{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,22]],"date-time":"2026-08-22T12:22:45Z","timestamp":1787401365185,"version":"build-2736575974"},"reference-count":28,"publisher":"Oxford University Press (OUP)","issue":"8","license":[{"start":{"date-parts":[[2026,8,12]],"date-time":"2026-08-12T00:00:00Z","timestamp":1786492800000},"content-version":"vor","delay-in-days":11,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,8,3]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Dedifferentiated endometrial carcinoma (DEC) is a rare and aggressive uterine malignancy composed of low-grade endometrioid carcinoma admixed with an undifferentiated component and is associated with a poorer prognosis than conventional high-grade endometrioid carcinoma. Its synchronous occurrence with uterine leiomyosarcoma as a collision tumour is exceptionally rare.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case Presentation<\/jats:title>\n                    <jats:p>A 74-year-old postmenopausal woman presented with abnormal uterine bleeding. Imaging revealed an endometrial mass, and she underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy. Histopathological examination demonstrated DEC with subclonal mismatch repair (MMR) deficiency and a morphologically distinct leiomyosarcoma. Immunohistochemistry showed loss of MLH1 and PMS2 expression in approximately 40% of tumour cells within the dedifferentiated component, with retained expression in the low-grade component. MLH1 promoter hypermethylation analysis demonstrated a methylation level of 55%, supporting a sporadic origin. A morphologically and immunophenotypically distinct uterine leiomyosarcoma was identified within the same specimen, consistent with a true collision tumour. The diagnosis was confirmed through comprehensive morphological, immunohistochemical, and molecular analyses. Postoperative imaging demonstrated nodal disease, and the patient subsequently received adjuvant therapy. At 1-year follow-up, she remained in complete remission.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This rare collision tumour highlights the importance of integrated histopathological and molecular evaluation, particularly in recognising subclonal MMR deficiency and tumour heterogeneity.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/omcr\/omag155","type":"journal-article","created":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T11:43:16Z","timestamp":1785843796000},"source":"Crossref","is-referenced-by-count":0,"title":["MMR deficient dedifferentiated endometrial carcinoma with synchronous uterine leiomyosarcoma: a rare collision tumour\u2014case report and literature review"],"prefix":"10.1093","volume":"2026","author":[{"given":"Mohammed Sami","family":"Saeed","sequence":"first","affiliation":[{"name":"Department of Pathology, King's Mill Hospital, Sherwood Forest Hospitals NHS Foundation Trust, Mansfield Road, Sutton-in-Ashfield, Nottinghamshire NG17 4JL ,","place":["United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hafza Asma","family":"Adnan","sequence":"additional","affiliation":[{"name":"Department of Pathology, King's Mill Hospital, Sherwood Forest Hospitals NHS Foundation Trust, Mansfield Road, Sutton-in-Ashfield, Nottinghamshire NG17 4JL ,","place":["United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-7625-5206","authenticated-orcid":false,"given":"Adzmi Hakim","family":"Rahman","sequence":"additional","affiliation":[{"name":"Department of Pathology, King's Mill Hospital, Sherwood Forest Hospitals NHS Foundation Trust, Mansfield Road, Sutton-in-Ashfield, Nottinghamshire NG17 4JL ,","place":["United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Samiya","family":"Ibrahim","sequence":"additional","affiliation":[{"name":"Department of Pathology, Nottingham University Hospitals NHS Trust, City Hospital Campus, Hucknall Road, Nottingham, Nottinghamshire NG5 1PB, \u00a0","place":["United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Awani","family":"Patel","sequence":"additional","affiliation":[{"name":"Department of Radiology, King's Mill Hospital, Sherwood Forest Hospitals NHS Foundation Trust, Mansfield Road, Sutton-in-Ashfield, Nottinghamshire NG17 4JL ,","place":["United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2026,8,12]]},"reference":[{"key":"2026082207313601600_ref1","first-page":"1","article-title":"Undifferentiated carcinoma of the endometrium: a review of 30 cases","volume":"25","author":"Silva","year":"2006","journal-title":"Int J Gynecol 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