{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T06:06:20Z","timestamp":1784700380142,"version":"3.55.0"},"reference-count":14,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T00:00:00Z","timestamp":1784678400000},"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:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Sarcomatoid renal cell carcinoma (sRCC) is a rare, highly aggressive malignancy that can closely mimic xanthogranulomatous pyelonephritis (XGP) on clinical, laboratory, and radiological grounds. While sRCC masquerading as XGP has been previously reported, existing literature lacks a structured analysis of the specific features that discriminate these entities and a practical framework for clinical decision-making.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case presentation<\/jats:title>\n                    <jats:p>A 65-year-old female presented with a four-month history of anorexia and one week of postprandial abdominal distension. Contrast-enhanced CT demonstrated right renal enlargement with heterogeneous density, nephrolithiasis, and a bear-paw-like appearance, leading to an initial diagnosis of XGP. However, several features were inconsistent with typical XGP: persistently negative urine and blood cultures, an irregular solid component with heterogeneous arterial-phase enhancement, subtle renal vein irregularity suggestive of vascular invasion, progressive transfusion-requiring anemia, and persistent high fever despite 24 days of escalating broad-spectrum antibiotics (culminating in meropenem plus vancomycin). Repeat CT showed no radiological improvement. Right radical nephrectomy was performed on hospital day 31. Histopathology confirmed sRCC with lymphovascular invasion and a Ki-67 index of 50\u201355%. Despite initial recovery, the patient developed rapid multi-organ metastasis and succumbed to the disease.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>When a presumed renal infection is culture-negative, antibiotic-refractory, associated with progressive anemia, and radiologically non-resolving, malignancy should be suspected early. The presence of an irregular solid enhancing component and vascular involvement on CT are malignancy-specific red flags that should not be overlooked. A bear-paw-like appearance does not exclude RCC. Short-interval failure of antibiotic therapy (7\u201310 days) should trigger surgical exploration or tissue diagnosis rather than prolonged empirical treatment.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fonc.2026.1798397","type":"journal-article","created":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T05:52:15Z","timestamp":1784699535000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Sarcomatoid renal cell carcinoma masquerading as xanthogranulomatous pyelonephritis: a case report"],"prefix":"10.3389","volume":"16","author":[{"given":"Chenzhao","family":"Hua","sequence":"first","affiliation":[{"name":"Department of Urology, Ward One, Shengli Oilfield Central Hospital","place":["Dongying, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tingting","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Urology, Ward Two, Shengli Oilfield Central Hospital","place":["Dongying, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xianqiao","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Nephrology, Shengli Oilfield Central Hospital","place":["Dongying, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shuhua","family":"Duan","sequence":"additional","affiliation":[{"name":"Department of Medical Imaging, Shengli Oilfield Central Hospital","place":["Dongying, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,22]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1016\/S0221-0363(07)89929-X","article-title":"Imagerie de la py\u00e9lon\u00e9phrite xantogranulomateuse","volume":"88","author":"Charrada-Ben Farhat","year":"2007","journal-title":"J 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