{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T16:07:23Z","timestamp":1772726843495,"version":"3.50.1"},"reference-count":10,"publisher":"SMC Media","issue":"3","license":[{"start":{"date-parts":[[2026,2,23]],"date-time":"2026-02-23T00:00:00Z","timestamp":1771804800000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>Ovarian collision tumours are rare entities defined by the coexistence of two histologically distinct neoplasms, most commonly reported within the same ovary, while bilateral involvement is extremely uncommon and often under-recognised. Endometriomas are common benign ovarian lesions in women of reproductive age and may be asymptomatic or incidentally detected, whereas mature cystic teratomas are the most frequent ovarian germ cell tumours and are often discovered unintentionally during imaging or surgery. We report the case of a 27-year-old woman in whom adnexal lesions were incidentally identified, with no significant gynaecologic symptoms at presentation. Pelvic magnetic resonance imaging (MRI) showed bilateral ovarian masses, and surgical exploration revealed distinct ovarian lesions involving both ovaries. Histopathological examination confirmed a mature cystic teratoma in one ovary and an endometrioma in the contralateral ovary. This unusual and incidental bilateral presentation highlights the limitations of preoperative imaging in detecting synchronous ovarian pathologies and underscores the importance of thorough intraoperative assessment and definitive histopathological evaluation. Increased awareness of this rare entity is essential to optimise surgical management, fertility preservation and follow-up.<\/jats:p>","DOI":"10.12890\/2026_006209","type":"journal-article","created":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T16:25:24Z","timestamp":1772209524000},"source":"Crossref","is-referenced-by-count":0,"title":["When two benign ovarian pathologies collide: an incidental bilateral collision tumour of mature cystic teratoma and endometrioma"],"prefix":"10.12890","volume":"13","author":[{"given":"Katherine","family":"Atallah","sequence":"first","affiliation":[{"name":"Department of Internal Medicine, University of Balamand, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Antonio","family":"Al Hazzouri","sequence":"first","affiliation":[{"name":"Department of Internal Medicine, University of Balamand, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kaity","family":"Saliba","sequence":"first","affiliation":[{"name":"Department of Internal Medicine, University of Balamand, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Philippe","family":"Attieh","sequence":"first","affiliation":[{"name":"Department of General Surgery, University of Balamand, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lamia","family":"Azizi","sequence":"first","affiliation":[{"name":"Department of Radiology, University of Balamand, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Karam","family":"Karam","sequence":"first","affiliation":[{"name":"Department of Gastroenterology and Hepatology, University of Balamand, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Emile","family":"Dabaj","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynecology, University of Balamand, Beirut, Lebanon"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"10397","published-online":{"date-parts":[[2026,2,23]]},"reference":[{"key":"10.12890\/2026_006209_ref1","doi-asserted-by":"crossref","unstructured":"Tanoglu FB, Karakus SS, Karakus R, Akgun N, Ustun YE, Ates S, et al. Endometrioma and mature cystic teratoma as collision tumors of the ovary: a case series and literature review. Int J Gynecol Pathol 2026;45:142\u2013151. doi: 10.1097\/PGP.0000000000001147","DOI":"10.1097\/PGP.0000000000001147"},{"key":"10.12890\/2026_006209_ref2","doi-asserted-by":"crossref","unstructured":"Cong L, Wang S, Yeung SY, Lee JHS, Chung JPW, Chan DYL. Mature cystic teratoma: an integrated review. Int J Mol Sci 2023;24:6141. doi: 10.3390\/ijms24076141","DOI":"10.3390\/ijms24076141"},{"key":"10.12890\/2026_006209_ref3","doi-asserted-by":"crossref","unstructured":"Matalliotakis M, Matalliotaki C, Tsakiridis I, Dagklis T, Michos G, Romanos A, et al. Co-existence of Ovarian Teratomas With Other Gynecological Tumors. Cureus 2024;16:e58068. doi: 10.7759\/cureus.58068","DOI":"10.7759\/cureus.58068"},{"key":"10.12890\/2026_006209_ref4","doi-asserted-by":"crossref","unstructured":"Vaduva CC, Dira L, Boldeanu L, Serbanescu MS, Carp-Veliscu A. A narrative review regarding implication of ovarian endometriomas in infertility. Life (Basel) 2025;15:161. doi: 10.3390\/life15020161","DOI":"10.3390\/life15020161"},{"key":"10.12890\/2026_006209_ref5","doi-asserted-by":"crossref","unstructured":"Matalliotakis M, Matalliotaki C, Zervou MI, Krithinakis K, Goulielmos GN, Kalogiannidis I, et al. Retrospective evaluation of pathological results among women with ovarian endometriomas versus teratomas. Mol Clin Oncol 2019;10:592\u2013596. doi: 10.3892\/mco.2019.1844","DOI":"10.3892\/mco.2019.1844"},{"key":"10.12890\/2026_006209_ref6","doi-asserted-by":"crossref","unstructured":"Shams F, Ahmed S, Habib M, Anjum AS. Endometrioma coexisting with mature cystic teratoma in a single ovary: a rare presentation. J Ayub Med Coll Abbottabad 2024;36:447\u2013450. doi: 10.55519\/JAMC-02-12623","DOI":"10.55519\/JAMC-02-12623"},{"key":"10.12890\/2026_006209_ref7","doi-asserted-by":"crossref","unstructured":"Song J, Martin C. A rare case of a large composite endometrioma\u2013mature cystic teratoma: the importance of surgical treatment and pathologic diagnosis. Reprod Med 2024;5:280\u2013287. doi: 10.3390\/reprodmed5040024","DOI":"10.3390\/reprodmed5040024"},{"key":"10.12890\/2026_006209_ref8","doi-asserted-by":"crossref","unstructured":"Rokhgireh S, Mehdizadehkashi A, Tahermanesh K, Gorginzadeh M. Association of endometrioma with ovarian teratoma and mucinous cystadenoma in a patient diagnosed with endometriosis: a case report. World J Obstet Gynecol 2019;8:8\u201312. doi: 10.5317\/wjog.v8.i2.8","DOI":"10.5317\/wjog.v8.i2.8"},{"key":"10.12890\/2026_006209_ref9","doi-asserted-by":"crossref","unstructured":"Balint O, Secosan C, Pirtea L, Grigoras D. Rare association between an endometrioma and a mature cystic teratoma on the same ovary in a postmenopausal woman: a case report and review of literature. J Gynecol Womens Health 2020;18:555982. doi: 10.19080\/JGWH.2020.18.555982","DOI":"10.19080\/JGWH.2020.18.555982"},{"key":"10.12890\/2026_006209_ref10","doi-asserted-by":"crossref","unstructured":"Darouichi M, Tille JC, Dubuisson J, Jovanovic S. Coexistence of mature cystic teratoma and endometrioma in an ovarian cyst. 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