{"paper_id":"26eb7d44-b494-4990-bfaa-91dc7e1314b1","body_text":"Video Article\nJ Turk Ger Gynecol Assoc \nCopyright© 2026 The Author(s). Published by Galenos Publishing House on behalf of Turkish-German Gynecological Association. \nThis is an open access article under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 (CC BY-NC-ND) International License.\nIntroduction\nDysmenorrhea affects nearly 80% of adolescents, with severe \ncases that may indicate rare Müllerian duct anomalies, such \nas “accessory cavitated uterine mass (ACUM)” (1). ACUM is \ncharacterized by progressive worsening of dysmenorrhea, \npotentially related to gubernaculum dysfunction, and the \npresence of a non-communicating, accessory uterine cavity, \nwithout other uterine anomalies (2-4). Differential diagnoses \ninclude juvenile cystic adenomyosis, rudimentary cavitated \nuterine horns, and degenerated leiomyomas. Diagnostic \ncriteria for ACUM include an isolated accessory cavitated mass; \na normal uterus, fallopian tubes, and ovaries; excised mass \nwith confirmatory histopathological examination; an accessory \ncavity lined by endometrial epithelium with glands and stroma; \nchocolate-brown fluid content; and no adenomyosis except \nfor small foci of myometrium adjacent to the mass. ACUMs are \ntypically located on the anterior uterine wall (3). \nACUM is an uncommon pathological condition, primarily \nobserved in young individuals, characterized by severe \ndysmenorrhea and recurrent pelvic pain (5). The \naccompanying pain often localizes to the side of the mass \nand does not respond well to non-steroidal anti-inflammatory \ndrugs (NSAIDs) or combined oral contraceptives (COC) (3). \nThe primary treatment for ACUM is surgical excision, which \nprovides permanent relief and recovery. We present a 17-year-\nold adolescent girl diagnosed with ACUM, detailing her \ndiagnostic process, surgical management, and follow-up visits. \nAddress for Correspondence: Mehmet Tunç\ne-mail: mhmttunc@gmail.com ORCID: orcid.org/0000-0002-8646-0619\nDOI: 10.4274/jtgga.galenos.2025.2025-10-5\nCite this article as: Tunç M, Önalan G, Coşkun M, Haberal AN, Kuşçu ÜE. Accessory cavitated uterine mass: A rare cause of severe dysmenorrhea with \nliterature review. J Turk Ger Gynecol Assoc.  \nReceived: October 13, 2025 Accepted: December 15, 2025 Epub: January 22, 2026 \nAbstract\nWe present a rare Müllerian anomaly known as “accessory cavitated uterine mass (ACUM),” which causes severe, refractory dysmenorrhea, and \nreview the literature. A 17-year-old patient experienced severe, cyclic left-sided pelvic pain, correlating with menstruation. Magnetic resonance \nimaging (MRI) revealed a cystic lesion surrounded by myometrial tissue. Medical treatment with oral contraceptives was unsuccessful. \nLaparoscopic excision of the mass was performed, and histopathology confirmed the diagnosis of ACUM. At six months postoperatively, she \nremained asymptomatic, and follow-up MRI showed a normal-appearing uterus. ACUM is a rare Müllerian anomaly that is challenging to diagnose \npreoperatively, even with advanced imaging. Surgical excision remains the definitive treatment. This case highlights the importance of clinicians \nconsidering Müllerian anomalies in adolescents presenting with severe dysmenorrhea. [J Turk Ger Gynecol Assoc.  ]\nKeywords: Accessory cavitated uterine mass, ACUM, severe dysmenorrhea, Müllerian anomaly, juvenile cystic adenomyosis\n1Department of Obstetrics and Gynecology, Başkent University Faculty of Medicine, Ankara, Türkiye\n2Department of Radiology, Başkent University Faculty of Medicine, Ankara, Türkiye\n3Department of Pathology, Başkent University Faculty of Medicine, Ankara, Türkiye\n Mehmet Tunç1,  Göğşen Önalan1,  Mehmet Coşkun2,  Asuman Nihan Haberal3,  Ülkü Esra Kuşçu1 \nAccessory cavitated uterine mass: A rare cause of \nsevere dysmenorrhea\n\nTunç et al.\nACUM: A rare cause of severe dysmenorrhea and review of the literature\n \nCase report\nA left-sided 27x10 mm mass with a hemorrhagic component \non the anterior corpus of the uterus, suggesting a non-\ncommunicating uterine horn, was detected by pelvic ultrasound \nin a 17-year-old patient with severe cyclic dysmenorrhea. Pelvic \nmagnetic resonance imaging (MRI) revealed a hemorrhagic \nsegment within the mass, surrounded by myometrial tissue \n(Figure 1). Laparoscopic mass excision with diagnostic \nhysteroscopy was scheduled to assess for any ostia from the \ncavitated mass into the endometrial cavity, after refractory pain \nduring medical treatment with COC.\nBoth tubal ostia were patent during hysteroscopy, which \nrevealed a regular endometrial cavity without signs of any \naccessory cavity or ostia. \nSubsequently, laparoscopic resection of the mass was \nperformed (Figures 2-5). A brief video of the operation is \navailable in Video 1. The following steps were performed \nduring surgery. Firstly, the opening of the anterior surface of the \nuterine peritoneum. After that, a uterine mass was observed \non the left side of the uterus. The incision was extended along \nthe left round ligament. Unipolar cautery was used for the \nexcision of the mass. During cauterization, chocolate-brown \ncolored endometriotic fluid was released from the cavitated \nuterine mass. The fluid was aspirated from the cavitated mass. \nFollowing that step, the ACUM was enucleated from the uterus. \nAfter the excision of the mass, the resulting uterine defect was \nrepaired with V-Loc™ suture.\nThe procedure was well tolerated with no postoperative \ncomplications. She was discharged the next day. Histopathology \nconfirmed the endometrial glands and stroma within the \ncavity tissue, with small foci of adenomyosis in the adjacent \nmyometrium. At six months postoperatively, she reported \nresolution of dysmenorrhea with regular menstrual cycles, and \nFigure 1. T2-weighted magnetic resonance imaging image \nof the mass (accessory cavitated uterine mass)\nFigure 2. Opening of the anterior surface of the uterine \nperitoneum\nFigure 3. Endometrial lumen of the accessory cavitated \nuterine mass\nFigure 4. Suturing of the myometrial defect\n\n\nTunç et al.\nACUM: A rare cause of severe dysmenorrhea and review of the literature\n  \nfollow-up MRI showed a normal appearing uterus (Figure 6).\nWritten informed consent was obtained from the patient and \nher parents for both the surgical procedure and the publication \nof this case report, with approval of the Başkent University Non-\nInterventional Clinical Research Ethics Committee (approval \nnumber: 22/226, date: 28.12.2022).board.\nDiscussion\nThis case report illustrates ACUM, highlighting its symptoms, \ndiagnostic evaluation (pelvic ultrasound and MRI), medical \nmanagement, surgical excision, and follow-up. The initial \nphysical examination revealed a mass on ultrasound and \npelvic MRI consistent with ACUM. Medical treatment provided \nminimal relief, leading to laparoscopic resection. The patient’s \nsymptoms completely resolved following the excision. \nACUM is a rare Müllerian anomaly and is often difficult to \ndiagnose preoperatively due to its infrequent occurrence and \nsimilarities to other pelvic conditions. In adolescents, severe \ncyclic dysmenorrhea, refractory to NSAIDs or COCs, should raise \nsuspicion for Müllerian anomalies. The differential diagnosis \nshould include pedunculated myomas, endometriomas, and \npara-ovarian cysts (6). Literature describes similar lesions under \nvarious names, including juvenile cystic adenomyoma, cystic \nadenomyoma, cystic adenomyosis, and accessory cavitated \nmass. The term ACUM is now preferred and has replaced the \nterm “juvenile cystic adenomyoma” due to reflecting the nature \nof the condition more accurately, as described by Takeda et al. \n(7). Recently, Sachedina Parhar et al. (8) proposed the term \n“accessory uterine cavities” for this entity. Precise diagnosis \ndepends on intraoperative and histopathological findings.\nOur case meets the established diagnostic criteria for ACUM (3). \nWhile MRI can suggest the diagnosis, definitive confirmation \nrequires surgical excision and histopathological examination \n(9). Video footage from the presented patient’s surgery \nillustrates the drainage of chocolate-brown fluid, indicative of \nold blood, as previously reported (6). Histopathological analysis \nnoted small foci of adenomyosis in the myometrium adjacent \nto the mass. Notably, our case differed from most reported \ncases of ACUM, which typically present on the right side of the \nuterus (10).\nConclusion \nACUM remains a rare form of Müllerian anomaly and is \ndifficult to diagnose preoperatively despite advanced imaging \ntechniques. Surgical excision performed through laparotomy \nor laparoscopy remains the definitive treatment. Laparoscopic \nprocedures are associated with a lower complication rate \nand higher operative satisfaction (11). This aim of this report \nwas to highlight this rare condition and so remind clinicians \nto consider Müllerian anomalies in this patient demographic. \nThis report highlights the need to consider ACUM in the \ndifferential diagnosis of severe dysmenorrhea. It underscores \nthe importance of including ACUM in the differential diagnosis \nand highlights the effectiveness of surgical excision for long \nterm relief. Moreover, we offer a step-by-step video for ACUM \nexcision. The complete resolution of our patient’s symptoms \nwithout complications highlights the effectiveness and safety \nof the surgical approach.  \nVideo 1.\nhttp://dx.doi.org/10.4274/jtgga.galenos.2025.2025-10-5.video1\nEthics\nEthics Committee Approval: This study was approved by the \nBaşkent University Non-Interventional Clinical Research Ethics \nCommittee (approval number: 22/226, date: 28.12.2022).\nFigure 6. Magnetic resonance imaging image of the uterus \nafter surgery\nFigure 5. Final appearance of the uterus\n\n\nTunç et al.\nACUM: A rare cause of severe dysmenorrhea and review of the literature\n \nInformed Consent: Written informed consent was obtained \nfrom the patient and her parents for both the surgical procedure \nand the publication.\nFootnotes\nConflict of Interest: No conflict of interest is declared by the \nauthors.\nFinancial Disclosure: The authors declared that this study \nreceived no financial support.\nReferences\n1. Agarwal AK, Agarwal A. A study of dysmenorrhea during \nmenstruation in adolescent girls. Indian J Community Med. 2010; \n35: 159-64.\n2. Deng F, Liu K, Huang Y, Chen Q, Wang L, Xiao X, et al. Successful \ntreatment of a rare giant accessory cavitated uterine mass: a case \nreport. J Int Med Res. 2024; 52: 3000605241252238.\n3. Acién P , Bataller A, Fernández F, Acién MI, Rodríguez JM, Mayol MJ. \nNew cases of accessory and cavitated uterine masses (ACUM): a \nsignificant cause of severe dysmenorrhea and recurrent pelvic pain \nin young women. Hum Reprod. 2012; 27: 683-94.\n4. Grimbizis GF, Di Spiezio Sardo A, Saravelos SH, Gordts S, Exacoustos \nC, Van Schoubroeck D, et al. The Thessaloniki ESHRE/ESGE \nconsensus on diagnosis of female genital anomalies. Gynecol Surg. \n2016; 13: 1-16.\n5. Garofalo A, Alemanno MG, Sochirca O, Pilloni E, Garofalo G, \nChiadò Fiorio Tin M, et al. Accessory and cavitated uterine mass \nin an adolescent with severe dysmenorrhoea: from the ultrasound \ndiagnosis to surgical treatment. J Obstet Gynaecol. 2017; 37: 259-61.\n6. Paul PG, Chopade G, Das T, Dhivya N, Patil S, Thomas M. Accessory \ncavitated uterine mass: a rare cause of severe dysmenorrhea in \nyoung women. J Minim Invasive Gynecol. 2015; 22: 1300-3.\n7. Takeda A, Sakai K, Mitsui T, Nakamura H. Laparoscopic \nmanagement of juvenile cystic adenomyoma of the uterus: report \nof two cases and review of the literature. J Minim Invasive Gynecol. \n2007; 14: 370-4.\n8. Sachedina Parhar A, Mellor A, Moeed S, Grover SR. Accessory \nuterine cavities: a review of cases and an appeal for standard \nterminology. Fertil Steril. 2025; 123: 1101-13.\n9. Bedaiwy MA, Henry DN, Elguero S, Pickett S, Greenfield M. \nAccessory and cavitated uterine mass with functional endometrium \nin an adolescent: diagnosis and laparoscopic excision technique. J \nPediatr Adolesc Gynecol. 2013; 26: e89-91.\n10. Acién P , Acién M, Fernández F, José Mayol M, Aranda I. The cavitated \naccessory uterine mass: a Müllerian anomaly in women with an \notherwise normal uterus. Obstet Gynecol. 2010; 116: 1101-9.\n11. Otten LA, Lama S, Otten JW , Winkler K, Ralser DJ, Egger EK, et al. \nClinical comparison of laparoscopic and open surgical approaches \nfor uterus-preserving myomectomy: a retrospective analysis on \npatient-reported outcome, postoperative morbidity and pregnancy \noutcomes. Arch Gynecol Obstet. 2025; 311: 1359-69.","source_license":"public-domain-us","license_restricted":false}