{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T13:49:15Z","timestamp":1782481755474,"version":"3.54.5"},"reference-count":15,"publisher":"BMJ","issue":"6","license":[{"start":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T00:00:00Z","timestamp":1782432000000},"content-version":"unspecified","delay-in-days":25,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,6,16]]},"published-print":{"date-parts":[[2026,6]]},"abstract":"<jats:p>IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder that typically presents with multiorgan involvement. Herein, we report a rare phenotype in which the disease was confined solely to the kidneys and lungs. A man in his 60s presented with a 6-month history of cough and exertional dyspnoea. Imaging revealed bilateral renal enlargement with decreased enhancement, compatible with IgG4-related kidney disease, whereas the pulmonary findings were atypical for IgG4-related lung disease and radiologically mimicked non-specific interstitial pneumonia, making it difficult to determine whether the pulmonary lesions represented part of the same disease process or a separate interstitial lung disease. Serological findings indicated IgG4-RD. To clarify whether both organs were affected by a single systemic process, a thoracoscopic surgical lung biopsy was performed. The histopathological examination confirmed IgG4-positive plasma cell-rich inflammation establishing the diagnosis of IgG4-RD. Corticosteroid therapy resulted in radiological and clinical improvements of both organs. Histopathological evaluation of the lung lesions enabled a unified diagnosis of both the renal and pulmonary manifestations. A stepwise diagnostic approach using lung biopsy facilitated accurate diagnosis and effective treatment.<\/jats:p>","DOI":"10.1136\/bcr-2026-273528","type":"journal-article","created":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T13:10:40Z","timestamp":1782479440000},"page":"e273528","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Isolated pulmonary and renal IgG4-related disease: a rare dual-organ presentation diagnosed via video-assisted thoracoscopic surgery"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-4046-9990","authenticated-orcid":false,"given":"Natsumi","family":"Yazaki","sequence":"first","affiliation":[{"name":"Internal Medicine, Japan Community Health Care Organization Saitama Medical Center, Saitama-shi, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuka","family":"Katsurada","sequence":"additional","affiliation":[{"name":"Department 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