{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T15:53:44Z","timestamp":1777046024649,"version":"3.51.4"},"reference-count":11,"publisher":"BMJ","issue":"4","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,4,1]]},"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:p>Solitary extramedullary plasmacytoma of the kidney is an exceptionally rare plasma cell neoplasm and may closely mimic renal cell carcinoma on imaging. A woman in her late 50s was incidentally found to have a left renal mass during evaluation for non-specific abdominal discomfort. Cross-sectional imaging revealed a multiloculated cystic renal lesion with enhancing walls, raising concern for primary renal malignancy. CT-guided biopsy demonstrated sheets of plasma cells with kappa light-chain restriction. Comprehensive evaluation, including serum studies, positron emission tomography\u2013CT and bone marrow biopsy, showed no evidence of systemic multiple myeloma, confirming the diagnosis of solitary renal plasmacytoma. The patient was treated with definitive external beam radiotherapy and achieved complete radiological resolution, with no evidence of progression on follow-up. This case highlights an important diagnostic pitfall and emphasises the value of early tissue diagnosis to avoid unnecessary nephrectomy and allow curative local therapy.<\/jats:p>","DOI":"10.1136\/bcr-2026-272579","type":"journal-article","created":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T14:30:19Z","timestamp":1777041019000},"page":"e272579","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Solitary renal plasmacytoma presenting as a left renal mass mimicking renal cell carcinoma"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-9377-9218","authenticated-orcid":false,"given":"Edward","family":"Mwarangu","sequence":"first","affiliation":[{"name":"Internal Medicine, The University of Kansas School of Medicine-Wichita, Wichita, Kansas, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fady","family":"El Tom","sequence":"additional","affiliation":[{"name":"The University of Kansas School of Medicine-Wichita, Wichita, Kansas, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joseph","family":"Moore","sequence":"additional","affiliation":[{"name":"Cancer Center of Kansas, Wichita, Kansas, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2026,4,24]]},"reference":[{"key":"2026042407301224000_19.4.e272579.1","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1097-0142(19990601)85:11<2305::AID-CNCR2>3.0.CO;2-3"},{"key":"2026042407301224000_19.4.e272579.2","article-title":"Primary plasmacytoma of the kidney","volume":"2013","author":"Spence","year":"2013","journal-title":"Case Rep Urol"},{"key":"2026042407301224000_19.4.e272579.3","doi-asserted-by":"publisher","DOI":"10.1016\/j.clon.2004.02.007"},{"key":"2026042407301224000_19.4.e272579.4","doi-asserted-by":"publisher","DOI":"10.1097\/00005792-197605000-00002"},{"key":"2026042407301224000_19.4.e272579.5","doi-asserted-by":"crossref","first-page":"1839","DOI":"10.3892\/ol.2013.1282","article-title":"Renal plasmacytoma: Report of a rare case and review of the literature","volume":"5","author":"Zhang","year":"2013","journal-title":"Oncol Lett"},{"key":"2026042407301224000_19.4.e272579.6","doi-asserted-by":"publisher","DOI":"10.1038\/bjc.1997.162"},{"key":"2026042407301224000_19.4.e272579.7","doi-asserted-by":"publisher","DOI":"10.1016\/S0889-8588(05)70124-6"},{"key":"2026042407301224000_19.4.e272579.8","doi-asserted-by":"publisher","DOI":"10.1016\/S1470-2045(14)70442-5"},{"key":"2026042407301224000_19.4.e272579.9","doi-asserted-by":"crossref","DOI":"10.1186\/s13045-017-0549-1","article-title":"Diagnosis, treatment, and response assessment in solitary plasmacytoma: updated recommendations from a European Expert Panel","volume":"11","author":"Caers","year":"2018","journal-title":"J Hematol Oncol"},{"key":"2026042407301224000_19.4.e272579.10","doi-asserted-by":"crossref","first-page":"373","DOI":"10.1182\/asheducation-2005.1.373","article-title":"Solitary bone and extramedullary plasmacytoma","volume":"2005","author":"Weber","year":"2005","journal-title":"Hematology Am Soc Hematol Educ Program"},{"key":"2026042407301224000_19.4.e272579.11","doi-asserted-by":"crossref","first-page":"2037","DOI":"10.1182\/blood.V96.6.2037","article-title":"Solitary plasmacytoma of bone and asymptomatic multiple myeloma","volume":"96","author":"Dimopoulos","year":"2000","journal-title":"Blood"}],"container-title":["BMJ Case Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bcr-2026-272579","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T14:30:21Z","timestamp":1777041021000},"score":1,"resource":{"primary":{"URL":"https:\/\/casereports.bmj.com\/lookup\/doi\/10.1136\/bcr-2026-272579"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4]]},"references-count":11,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,4,24]]},"published-print":{"date-parts":[[2026,4]]}},"alternative-id":["10.1136\/bcr-2026-272579"],"URL":"https:\/\/doi.org\/10.1136\/bcr-2026-272579","relation":{},"ISSN":["1757-790X"],"issn-type":[{"value":"1757-790X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4]]}}}