn5yUbHNyWDHQYm7FxDl6HJbNJ8/5glm24nWMmcXAbM1ALD5s0Xi38j9l//0moZ2y4eQakpZ4ILRLJbMwMCYcVN9zgAWk5TIyWx8aSPQnHgUSOscHZbcd52JgJ+MW+P/Hhhx8J1XL87GcMH1Ruq7bnZ29++BifFiyAmTTlo2AUjIJRMAqwAACL4ETkQ/7UwQAAAABJRU5ErkJggg==","orcid":"","institution":"King Saud University Medical City, King Saud University","correspondingAuthor":true,"prefix":"","firstName":"Lateefa","middleName":"O.","lastName":"Aldakhil","suffix":""}],"badges":[],"createdAt":"2026-03-09 18:08:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9075998/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9075998/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106068829,"identity":"8019553b-961a-487a-83d2-adc5b23b3729","added_by":"auto","created_at":"2026-04-03 06:20:58","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":416644,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA. Clinical photograph showing a large cystic swelling in the right vulvar region (preoperative).\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB. Measurement of the lesion demonstrating approximately 15 ×10 cm.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eC. The mass displacing the labia minora, clitoris, and vaginal introitus to the right.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9075998/v1/e31db0141b33ece5e24faf8d.png"},{"id":106068830,"identity":"76e04e2b-5847-4aa5-a92c-91b39fc1d339","added_by":"auto","created_at":"2026-04-03 06:20:58","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":688780,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eIntraoperative image showing complete excision of the cystic mass.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9075998/v1/9d0569ff5733cd51d4ccb4ea.jpeg"},{"id":106094758,"identity":"a525e643-4522-4cc8-a03d-2f65a988e2bd","added_by":"auto","created_at":"2026-04-03 11:43:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1952250,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9075998/v1/5d78f1a4-964b-46b5-98ef-eb78aec9e551.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Giant Endometrioma of the Canal of Nuck Mimicking a Vulvar Mass: A Rare Case and Narrative Review","fulltext":[{"header":"Background","content":"\u003cp\u003eGroin and vulvar swellings in women represent a broad diagnostic spectrum that includes inguinal hernia, Bartholin gland cyst, epidermoid cyst, lymphangioma, and hydrocele of the canal of Nuck. These conditions often present as painless cystic masses, making accurate preoperative diagnosis challenging and frequently leading to misdiagnosis and inappropriate management [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Endometriosis is defined as the presence of functional endometrial glands and stroma outside the uterine cavity and affects approximately 10\u0026ndash;15% of women of reproductive age. The disease most commonly involves pelvic structures such as the ovaries, pelvic peritoneum, and uterosacral ligaments [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Extrapelvic endometriosis is uncommon and includes rare involvement of the inguinal region and canal of Nuck [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The canal of Nuck is an embryological peritoneal extension that accompanies the round ligament through the inguinal canal into the labia majora and represents the female analogue of the processus vaginalis. Failure of obliteration of this structure may result in cyst formation or create a potential space for ectopic implantation of endometrial tissue [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Endometriosis involving the canal of Nuck is exceptionally rare, with fewer than 50 cases reported worldwide, and is frequently misdiagnosed as inguinal hernia or hydrocele due to overlapping clinical features [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. A systematic review by Prodromidou et al. identified 36 reported cases of canal of Nuck endometriosis, with a median age of 36 years and a marked right-sided predominance (83%). Most patients presented with a painless or mildly tender groin mass, while cyclic pain related to menstruation was reported in only a minority of cases. Surgical excision was the primary treatment modality, and rare cases of malignant transformation have been reported [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Subsequent case reports and small series have confirmed the rarity of this condition and highlighted the diagnostic value of ultrasonography and magnetic resonance imaging (MRI) in differentiating canal of Nuck endometriosis from more common groin pathologies [\u003cspan additionalcitationids=\"CR9 CR10 CR11 CR12\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. A summary of previously reported cases is provided in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Clinically, canal of Nuck endometriosis may present with cyclic or non-cyclic groin or vulvar swelling, and atypical presentations can delay diagnosis and lead to unnecessary procedures [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. MRI is considered the imaging modality of choice because it can identify hemorrhagic components and delineate the relationship of the lesion to the round ligament and peritoneal cavity, although histopathological examination remains the gold standard for definitive diagnosis [\u003cspan additionalcitationids=\"CR9 CR10 CR11\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this report, we describe a rare case of a giant endometrioma of the canal of Nuck presenting as a vulvar mass without cyclic symptoms, highlighting the diagnostic challenges, surgical management, and clinical implications, and we provide a narrative review of the existing literature.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of Published Cases of Canal of Nuck Endometriosis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAuthor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYear\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eType of Study\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSide\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eClinical Presentation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eImaging Modality\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eTreatment\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eOutcome\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWang et al.\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGroin mass with cyclic pain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUS, MRI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eNo recurrence\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProdromidou et al.\u003csup\u003e10\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSystematic review\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMedian 36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMostly Right (83%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGroin mass\u0026thinsp;\u0026plusmn;\u0026thinsp;cyclic pain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUS/MRI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eRare recurrence; 14% malignant transformation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKohlhauser et al.\u003csup\u003e13\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eInguinal swelling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUltrasound\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eGood outcome\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHwang et al\u003csup\u003e5\u003c/sup\u003e.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2022\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePainful groin lump\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMRI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eNo recurrence\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTilva et al.\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2023\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLeft\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eInguinal cystic swelling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUltrasound\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eGood recovery\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePapadoliopoulou et al.\u003csup\u003e6\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2024\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGroin mass after IVF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMRI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eNo recurrence\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLukanova et al.\u003csup\u003e9\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2024\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGroin swelling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUltrasound\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eGood outcome\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedić et al.\u003csup\u003e11\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2024\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report / Case series\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eInguinal mass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMRI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eNo recurrence\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePresent case\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCase report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGiant vulvar mass without cyclic pain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eUltrasound, MRI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSurgical excision\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eNo recurrence\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA 29-year-old nulliparous divorced woman presented with an eight-month history of a gradually enlarging, painless swelling of the right vulva. She denied trauma, discharge, or systemic symptoms, and there was no change in size during menstruation. Her past medical and surgical history was unremarkable. On examination, a well-defined, tense, cystic mass measuring approximately 15 \u0026times; 8 cm was noted in the right vulvar and inguinal region. The lesion involved the labia majora and minora and displaced the clitoris and vaginal orifice toward the right side. The overlying skin was intact and non-tender, and there was no cough impulse or reducibility. Inguinal lymph nodes were not palpable Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb and \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec.\u003c/p\u003e \u003cp\u003e \u003cdiv description=\"C:\\Users\\PC\\Desktop\\surgey\\Figure 1a.jpg\" class=\"Drawing\" id=\"1\" name=\"Picture 1\"\u003e\u003c/div\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA. \u003cb\u003eClinical photograph showing a large cystic swelling in the right vulvar region (preoperative).\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv description=\"C:\\Users\\PC\\Desktop\\surgey\\Figure 1b.jpg\" class=\"Drawing\" id=\"2\" name=\"Picture 2\"\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC. \u003cb\u003eThe mass displacing the labia minora, clitoris, and vaginal introitus to the right.\u003c/b\u003e\u003c/p\u003e \u003cp\u003eUltrasound revealed a well-circumscribed cystic lesion with internal low-level echoes measuring 15 \u0026times; 10 cm. MRI showed a hyperintense lesion on T1- and T2-weighted images without peritoneal communication, consistent with a hemorrhagic cyst.\u003c/p\u003e \u003cp\u003eUnder spinal anesthesia, a 2\u0026ndash;3 cm oblique inguinal incision was made parallel and superior to the inguinal ligament over the palpable swelling. Subcutaneous tissue and Scarpa\u0026rsquo;s fascia were divided to expose the external oblique aponeurosis, and the superficial inguinal ring was identified. The round ligament was isolated, and the cystic lesion was found anteromedial to the round ligament within the inguinal canal. The cyst contained brownish \u0026ldquo;chocolate-like\u0026rdquo; fluid. The lesion was carefully dissected from surrounding tissues, and its proximal end was traced toward the deep inguinal ring to assess communication with the peritoneal cavity. No peritoneal communication was identified, confirming a non-communicating (encysted) lesion (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHistopathology revealed endometrial glands and stroma with areas of hemorrhage and hemosiderin-laden macrophages, confirming endometrioma (endometrial cyst) of the canal of Nuck. The patient recovered uneventfully and was discharged on the second postoperative day. At six-month follow-up, there was no recurrence. The postoperative course was uneventful. The patient remained asymptomatic and free of recurrence over a three-year follow-up period, as verified by serial clinical examinations and ultrasonographic evaluations.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eEndometriosis of the canal of Nuck is an extremely rare form of extrapelvic endometriosis and is often misdiagnosed as more common groin pathologies such as inguinal hernia or hydrocele. It predominantly affects women of reproductive age and may occur with or without concomitant pelvic endometriosis. Because most patients present with a groin or vulvar mass, preoperative diagnosis remains challenging, and many cases are initially managed as presumed hernias or cystic lesions [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe canal of Nuck is an embryological peritoneal extension that accompanies the round ligament through the inguinal canal into the labia majora. Failure of obliteration of this structure may result in cyst formation and may provide a potential space for ectopic implantation of endometrial tissue. Several pathogenetic mechanisms have been proposed, including retrograde menstruation, coelomic metaplasia, and lymphovascular dissemination [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. A marked right-sided predominance has been consistently reported in the literature, possibly due to the protective effect of the sigmoid colon on the left side, reducing peritoneal reflux and implantation [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA systematic review by Prodromidou et al. identified 36 reported cases of canal of Nuck endometriosis, with a median age of 36 years and right-sided involvement in approximately 83% of cases. Most patients presented with a painless or mildly tender groin mass, while cyclic pain was reported in only a minority of cases. Surgical excision was the primary treatment modality, and recurrence after complete resection was rare [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Subsequent case reports and small series have confirmed the rarity of this condition and emphasized the diagnostic value of ultrasonography and magnetic resonance imaging (MRI) in differentiating canal of Nuck endometriosis from more common groin pathologies [\u003cspan additionalcitationids=\"CR9 CR10 CR11 CR12\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. A summary of previously reported cases, including the present case, is provided in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eIn the present case, the lesion was non-communicating (encysted) and showed no peritoneal communication, consistent with most reported canal of Nuck endometriomas. Non-communicating lesions can be managed with simple surgical excision, whereas communicating lesions may require high ligation of the processus vaginalis and hernia repair to prevent recurrence [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. This distinction is clinically relevant for surgical planning and intraoperative decision-making. Our case is notable for several uncommon features. First, the lesion was exceptionally large, measuring approximately 15 cm and causing significant vulvar displacement, which is rarely described in the literature. Second, the patient had no cyclic pain, an atypical presentation that can delay diagnosis. Although cyclic pain is considered suggestive of endometriosis, most reported canal of Nuck endometriosis cases present as painless groin masses, and the absence of cyclic symptoms does not exclude the diagnosis [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. These features highlight the diagnostic challenges and the importance of maintaining a high index of suspicion in women presenting with vulvar or inguinal masses. MRI played a crucial role in preoperative evaluation by identifying hemorrhagic components and delineating the relationship of the lesion to the round ligament and peritoneal cavity [\u003cspan additionalcitationids=\"CR9 CR10 CR11\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Nevertheless, histopathological examination remains the gold standard for definitive diagnosis. Complete surgical excision was curative in our patient, with no recurrence observed during three years of follow-up, consistent with previously reported outcomes showing low recurrence rates after complete resection [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOverall, this case underscores the importance of considering canal of Nuck endometriosis in the differential diagnosis of female groin or vulvar masses, even in the absence of cyclic pain. Early recognition, appropriate imaging, and complete surgical excision are essential for accurate diagnosis and optimal outcomes.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u0026bull; \u003cb\u003eMRI\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMagnetic resonance imaging\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u0026bull; \u003cb\u003eUS\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eUltrasonography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u0026bull; \u003cb\u003eIVF\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eIn vitro fertilization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval for this study was obtained from the Institutional Review Board of King Saud University Medical City. The study was conducted in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from the patient for participation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent for publication of this case report and any accompanying images was obtained from the patient.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo, I do not have any research data outside the submitted manuscript file.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo, I declare that the authors have no competing interests as defined by BMC, or other interests that might be perceived to influence the results and/or discussion reported in this paper.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research did not receive funding.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eL.A. was solely responsible for the conception and design of the case report, acquisition and interpretation of clinical data, drafting and critical revision of the manuscript, and approval of the final version for publication. The author agrees to be accountable for all aspects of the work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTilva H, Tayade S, Kanjiya A. Contemporary Review of Masses in the Canal of Nuck. Cureus. 2023;15(3):e36722. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.7759/cureus.36722\u003c/span\u003e\u003cspan address=\"10.7759/cureus.36722\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePatnam V, Narayanan R, Kudva A. A cautionary approach to adult female groin swelling: hydrocoele of the canal of Nuck with a review of the literature. BMJ Case Rep. 2016;2016:bcr2015212547. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1136/bcr-2015-212547\u003c/span\u003e\u003cspan address=\"10.1136/bcr-2015-212547\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLohourou GF, Kpangni AJB, Adoubs BC, Traor\u0026eacute; I, Bony UC, Traor\u0026eacute; AM, et al. Hydrocele of the Nuck canal. J Pediatr Surg Case Rep. 2023;89:102502. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.epsc.2022.102502\u003c/span\u003e\u003cspan address=\"10.1016/j.epsc.2022.102502\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang CJ, Chao AS, Wang TH, Wu CT, Chao A, Lai CH. Challenge in the management of endometriosis in the canal of Nuck. Fertil Steril. 2009;91(3):e9369\u0026ndash;93611. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.fertnstert.2008.07.1713\u003c/span\u003e\u003cspan address=\"10.1016/j.fertnstert.2008.07.1713\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eProdromidou A, Pandraklakis A, Rodolakis A, Thomakos N. Endometriosis of the Canal of Nuck: A Systematic Review of the Literature. Diagnostics (Basel). 2020;11(1):3. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/diagnostics11010003\u003c/span\u003e\u003cspan address=\"10.3390/diagnostics11010003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKohlhauser M, Pirsch JV, Maier T, Viertler C, Fegerl R. The Cyst of the Canal of Nuck: Anatomy, Diagnostic and Treatment of a Very Rare Diagnosis-A Case Report of an Adult Woman and Narrative Review of the Literature. Med (Kaunas). 2022;58(10):1353. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/medicina58101353\u003c/span\u003e\u003cspan address=\"10.3390/medicina58101353\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNasser H, King M, Rosenberg HK, Rosen A, Wilck E, Simpson WL. Anatomy and pathology of the canal of Nuck. Clin Imaging 2018 Sep-Oct;51:83\u0026ndash;92. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.clinimag.2018.02.003\u003c/span\u003e\u003cspan address=\"10.1016/j.clinimag.2018.02.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHwang B, Bultitude J, Diab J, Bean A. Cyst and endometriosis of the canal of Nuck: rare differentials for a female groin mass. J Surg Case Rep. 2022;2022(1):rjab626. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/jscr/rjab626\u003c/span\u003e\u003cspan address=\"10.1093/jscr/rjab626\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePapadoliopoulou M, Margaris I, Giannakis A, Samaras MG, Michalopoulos NV, Kokoropoulos P, Panayiotides I, Arkadopoulos N. Nuck Canal Endometriosis Following IVF Attempts in a Young Patient-Report of a Case. Clin Pract. 2024;14(4):1245\u0026ndash;50. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/clinpract14040100\u003c/span\u003e\u003cspan address=\"10.3390/clinpract14040100\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaram K, Azizi L, Azizi M, Dabaj E. Going Against the Grain: A Case Report of an Endometriosis in the Canal of Nuck. Eur J Case Rep Intern Med. 2024;11(12):005024. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.12890/2024_005024\u003c/span\u003e\u003cspan address=\"10.12890/2024_005024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNimodia D, Parihar P, Banode P, Dudhe SS, Desale P, Gaur S. Hidden Depths: Unveiling Endometriosis in the Canal of Nuck. Cureus. 2024;16(7):e64975. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.7759/cureus.64975\u003c/span\u003e\u003cspan address=\"10.7759/cureus.64975\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eProdromidou A, Paspala A, Schizas D, Spartalis E, Nastos C, Machairas N. Cyst of the Canal of Nuck in adult females: A case report and systematic review. Biomed Rep. 2020;12(6):333\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3892/br.2020.1295\u003c/span\u003e\u003cspan address=\"10.3892/br.2020.1295\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRchidi J, Kallel Y, Laamiri G, Alouani H, Bouassida M, Touinsi H. Canal of Nuck cyst in adulthood: A rare differential for inguinal masses - A case report. Int J Surg Case Rep. 2025;133:111568. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ijscr.2025.111568\u003c/span\u003e\u003cspan address=\"10.1016/j.ijscr.2025.111568\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMedić F, Pavlović M, Bekavac Vlatković I, Rašić F, Jug-Klobučić A. Endometriosis of the canal of Nuck: diagnosis and treatment. Arch Gynecol Obstet. 2024;310(4):2265\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00404-024-07711-y\u003c/span\u003e\u003cspan address=\"10.1007/s00404-024-07711-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-womens-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmwh","sideBox":"Learn more about [BMC Women's Health](http://bmcwomenshealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmwh/default.aspx","title":"BMC Women's Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Canal of Nuck, endometriosis, endometrioma, vulvar swelling, hydrocele, case report","lastPublishedDoi":"10.21203/rs.3.rs-9075998/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9075998/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003eEndometriosis of the canal of Nuck is an extremely rare manifestation of extrapelvic endometriosis that may mimic common groin pathologies such as inguinal hernia or hydrocele, often leading to diagnostic difficulty and delayed recognition.\u003c/p\u003e\u003ch2\u003eCase Presentation:\u003c/h2\u003e \u003cp\u003eWe report the case of a 29-year-old nulliparous woman who presented with a gradually enlarging painless swelling in the right vulvar region over eight months. Physical examination revealed a large cystic mass measuring approximately 15 \u0026times; 10 cm involving the right vulva and inguinal area with displacement of the clitoris and vaginal introitus. Ultrasonography demonstrated a well-defined cystic lesion with internal echoes, while magnetic resonance imaging revealed a hemorrhagic cystic lesion along the course of the canal of Nuck without peritoneal communication. Surgical exploration identified a cystic mass adjacent to the round ligament containing characteristic \u0026ldquo;chocolate-like\u0026rdquo; fluid. Complete excision of the lesion was performed. Histopathological examination confirmed endometrioma of the canal of Nuck. The postoperative course was uneventful, and the patient remained asymptomatic with no evidence of recurrence during three years of follow-up.\u003c/p\u003e\u003ch2\u003eConclusion:\u003c/h2\u003e \u003cp\u003eAlthough rare, canal of Nuck endometriosis should be considered in the differential diagnosis of inguinal or vulvar masses in women of reproductive age. Early recognition with appropriate imaging and complete surgical excision allows accurate diagnosis and excellent outcomes. To our knowledge, this case represents one of the largest canal of Nuck endometriomas reported in the literature and highlights the diagnostic challenges posed by atypical presentations without cyclic symptoms.\u003c/p\u003e","manuscriptTitle":"Giant Endometrioma of the Canal of Nuck Mimicking a Vulvar Mass: A Rare Case and Narrative Review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-03 06:20:50","doi":"10.21203/rs.3.rs-9075998/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-03T10:27:40+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"331794782405015133479944709899963678129","date":"2026-04-03T08:32:50+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-01T17:02:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-01T15:13:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-01T11:28:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"71196991236171947235281221558854015553","date":"2026-04-01T09:30:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"115105396537189472878805300076540476778","date":"2026-03-31T15:56:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"80782830647046458786761624278885099410","date":"2026-03-31T11:27:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"340010146927282934335030051138394305187","date":"2026-03-30T13:17:05+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-30T09:56:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"54237066923071729111566760523039211093","date":"2026-03-30T09:17:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-30T01:37:52+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"83673714188312039195500831081528619998","date":"2026-03-30T01:24:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"95550991394957873920992753530638335526","date":"2026-03-29T13:36:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-29T11:31:46+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-29T10:58:03+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-16T13:51:17+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-13T14:13:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Women's Health","date":"2026-03-12T20:38:24+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-womens-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmwh","sideBox":"Learn more about [BMC Women's Health](http://bmcwomenshealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmwh/default.aspx","title":"BMC Women's Health","twitterHandle":"","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ef090623-5168-40d5-aa57-08c344c65985","owner":[],"postedDate":"April 3rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-24T07:57:03+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-03 06:20:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9075998","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9075998","identity":"rs-9075998","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}