{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T15:51:17Z","timestamp":1782489077267,"version":"3.54.5"},"reference-count":15,"publisher":"BMJ","issue":"4","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,3,31]]},"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:p>In this article, we report a case of idiopathic multicentric Castleman disease (iMCD) with an atypical manifestation in a man in his early 50s, whose first symptoms included recurrent episodes of pancreatitis, retroperitoneal fibrosis and lymphadenopathy. These features are more commonly associated with IgG4-related disease (IgG4-RD). Although clinical findings were suggestive of IgG4-RD, IgG4 levels were within the normal range, along with a histopathological examination, ultimately leading to an iMCD diagnosis, showing characteristic vascular hyperplasia and a polyclonal plasma cell infiltrate showing no signs of IgG4+ plasma cells. In addition, the patient showed improvement with siltuximab, an interleukin-6 inhibitor drug specific for iMCD. This challenging case enhances the importance of combining clinical evaluation, serological testing and histopathological analysis to establish a definitive diagnosis.<\/jats:p>","DOI":"10.1136\/bcr-2025-267049","type":"journal-article","created":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T12:15:14Z","timestamp":1776773714000},"page":"e267049","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Idiopathic multicentric Castleman disease in a patient with an IgG4-related disease phenotype"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-6814-8375","authenticated-orcid":false,"given":"Juan","family":"Sastre Ortega","sequence":"first","affiliation":[{"name":"Department of Hematology and Hemotherapy of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carlos","family":"Martinez-Caballero","sequence":"additional","affiliation":[{"name":"Systemic Autoimmune Diseases Unit of the Hospital de M\u00f3stoles, Hospital Universitario de Mostoles, Mostoles, Spain"},{"name":"Department of Internal Medicine of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Community of Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marta","family":"Rueda Herrera","sequence":"additional","affiliation":[{"name":"Systemic Autoimmune Diseases Unit of the Hospital de M\u00f3stoles, Hospital Universitario de Mostoles, Mostoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcos Jos\u00e9","family":"Carrillo Pohl","sequence":"additional","affiliation":[{"name":"Department of Pathological Anatomy of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Community of Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariana","family":"Cerrato Salas","sequence":"additional","affiliation":[{"name":"Department of Hematology and Hemotherapy of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ane","family":"Brieva L\u00f3pez","sequence":"additional","affiliation":[{"name":"Department of Hematology and Hemotherapy of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pavel Manuel","family":"Acevedo P\u00e9rez","sequence":"additional","affiliation":[{"name":"Department of Hematology and Hemotherapy of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cristina","family":"Diego Hern\u00e1ndez","sequence":"additional","affiliation":[{"name":"Department of Pathological Anatomy of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Community of Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sonia","family":"Hernandez-Puche","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine of the Hospital de M\u00f3stoles, Hospital Universitario de M\u00f3stoles, M\u00f3stoles, Community of Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amalia","family":"Mu\u00f1ana Fuentes","sequence":"additional","affiliation":[{"name":"Systemic Autoimmune Diseases Unit of the Hospital de M\u00f3stoles, Hospital Universitario de Mostoles, Mostoles, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,4,21]]},"reference":[{"key":"2026062608154809000_19.4.e267049.1","doi-asserted-by":"crossref","unstructured":"Dispenzieri A . Castleman disease. In: Ansell SM , ed. Rare hematological malignancies. Boston, MA: Springer US, 2008: 293\u2013330. 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