{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,21]],"date-time":"2026-01-21T06:04:40Z","timestamp":1768975480138,"version":"3.49.0"},"reference-count":20,"publisher":"S. Karger AG","issue":"1","license":[{"start":{"date-parts":[[2025,12,15]],"date-time":"2025-12-15T00:00:00Z","timestamp":1765756800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2025,12,15]],"date-time":"2025-12-15T00:00:00Z","timestamp":1765756800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Case Rep Oncol"],"abstract":"<jats:p>Introduction: The synchronous presentation of a colorectal adenocarcinoma and a gastrointestinal stromal tumor (GIST) is a rare clinical event that poses significant diagnostic and therapeutic challenges. These two malignancies arise from distinct histogenetic origins and are typically managed with different treatment paradigms. The incidental discovery of a GIST during the workup for a more symptomatic adenocarcinoma complicates surgical planning and requires a comprehensive, multidisciplinary approach to ensure optimal oncologic outcomes. Case Presentation: An 85-year-old female presented with a 6-month history of debilitating fecal incontinence, tenesmus, rectal bleeding, and a 13 kg weight loss. Diagnostic evaluation, including imaging and endoscopy, identified two separate lesions: a large, ulcerated mass in the mid-rectum and a pedunculated mass in the sigmoid colon. Biopsies with immunohistochemical analysis confirmed the rectal mass as a moderately differentiated adenocarcinoma (CK20+, CDX2+) and the sigmoid mass as a spindle-cell neoplasm consistent with a GIST (CD117+, DOG1+). Due to the local invasion of the rectal cancer into the posterior vaginal wall, the patient underwent an open en bloc abdominoperineal resection, which included a hysterectomy, bilateral salpingo-oophorectomy, posterior vaginectomy, and sigmoidectomy. Final pathology confirmed a pT3N0 rectal adenocarcinoma with negative margins and a completely resected 3.5 cm low-risk sigmoid GIST. The patient was followed for 24 months with no evidence of recurrence of either tumor. Postoperatively, her presenting symptoms of tenesmus and bleeding resolved. Conclusion: This case demonstrates the critical role of immunohistochemistry in confirming synchronous primary tumors. For complex, locally advanced disease, radical upfront en bloc resection remains the gold standard for achieving curative-intent, negative margins, even in the elderly.<\/jats:p>","DOI":"10.1159\/000550095","type":"journal-article","created":{"date-parts":[[2025,12,15]],"date-time":"2025-12-15T17:00:40Z","timestamp":1765818040000},"page":"127-135","source":"Crossref","is-referenced-by-count":0,"title":["Synchronous Rectal Adenocarcinoma and Sigmoid Gastrointestinal Stromal Tumor: A Case Report"],"prefix":"10.1159","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-3173-1942","authenticated-orcid":false,"given":"Ahmad","family":"Al-Bitar","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-8937-4919","authenticated-orcid":false,"given":"Yaman","family":"Almkaky","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5418-3186","authenticated-orcid":false,"given":"Maher","family":"Saifo","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2025,12,15]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","DOI":"10.1002\/cam4.1991"},{"key":"ref2","doi-asserted-by":"publisher","DOI":"10.1177\/17588359211023278"},{"key":"ref3","doi-asserted-by":"publisher","DOI":"10.1186\/1477-7819-7-33"},{"key":"ref4","doi-asserted-by":"publisher","DOI":"10.5306\/wjco.v6.i6.225"},{"key":"ref5","doi-asserted-by":"publisher","DOI":"10.1159\/000548545"},{"key":"ref6","doi-asserted-by":"publisher","DOI":"10.12659\/ajcr.894845"},{"key":"ref7","doi-asserted-by":"publisher","DOI":"10.3748\/wjg.v24.i18.1925"},{"key":"ref8","doi-asserted-by":"publisher","DOI":"10.1016\/S1470-2045(20)30269-2"},{"key":"ref9","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijscr.2014.06.012"},{"key":"ref10","doi-asserted-by":"publisher","DOI":"10.3390\/cancers13040705"},{"key":"ref11","doi-asserted-by":"publisher","DOI":"10.1186\/s13256-025-05423-8"},{"key":"ref12","doi-asserted-by":"publisher","DOI":"10.1302\/0301-620X.100B6.BJJ-2017-1212.R1"},{"key":"ref13","doi-asserted-by":"publisher","DOI":"10.1097\/DCR.0b013e31827a7868"},{"key":"ref14","doi-asserted-by":"publisher","DOI":"10.1200\/JCO.2022.40.36_suppl.359881"},{"key":"ref15","doi-asserted-by":"publisher","DOI":"10.3390\/jcm10051057"},{"key":"ref16","doi-asserted-by":"publisher","DOI":"10.4251\/wjgo.v15.i10.1807"},{"key":"ref17","doi-asserted-by":"publisher","DOI":"10.18632\/oncotarget.3108"},{"key":"ref18","doi-asserted-by":"publisher","DOI":"10.3748\/wjg.v12.i33.5360"},{"key":"ref19","doi-asserted-by":"publisher","DOI":"10.1002\/cncr.33630"},{"key":"ref20","doi-asserted-by":"publisher","DOI":"10.1634\/theoncologist.2019-0418"}],"container-title":["Case Reports in Oncology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000550095","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T17:01:04Z","timestamp":1768928464000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000550095"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,15]]},"references-count":20,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1,1]]}},"URL":"https:\/\/doi.org\/10.1159\/000550095","archive":["Portico"],"relation":{"is-supplemented-by":[{"id-type":"doi","id":"10.6084\/m9.figshare.30883967","asserted-by":"subject"}]},"ISSN":["1662-6575"],"issn-type":[{"value":"1662-6575","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,15]]}}}