{"paper_id":"45dfb145-1f39-4275-8c3e-f0514cb72486","body_text":"Review began\n 09/21/2026 \nReview ended\n 10/04/2026 \nPublished\n 10/09/2026\n© Copyright \n2026\nKhan. This is an open access article\ndistributed under the terms of the Creative\nCommons Attribution License CC-BY 4.0.,\nwhich permits unrestricted use, distribution,\nand reproduction in any medium, provided\nthe original author and source are credited.\nDOI:\n 10.7759/cureus.117693\nAppendiceal Endosalpingiosis: A Rare Cause of\nAppendicitis-Like Presentation\nHamza Khan \n1.\n General and Colorectal Surgery, Royal Perth Bentley Group, Perth, AUS\nCorresponding author: \nHamza Khan, \nhamzafnk1@gmail.com\nAbstract\nWe report a case of a 55-year-old female who presented to the emergency department with symptoms of\nappendicitis. Imaging demonstrated appendiceal mucocele and possible early appendicitis. She underwent a\nlaparoscopic appendectomy and subsequent histopathology demonstrated irregular fibrosis of the\nappendiceal wall as a result of endosalpingiosis with secondary mucocele formation.\nIn this report, we present an exceedingly rare case of endosalpingiosis causing an appendicitis mimic.\nAlthough endosalpingiosis is typically considered a benign incidental finding, appendiceal involvement can\nmimic acute appendicitis, as in this case, and may be associated with an increased risk of gynecologic\nmalignancy. The patient was followed up with the gynecological team due to this malignancy risk and is\nplanned for laparoscopic oophorectomy, with the final histopathology diagnosis being appendiceal\nendosalpingiosis with secondary mucocele.\nCategories:\n General Surgery\nKeywords:\n atypical appendicitis, diagnosis of acute appendicitis, emergency general surgery, endosalpingiosis,\ngeneral surgery\nIntroduction\nAppendicitis is inflammation of the vestigial appendix and is one of the most common causes of emergency\nabdominal surgery \n[1]\n. The appendix is located at the base of the cecum, near the ileocecal valve, where the\ntaenia coli converge on the cecum \n[2]\n. The Global Burden of Disease reported 17 million incident cases of\nappendicitis in 2021, and it occurs most frequently in people in their 20s and 30s \n[3]\n. The classical\npathogenesis of appendicitis is usually stated to be due to direct luminal obstruction. This can be caused by\nfecalith, lymphoid hyperplasia due to infection in young patients, fibrosis, or neoplasia. The classical history\nof appendicitis involves generalized abdominal pain that migrates to the right lower quadrant (RLQ),\nalthough this is only seen in 50-60% of patients with appendicitis. In summary, appendicitis is a very\ncommon surgical pathology with varying causes \n[4]\n. In this case, we describe fibrosis of the appendiceal wall\nas a result of endosalpingiosis in a 55-year-old female. This is a very rare cause of acute appendicitis.\nCase Presentation\nThis case involves a 55-year-old female with a background history of endometriosis and hypertension\n(HTN). Her surgical history includes hiatal hernia and diaphragmatic hernia repair, C3-C4 and C4-C5 spinal\nfusion, and one C-section. The patient is postmenopausal but has a history of a single instance of\npostmenopausal bleeding. She is otherwise well and healthy, independent, lives at home with family, and\ndoes not smoke or drink alcohol.\nShe presented to our emergency department with a five-day history of right iliac fossa (RIF) pain that\ngradually increased in intensity. On the day of admission, the pain increased in intensity drastically, which\nprompted her to present to the emergency department. She described the pain as “grabbing” with no\nradiation. She reported that the pain was worse with movement and deep inspiration and did not have any\nurinary, bowel, or vaginal symptoms. She had no urinary, bowel, or vaginal symptoms and reported no\nnausea or vomiting. She was systemically well and afebrile on presentation.\nOn presentation, she was hemodynamically stable with no recorded fever; however, she was visibly\nuncomfortable with small movements. She was warm, well perfused, and euvolemic with normal heart and\nlung sounds. Her abdomen was soft, with tenderness in the RIF and right upper quadrant (RUQ), guarding,\nand a positive Rovsing’s sign. Given the findings on abdominal examination and clinical suspicion for acute\nappendicitis, she underwent a CT abdomen and pelvis.\nInvestigations\nHer blood tests demonstrated a white cell count (WCC) of 7.06×10\n9\n/L (4.00-1.00×10\n9\n/L) and neutrophil\ncount of 4.60×10\n9\n/L (2.00-7.50×10\n9\n/L). Her CRP was 8.4 mg/L (<5.0 mg/L) and lactate was 0.9 mmol/L (<2.0\n1\n \nOpen Access Case Report\nHow to cite this article\nKhan H (October 09, 2026) Appendiceal Endosalpingiosis: A Rare Cause of Appendicitis-Like Presentation. Cureus 18(10): e117693. \nDOI\n10.7759/cureus.117693\n\nmmol/L). The rest of her routine biomarkers were within normal ranges. She had surprisingly low\ninflammatory markers for a patient with possible appendicitis and five days of symptoms. Her CT abdomen\nand pelvis demonstrated a blind-ending tubular structure that communicates with the focal ovoid dilation at\nthe tip, measuring up to 11 mm with internal low-attenuation (22 Hounsfield units {HU}) content,\nsuggesting appendiceal mucocele without features of rupture (Figures \n1\n, \n2\n). There was no calcification or\nappendicolith, no significant peri-appendiceal fat stranding, free gas, or drainable collection.\nFIGURE\n 1: CT scan showing a blind-ending tubular structure\ncommunicating with focal ovoid dilation at tip (red arrow).\n \n2026 Khan et al. Cureus 18(10): e117693. DOI 10.7759/cureus.117693\n2\n of \n6\n\nFIGURE\n 2: Focal ovoid dilation seen on CT at the time of presentation\n(red arrow).\nTreatment\nThe patient was commenced on intravenous amoxicillin-clavulanate potassium, 2.2 g three times daily as\nper local hospital protocol, and underwent a laparoscopic appendectomy on the same day as her\npresentation. Intraoperative findings showed a mildly inflamed, non-perforated appendix with surrounding\ninflammatory tissue. There was no free fluid in the pelvis, and the base of the appendix was healthy with no\nspreading inflammation to the cecum. Care was taken not to spill any mucocele during the procedure. Extra\nprecautions were taken, such as not letting the dissected appendix touch any body surface and applying\ndiathermy to the appendiceal stump to ensure an adequate seal was formed.\nFollow-up\nThe patient received her histopathology results during a telephone consultation three weeks after surgery.\nFollowing her operation, the patient was well and returned to daily life with the restrictions of not lifting\nmore than 5 kg for six weeks. She returned to the ED with abdominal pain but was discharged with safety\nnetting after a normal repeat CT scan and blood tests. She had no postoperative complications. Her\nhistopathology results are detailed below.\nMacroscopic\nThe appendix measured 38 mm in length and 15 mm in diameter. The attached mesoappendix measured 14\nmm. The serosal surface was gray-tan in color, with a glossy appearance. The lumen contained a\ntransparent, gelatinous-like material. The wall thickness measured up to 4 mm.\nMicroscopic\nThere was irregular fibrosis of the appendiceal wall as a result of endosalpingiosis. There was secondary\nmucocele formation. There were no features of malignancy. No active inflammation was noted. The mucosa\nat the resection margin was unremarkable and consistent with normal large bowel mucosa.\nAlthough the histopathology did not show active inflammation, the case was described as acute appendicitis\ngiven the clinical presentation, which was consistent with the classical presentation of appendicitis. She was\nfollowed up in the gynecological clinic given the histopathology findings and was booked for a laparoscopic\noophorectomy.\nDiscussion\nAppendiceal mucinous lesions are a relatively rare finding characterized by a distended, mucus-filled, or\n \n2026 Khan et al. Cureus 18(10): e117693. DOI 10.7759/cureus.117693\n3\n of \n6\n\nruptured appendix. There are an estimated 3500 cases of appendiceal mucinous neoplasms diagnosed\nannually in the United States \n[5]\n. Appendiceal mucinous lesions have a slight predominance in females and\nare usually diagnosed in patients in their 50s and 60s \n[6]\n.\nThe development of appendiceal mucocele is usually due to obstruction and increased accumulation of\nmucus within the appendix lumen. The etiology can range from a simple retention cyst to a malignant\nneoplasm. Diagnosis of a mucocele should be made promptly, as a ruptured neoplastic mucocele can lead to\ndevelopment of pseudomyxoma peritonei, colloquially known as “jelly belly.” This can result in\ndisseminated mucin-producing cells throughout the peritoneal cavity, which can drastically worsen patient\nprognosis and outcomes \n[7]\n.\nAppendiceal mucinous lesions can be classified broadly into two categories. Non-neoplastic lesions involve\nsimple mucoceles or retention cysts. These are characterized by degenerative epithelial changes due to\nobstruction and distension, such as in the case of a fecalith, without evidence of mucosal hyperplasia or\nneoplasia. Neoplastic appendiceal mucinous lesions can be subdivided into serrated polyps, mucinous\nappendiceal neoplasms, and mucinous adenocarcinoma of the appendix \n[8]\n.\nEndosalpingiosis is the presence of epithelium that resembles the fallopian tube endothelium in a non-\nnative area, including pelvic organs, ovaries, pelvic peritoneum, bladder, or fallopian tube serosa \n[9,10]\n. It is\nnot well studied, and definitive diagnosis is only made after surgical biopsy \n[11]\n. It is often an incidental\nfinding during pelvic surgery.\nThere have been studies that describe the association between endosalpingiosis and ovarian cancer. A study\nof 110 cases of endosalpingiosis found endometrial adenocarcinoma in 16% of cases and borderline ovarian\ntumors in 7% of cases. In the patients with borderline ovarian tumors, endosalpingiosis was found on the\novary (37%), fallopian tube (21%), omentum (9%), and uterine serosa (7%) \n[12]\n. Another study of 838 cases\nreported that patients with endosalpingiosis were more likely to have serous borderline, invasive mucinous,\nand clear cell ovarian tumors when compared to a population control group \n[13]\n. A large retrospective study\nof 2490 patients with a histological diagnosis of endosalpingiosis had a higher incidence of ovarian cancer\nthan the control group \n[14]\n. While endosalpingiosis is not well studied, these few studies establish a\npotential link between endosalpingiosis and increased malignancy risk, indicating that it is a condition of\nconsequence and not merely an incidental finding. Although a definite causal relationship has not been\nestablished, an association between endosalpingiosis and malignancy has been reported.\nEndosalpingiosis of the appendix is significantly rarer. Esselen et al. described only 20 cases of appendiceal\nendosalpingiosis from 1998 to 2013 \n[13]\n. Of these cases, Tudor et al. described two cases of women in their\n40s-50s presenting with classical appendicitis symptoms \n[15]\n. Both of these cases had normal inflammatory\nmarkers, with histopathology confirming the diagnosis of endosalpingiosis. Cajigas and Axiotis described a\nsimilar case to ours but with mild leukocytosis and a normal-appearing appendix intraoperatively \n[16]\n.\nOther reports describe similar presentations, indicating that these patients often present with presumed\nmild appendicitis and the diagnosis is only confirmed after histopathology.\nThere is very limited research regarding appendicitis secondary to endosalpingiosis. However, there is an\nassociation with increased malignancy risk, especially ovarian cancer. Esselen et al. also described an\nincreased risk of ovarian invasive mucinous cancer in patients with endosalpingiosis \n[13]\n. Given the current\nliterature, cases such as these should be closely followed up by the gynecological team for further\nmalignancy workup. Surgeons should take care to chase the histopathology in patients who have presumed\nmucinous appendicitis and refer to the appropriate team to avoid missing a potential gynecologic\nmalignancy.\nLimitations\nThe main limitation of this case is the lack of literature on endosalpingiosis causing an appendicitis mimic.\nAs mentioned, only 20 cases have been described in the literature. Furthermore, an association between\nendosalpingiosis and gynecological malignancy has been demonstrated, but a true causation cannot be\nproven. Lastly, this patient is undergoing evaluation by the gynecological team; therefore, long-term follow-\nup was not available at the time of publication.\nConclusions\nEndosalpingiosis can be a rare cause of appendicitis mimic and can often present with classical appendicitis\nsymptoms but with minimal inflammatory response on blood tests, imaging, or histopathology.\nEndosalpingiosis was previously thought to be a benign incidental finding, but recent studies have\ndemonstrated an association with increased malignancy risk. If found intraoperatively or on histopathology\npostoperatively, the surgical team should refer to the gynecological team for further workup and\nmanagement of potential malignancy. The main finding of this case is that endosalpingiosis has been\nassociated with increased gynecological malignancy risk and can mimic appendicitis and cause mucocele\nformation.\n \n2026 Khan et al. Cureus 18(10): e117693. DOI 10.7759/cureus.117693\n4\n of \n6\n\nAppendices\nPatient experience\nI have a history of endometriosis and have always had very painful menstrual cycles and right-sided pelvic\npain. I had postmenopausal bleeding, and thickened endometrium of 9 mm and a hypoechoic lesion within\nthe endometrium measuring 9x7 mm with an echogenic rim. I was referred to a gynecologist, who did a\nhysteroscopy and endometrial biopsy. The report came back unremarkable; the endometrium was atrophic,\nno curettings were obtained, and there was no evidence of fibroids or polyps.\nI am always bloated and have a dull, aching pain most of the time in the right pelvic area. Leading up to the\nappendix removal, I was doing housework and experienced right-sided pain so bad I couldn't walk, and my\nson had to help me to lie down. I thought I must have twisted the wrong way or had pulled something. So I\nput a wheat bag on it. Pain was at least a 10, a grabbing-like pain, and intense, and if I lay down and did not\nmove, it was okay. I tried to put a pillow under my legs; again, pain was at a 10. I rested that afternoon; the\nnext morning, pain was at a 10 when I would sit down, get up, or walk. Driving was ok but again, when I tried\nto get out and stand, the pain was back. Over the next few days, the pain was intermittent but immediately\n10 when I went from sitting to standing. One night, the pain woke me up; I couldn't get up or walk, and then\nI went to the hospital.\nI am still experiencing bloating, bleeding, and right-sided pelvic pain, so I made an appointment with my\nGP, who advised me to go back to the ED for follow-up, which I did. I was then referred to the gynecological\nteam. I had an appointment with a gynecologist who suggested I have a laparoscopic oophorectomy.\nHowever, I went back to my specialist, who thinks that, given my history, it would be better to have a full\nhysterectomy including fallopian tubes and ovaries. I am still deciding the best option, but after reading your\nresearch, I will probably get the full hysterectomy, including the fallopian tubes and ovaries, due to the risk\nof malignancy from the appendix findings.\nAdditional Information\nAuthor Contributions\nAll authors have reviewed the final version to be published and agreed to be accountable for all aspects of the\nwork.\nConcept and design:\n  \nHamza Khan\nAcquisition, analysis, or interpretation of data:\n  \nHamza Khan\nDrafting of the manuscript:\n  \nHamza Khan\nCritical review of the manuscript for important intellectual content:\n  \nHamza Khan\nDisclosures\nHuman subjects:\n Informed consent for treatment and open access publication was obtained or waived by all\nparticipants in this study. \nConflicts of interest:\n In compliance with the ICMJE uniform disclosure form, all\nauthors declare the following: \nPayment/services info:\n All authors have declared that no financial support\nwas received from any organization for the submitted work. \nFinancial relationships:\n All authors have\ndeclared that they have no financial relationships at present or within the previous three years with any\norganizations that might have an interest in the submitted work. \nOther relationships:\n All authors have\ndeclared that there are no other relationships or activities that could appear to have influenced the\nsubmitted work.\nReferences\n1\n. \nWilliams GR: \nPresidential address: a history of appendicitis. 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Ann Surg Oncol. 2018, 25:2135-44.\n10.1245/s10434-018-6488-4\n6\n. \nAho AJ, Heinonen R, Laurén P: \nBenign and malignant mucocele of the appendix. Histological types and\nprognosis\n. Acta Chir Scand. 1973, 139:392-400.\n7\n. \nGopalan V, Khan IA, Zade AA, Malhotra G, Durge S, Jain Y, Rekavari SG: \nDiagnostic challenges and\n \n2026 Khan et al. Cureus 18(10): e117693. DOI 10.7759/cureus.117693\n5\n of \n6\n\ntreatment options for mucocele of the appendix: a comprehensive review [sic].\n. Cureus. 2024,\n16:\n10.7759/cureus.66142\n8\n. \nCarr NJ, Cecil TD, Mohamed F, et al.: \nA consensus for classification and pathologic reporting of\npseudomyxoma peritonei and associated appendiceal neoplasia: the results of the Peritoneal Surface\nOncology Group International (PSOGI) modified Delphi process\n. Am J Surg Pathol. 2016, 40:14-26.\n10.1097/PAS.0000000000000535\n9\n. \nBatt RE, Yeh J: \nMüllerianosis: four developmental (embryonic) mullerian diseases\n. Reprod Sci. 2013,\n20:1030-7. \n10.1177/1933719112472736\n10\n. \nRajarubendra N, Leang Y, Monsour M: \nMullerianosis of the urinary bladder\n. ANZ J Surg. 2015, 85:292-3.\n10.1111/ans.12430\n11\n. \nLaufer MR, Heerema AE, Parsons KE, Barbieri RL: \nEndosalpingiosis: clinical presentation and follow-up\n.\nGynecol Obstet Invest. 1998, 46:195-8. \n10.1159/000010032\n12\n. \nPrentice L, Stewart A, Mohiuddin S, Johnson NP: \nWhat is endosalpingiosis?\n. Fertil Steril. 2012, 98:942-7.\n10.1016/j.fertnstert.2012.06.039\n13\n. \nEsselen KM, Terry KL, Samuel A, et al.: \nEndosalpingiosis: more than just an incidental finding at the time of\ngynecologic surgery?\n. Gynecol Oncol. 2016, 142:255-60. \n10.1016/j.ygyno.2016.05.036\n14\n. \nHermens M, van Altena AM, Bulten J, Siebers AG, Bekkers RL: \nIncreased association of ovarian cancer in\nwomen with histological proven endosalpingiosis\n. Cancer Epidemiol. 2020, 65:\n10.1016/j.canep.2020.101700\n15\n. \nTudor J, Williams TR, Myers DT, Umar B: \nAppendiceal endosalpingiosis: clinical presentation and imaging\nappearance of a rare condition of the appendix\n. Abdom Radiol. 2019, 44:3246-51. \n10.1007/s00261-018-\n1813-8\n16\n. \nCajigas A, Axiotis CA: \nEndosalpingiosis of the vermiform appendix\n. Int J Gynecol Pathol. 1990, 9:291-5.\n10.1097/00004347-199007000-00009\n \n2026 Khan et al. Cureus 18(10): e117693. DOI 10.7759/cureus.117693\n6\n of \n6","source_license":"CC0","license_restricted":false}