{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T05:45:55Z","timestamp":1775108755062,"version":"3.50.1"},"reference-count":17,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T00:00:00Z","timestamp":1775088000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Peking Union Medical College Hospital Undergraduate Educational Reform Project","award":["2025bkjg005"],"award-info":[{"award-number":["2025bkjg005"]}]},{"name":"Peking Union Medical College Hospital Undergraduate Educational Reform Project","award":["2024bkjg015"],"award-info":[{"award-number":["2024bkjg015"]}]},{"name":"National Multidisciplinary Cooperative Diagnosis and Treatment Capacity Building Project for Major Diseases","award":["ZK12101"],"award-info":[{"award-number":["ZK12101"]}]},{"name":"Capital\u2019s Funds for Health Improvement and Research","award":["2024-2-4017"],"award-info":[{"award-number":["2024-2-4017"]}]},{"name":"National High Level Hospital Clinical Research Funding","award":["2025-PUMCH-A-073"],"award-info":[{"award-number":["2025-PUMCH-A-073"]}]},{"name":"National High Level Hospital Clinical Research Funding","award":["2025-PUMCH-A-072"],"award-info":[{"award-number":["2025-PUMCH-A-072"]}]},{"name":"National High Level Hospital Clinical Research Funding","award":["2025-PUMCH-C-018"],"award-info":[{"award-number":["2025-PUMCH-C-018"]}]},{"name":"Nonprofit Central Research Institute Fund of Chinese Academy of Medical Sciences","award":["2018PT32014"],"award-info":[{"award-number":["2018PT32014"]}]},{"name":"CAMS Innovation Fund for Medical Sciences","award":["2024-I2M-ZD-001"],"award-info":[{"award-number":["2024-I2M-ZD-001"]}]},{"name":"CAMS Innovation Fund for Medical Sciences","award":["2021-I2M-1-002"],"award-info":[{"award-number":["2021-I2M-1-002"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["82573412"],"award-info":[{"award-number":["82573412"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["82173074)"],"award-info":[{"award-number":["82173074)"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004826","name":"Beijing Natural Science Foundation","doi-asserted-by":"publisher","award":["7232127"],"award-info":[{"award-number":["7232127"]}],"id":[{"id":"10.13039\/501100004826","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:p>IgG4-related autoimmune pancreatitis (AIP) can resemble pancreatic ductal adenocarcinoma (PDAC), but it typically presents as a solid mass rather than a cystic-solid lesion. We report a rare case of AIP in a middle-aged man with a long-standing pancreatic tail mass that gradually enlarged and developed a cystic-solid configuration. Photon-counting CT showed a non-enhancing cystic component and a progressively enhancing solid portion with apparent invasion of adjacent organs, while FDG-PET\/CT demonstrated marked metabolic activity, all strongly suggestive of malignancy. Serum IgG4 levels were normal and no extrapancreatic IgG4-related involvement was present. The patient declined biopsy and underwent radical surgery; histopathology revealed dense fibrosis, pancreatic atrophy, and lymphoplasmacytic infiltration consistent with IgG4-related AIP, with no evidence of cancer. This case highlights that atypical cystic-solid AIP can closely mimic invasive PDAC even with advanced imaging techniques, underscoring the importance of recognizing such rare presentations to avoid unnecessary radical resection.<\/jats:p>","DOI":"10.3389\/fmed.2026.1756102","type":"journal-article","created":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T04:21:16Z","timestamp":1775103676000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: IgG4-related autoimmune pancreatitis presenting as an infiltrative cystic-solid pancreatic mass: lessons from a diagnostic pitfall"],"prefix":"10.3389","volume":"13","author":[{"given":"Ran","family":"Xiao","sequence":"first","affiliation":[{"name":"Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences","place":["Beijing, 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China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jingyi","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences","place":["Beijing, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mingliang","family":"Bai","sequence":"additional","affiliation":[{"name":"Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences","place":["Beijing, China"]},{"name":"Department of Surgery, Zhouqu County People\u2019s Hospital","place":["Longnan, Gansu, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiashu","family":"Han","sequence":"additional","affiliation":[{"name":"Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical 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