{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T03:54:34Z","timestamp":1787630074019,"version":"build-2736575974"},"reference-count":23,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T00:00:00Z","timestamp":1770940800000},"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. Oncol."],"abstract":"<jats:p>Retroperitoneal Sarcomas are rare malignancies that comprise 1%\u20132% of all malignant tumors. Among them, Low-Grade Fibromyxoid Sarcoma (LGFMS) and Sclerosing Epithelioid Fibrosarcoma (SEF) are ultra-rare sarcomas, especially in retroperitoneum. Hybrid LGFMS\/SEF is even rarer, with limited cases reported in literature. We present the case of a 63-years old male with complaints on left hypochondrial discomfort, weight loss, and generalized weakness. Imaging revealed a large retroperitoneal mass with suspicion of local invasion. The patient underwent en-bloc surgical resection, including distal pancreatectomy, splenectomy, and left adrenalectomy. Histopathological examination confirmed a hybrid LGFMS\/SEF with characteristic biphasic morphology. Hybrid LGFMS\/SEF tumors exhibit features of both LGFMS and SEF sarcoma subtypes. Complete surgical resection remains the primary treatment strategy for localized disease. Because of the rarity of the disease, long-term surveillance is recommended. For advanced diseases, there are limited efficient available treatments necessitating the research of targeted therapies.<\/jats:p>","DOI":"10.3389\/fonc.2026.1673104","type":"journal-article","created":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T05:22:54Z","timestamp":1770960174000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Case Report: Hybrid low-grade fibromyxoid sarcoma and sclerosing epithelioid fibrosarcoma of the retroperitoneum"],"prefix":"10.3389","volume":"16","author":[{"given":"Zhandos","family":"Burkitbayev","sequence":"first","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aruzhan","family":"Zhaksylyk","sequence":"additional","affiliation":[{"name":"Department of Surgery, School of Medicine, Nazarbayev University","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Baiduisen","family":"Ussipbekov","sequence":"additional","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Talgat","family":"Uskenbayev","sequence":"additional","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Altay","family":"Kerimkulov","sequence":"additional","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u0422omiris","family":"Sarina","sequence":"additional","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Artem","family":"Gogolev","sequence":"additional","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saltanat","family":"Bolsinbekova","sequence":"additional","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aigerim","family":"Sipenova","sequence":"additional","affiliation":[{"name":"Department of Surgery, National Research Oncology Center","place":["Astana, Kazakhstan"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,2,13]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1002\/jso.2930190410","article-title":"Results of the national soft-tissue sarcoma 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