{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T06:26:59Z","timestamp":1786602419309,"version":"build-2736575974"},"reference-count":23,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T00:00:00Z","timestamp":1786579200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Surg."],"abstract":"<jats:p>Intestinal endometriosis is a benign gynecological condition that frequently involves the rectosigmoid colon. Its synchronous occurrence with colorectal cancer is exceptionally rare and diagnostically challenging, particularly when mimicking a second primary malignancy. We report a case of a 48-year-old woman presenting with altered bowel habits. Colonoscopy revealed synchronous lesions: an adenocarcinoma at the hepatic flexure and a suspicious mass in the sigmoid colon. Repeated biopsies of the sigmoid lesion were inconclusive, ranging from dysplasia to chronic inflammation, raising concern for a second primary tumor. The patient underwent right hemicolectomy with partial sigmoidectomy. Intraoperative frozen section unexpectedly identified endometriosis, subsequently confirmed by definitive pathology and immunohistochemistry. At 12-month follow-up, the patient remained well with no evidence of recurrence.<\/jats:p>","DOI":"10.3389\/fsurg.2026.1923049","type":"journal-article","created":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T05:32:04Z","timestamp":1786599124000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Synchronous right colon adenocarcinoma and sigmoid endometriosis mimicking a second primary carcinoma: a case report"],"prefix":"10.3389","volume":"13","author":[{"given":"Ke","family":"Yang","sequence":"first","affiliation":[{"name":"Department of General Surgery, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang","place":["Sichuan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ping","family":"Li","sequence":"additional","affiliation":[{"name":"Department of General Surgery, Mianyang Central Hospital, School of Medicine, 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