{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:44:23Z","timestamp":1760060663935,"version":"build-2065373602"},"reference-count":36,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2025,9,10]],"date-time":"2025-09-10T00:00:00Z","timestamp":1757462400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background: Collision tumors, especially in the ovary, are a rare phenomenon where two distinct types of tumors develop adjacent to each other within the same organ but remain separate histologically. We present a case of the first collision ovarian tumor in a 14-year-old girl consisting of a combined tumor and a mature teratoma. Case Report: A 14-year-old girl presented with abdominal swelling for the past three months, without other symptoms. Ultrasound (US) examination of the abdomen revealed a large cystic mass with multiple septa, filling the entire abdomen from the diaphragm to the pelvis. Magnetic resonance imaging (MRI) showed an intraperitoneal mass, inseparable from the right ovary, measuring 22 cm \u00d7 13 cm \u00d7 30 cm. Serum tumor markers were within normal limits. The tumor mass was completely extirpated along with the fallopian tube. Histological and immunohistochemical analysis determined that it was a mucinous cystadenocarcinoma, characterized by a transition pattern from benign and borderline components to an adenocarcinoma component with a smaller mature teratoma. Six-month follow-up revealed no recurrence or postoperative complications. Conclusions: As the first documented case, this case provides valuable insights into pediatric ovarian neoplasms, guiding future diagnostic and therapeutic approaches.<\/jats:p>","DOI":"10.3390\/jcm14186387","type":"journal-article","created":{"date-parts":[[2025,9,10]],"date-time":"2025-09-10T12:04:55Z","timestamp":1757505895000},"page":"6387","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Ovarian Collision Tumor in a Pediatric Patient: A Mature Teratoma Associated with a Combined Tumor Containing a Mucinous Cystadenocarcinoma Component"],"prefix":"10.3390","volume":"14","author":[{"given":"Dorotea","family":"Kereti\u0107","sequence":"first","affiliation":[{"name":"Department of Pediatric Surgery, Children\u2019s Hospital Zagreb, Ulica Vjekoslava Klai\u0107a 16, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ivan","family":"Petra\u010di\u0107","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, Children\u2019s Hospital Zagreb, Ulica Vjekoslava Klai\u0107a 16, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Silvija","family":"Ma\u0161i\u0107 Binder","sequence":"additional","affiliation":[{"name":"School of Medicine, University of Zagreb, \u0160alata 3, 10000 Zagreb, Croatia"},{"name":"Ljudevit Jurak Clinical Department of Pathology and Cytology, University Clinical Hospital Center Sestre Milosrdnice, Vinogradska cesta 29, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Monika","family":"Ulamec","sequence":"additional","affiliation":[{"name":"School of Medicine, University of Zagreb, \u0160alata 3, 10000 Zagreb, Croatia"},{"name":"Ljudevit Jurak Clinical Department of Pathology and Cytology, University Clinical Hospital Center Sestre Milosrdnice, Vinogradska cesta 29, 10000 Zagreb, Croatia"},{"name":"Scientific Centre of Excellence for Reproductive and Regenerative Medicine, School of Medicine, University of Zagreb, \u0160alata 3, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrea","family":"Plavec \u017divko","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Polyclinic for Pediatric and Adolescent Gynecology and Reproductive Health, Children\u2019s Hospital Zagreb, Ulica Vjekoslava Klai\u0107a 16, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jasminka","family":"Stepan Giljevi\u0107","sequence":"additional","affiliation":[{"name":"Department of Pediatric Oncology and Hematology, Children\u2019s Hospital Zagreb, Ulica Vjekoslava Klai\u0107a 16, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Aleksandra","family":"Bonevski","sequence":"additional","affiliation":[{"name":"Department of Pediatric Oncology and Hematology, Children\u2019s Hospital Zagreb, Ulica Vjekoslava Klai\u0107a 16, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7675-7064","authenticated-orcid":false,"given":"Dubravko","family":"Habek","sequence":"additional","affiliation":[{"name":"School of Medicine, University of Zagreb, \u0160alata 3, 10000 Zagreb, Croatia"},{"name":"Department of Obstetrics and Gynecology, Clinical Hospital Merkur, Zaj\u010deva ulica 19, 10000 Zagreb, Croatia"},{"name":"School of Medicine, Catholic University of Croatia, Ilica 242, 10000 Zagreb, Croatia"},{"name":"Croatian Academy of Medical Sciences, Kaptol 15, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4218-6184","authenticated-orcid":false,"given":"Marko","family":"Ba\u0161kovi\u0107","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, Children\u2019s Hospital Zagreb, Ulica Vjekoslava Klai\u0107a 16, 10000 Zagreb, Croatia"},{"name":"School of Medicine, University of Zagreb, \u0160alata 3, 10000 Zagreb, Croatia"},{"name":"Scientific Centre of Excellence for Reproductive and Regenerative Medicine, School of Medicine, University of Zagreb, \u0160alata 3, 10000 Zagreb, Croatia"},{"name":"School of Medicine, Catholic University of Croatia, Ilica 242, 10000 Zagreb, Croatia"},{"name":"Croatian Academy of Medical Sciences, Kaptol 15, 10000 Zagreb, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1111\/aogs.12598","article-title":"Pediatric ovarian neoplastic tumors: Incidence, age at presentation, tumor markers and outcome","volume":"94","author":"Taskinen","year":"2015","journal-title":"Acta Obstet. 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