{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T07:03:58Z","timestamp":1784099038507,"version":"3.55.0"},"reference-count":14,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T00:00:00Z","timestamp":1784073600000},"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. Immunol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Immune checkpoint inhibitors (ICIs) can induce a broad spectrum of immune-related adverse events (irAEs), including rare fibroinflammatory autoimmune manifestations. IgG4-related disease (IgG4-RD) has only exceptionally been described following dual ICI therapy.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case presentation<\/jats:title>\n                    <jats:p>We report a 65-year-old man with metastatic clear cell renal carcinoma treated with nivolumab plus ipilimumab after nephrectomy. Despite initial radiologic stability, follow-up computed tomography revealed newly developed mass-like lesions in the solitary remaining kidney, raising suspicion of metastatic progression. CT-guided biopsy demonstrated subacute pyelonephritis, acute tubular injury, storiform fibrosis, and dense IgG4-positive plasma cell infiltration consistent with IgG4-RD. Because glucocorticoids were considered potentially detrimental to antitumor immune surveillance, rituximab was selected as steroid-sparing first-line therapy. Two infusions of rituximab (1000 mg each) led to radiologic stabilization\/regression of renal lesions while pulmonary metastases remained under oncologic control.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This case highlights IgG4-RD as a rare but clinically important underrecognized irAE of dual ICI therapy that may mimic malignant progression. Histologic confirmation is crucial, and B-cell depletion with rituximab may represent an effective treatment strategy when preservation of antitumor immunity is a priority.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2026.1884821","type":"journal-article","created":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T06:05:24Z","timestamp":1784095524000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Immune checkpoint inhibitor-induced IgG4-related disease mimicking renal metastatic progression: successful steroid-sparing management with rituximab"],"prefix":"10.3389","volume":"17","author":[{"given":"Mayara Elisa","family":"Bonatto","sequence":"first","affiliation":[{"name":"Institute of Rheumatology and Department of Rheumatology, 1st Faculty of Medicine, Charles University","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan","family":"Dvo\u0159\u00e1k","sequence":"additional","affiliation":[{"name":"Department of Oncology, Faculty Hospital Kr\u00e1lovsk\u00e9 Vinohrady","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marek","family":"Koll\u00e1r","sequence":"additional","affiliation":[{"name":"Department of Pathology, Institute for Clinical and Experimental Medicine","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"Girsa","sequence":"additional","affiliation":[{"name":"Department of Radiology, Faculty Hospital Kr\u00e1lovsk\u00e9 Vinohrady","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Miroslav","family":"Pr\u016fcha","sequence":"additional","affiliation":[{"name":"Department of Allergology and Clinical Immunology, Hospital na Homolce","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u0160\u00e1rka","family":"Forejtov\u00e1","sequence":"additional","affiliation":[{"name":"Institute of Rheumatology and Department of Rheumatology, 1st Faculty of Medicine, Charles University","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"He\u0159man","family":"Mann","sequence":"additional","affiliation":[{"name":"Institute of Rheumatology and Department of Rheumatology, 1st Faculty of Medicine, Charles University","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ji\u0159\u00ed","family":"Vencovsk\u00fd","sequence":"additional","affiliation":[{"name":"Institute of Rheumatology and Department of Rheumatology, 1st Faculty of Medicine, Charles University","place":["Prague, Czechia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karel","family":"Pavelka","sequence":"additional","affiliation":[{"name":"Institute 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