{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T11:05:10Z","timestamp":1779966310636,"version":"3.53.1"},"reference-count":10,"publisher":"Springer Science and Business Media LLC","issue":"3","license":[{"start":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T00:00:00Z","timestamp":1774569600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T00:00:00Z","timestamp":1774569600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"DOI":"10.13039\/100019084","name":"Kobe University","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100019084","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Clin J Gastroenterol"],"published-print":{"date-parts":[[2026,6]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>We present a rare case of autoimmune pancreatitis (AIP) confined exclusively to the subepithelial layer in the main pancreatic duct (MPD) without associated pancreatic enlargement or mass formation. A 73-year-old man presented with elevated serum pancreatic enzymes and IgG4 levels. Imaging revealed a short-segment MPD stenosis in the body of the pancreas without pancreatic swelling. Endoscopic ultrasonography showed localized periductal thickening of the MPD, raising suspicion of pancreatic carcinoma in situ (CIS). Cytological analysis of pancreatic juice identified atypical cells, prompting surgical resection. Histopathological examination of the resected specimen revealed characteristic features of type 1 AIP, including dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis, which were strictly confined to the subepithelial layer in the MPD. No malignant cells were found, and the surrounding pancreatic parenchyma showed only minimal fibrotic changes. This case may broaden the recognized clinical spectrum of AIP by demonstrating a rare presentation without mass formation or pancreatic swelling, which closely mimicked pancreatic CIS. Further accumulation of cases may enhance our comprehensive understanding of this disease entity.<\/jats:p>","DOI":"10.1007\/s12328-026-02315-2","type":"journal-article","created":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T09:30:54Z","timestamp":1774603854000},"page":"664-669","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Autoimmune pancreatitis limited to the main pancreatic duct without mass formation"],"prefix":"10.1007","volume":"19","author":[{"given":"Kaoruko","family":"Kanamaru","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1072-5243","authenticated-orcid":false,"given":"Arata","family":"Sakai","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takashi","family":"Kobayashi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Atsuhiro","family":"Masuda","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Norimitsu","family":"Uza","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takayuki","family":"Kodama","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoshihide","family":"Nanno","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takumi","family":"Fukumoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuzo","family":"Kodama","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,3,27]]},"reference":[{"key":"2315_CR1","doi-asserted-by":"crossref","first-page":"902","DOI":"10.2958\/suizo.33.902","volume":"33","author":"The Japan Pancreas Society; The Research Program on Intractable Diseases from the Ministry of Labor and Welfare of Japan","year":"2018","unstructured":"The Japan Pancreas Society; The Research Program on Intractable Diseases from the Ministry of Labor and Welfare of Japan. [Japanese clinical diagnostic criteria for autoimmune pancreatitis, 2018 (proposal)\u2014revision of Japanese clinical diagnostic criteria for autoimmune pancreatitis, 2011]. Suizo. 2018;33:902\u201313. (Japanese).","journal-title":"Suizo"},{"key":"2315_CR2","doi-asserted-by":"publisher","first-page":"345","DOI":"10.1148\/radiol.2332031436","volume":"233","author":"DV Sahani","year":"2004","unstructured":"Sahani DV, Kalva SP, Farrell J, et al. Autoimmune pancreatitis: imaging features. Radiology. 2004;233:345\u201352.","journal-title":"Radiology"},{"key":"2315_CR3","doi-asserted-by":"publisher","first-page":"555","DOI":"10.1007\/s10396-021-01144-9","volume":"48","author":"A Kanno","year":"2021","unstructured":"Kanno A, Tamada K, Fukushima N, et al. Endoscopic ultrasound-guided tissue acquisition for the histopathological diagnosis of autoimmune pancreatitis. J Med Ultrason. 2021;48:555\u201363.","journal-title":"J Med Ultrason"},{"key":"2315_CR4","doi-asserted-by":"crossref","first-page":"465","DOI":"10.2958\/suizo.35.465","volume":"35","author":"Japanese Study Group of Autoimmune Pancreatitis","year":"2020","unstructured":"Japanese Study Group of Autoimmune Pancreatitis. Ministry of Health, Labour and Welfare research team for Establishment of Diagnostic and Therapeutic Guidelines for IgG4-Related Disease. Clinical guidelines for autoimmune pancreatitis 2020. Suizo. 2020;35:465\u2013550. (Japanese).","journal-title":"Suizo"},{"key":"2315_CR5","doi-asserted-by":"publisher","first-page":"133","DOI":"10.1007\/s005350200009","volume":"37","author":"Y Koga","year":"2002","unstructured":"Koga Y, Yamaguchi K, Sugitani A, et al. Autoimmune pancreatitis starting as a localized form. J Gastroenterol. 2002;37:133\u20137.","journal-title":"J Gastroenterol"},{"key":"2315_CR6","doi-asserted-by":"publisher","first-page":"739","DOI":"10.2169\/internalmedicine.5754-20","volume":"60","author":"J Sato","year":"2020","unstructured":"Sato J, Matsubayashi H, Ishiwatari H, et al. Type 1 autoimmune pancreatitis extending along the main pancreatic duct: IgG4-related pancreatic periductitis. Intern Med. 2020;60:739\u201344.","journal-title":"Intern Med"},{"key":"2315_CR7","doi-asserted-by":"publisher","first-page":"61","DOI":"10.1016\/j.pan.2017.11.007","volume":"18","author":"A Kanno","year":"2018","unstructured":"Kanno A, Masamune A, Hanada K, et al. Multicenter study of early pancreatic cancer in Japan. Pancreatology. 2018;18:61\u20137.","journal-title":"Pancreatology"},{"key":"2315_CR8","doi-asserted-by":"publisher","first-page":"1133","DOI":"10.1007\/s00535-024-02149-0","volume":"59","author":"M Miki","year":"2024","unstructured":"Miki M, Masuda A, Takenaka M, et al. Association of pancreatic atrophy patterns with intraductal extension of early pancreatic ductal adenocarcinoma: a multicenter retrospective study. J Gastroenterol. 2024;59:1133\u201342.","journal-title":"J Gastroenterol"},{"key":"2315_CR9","doi-asserted-by":"publisher","first-page":"761","DOI":"10.1002\/ueg2.12557","volume":"12","author":"M Gonda","year":"2024","unstructured":"Gonda M, Masuda A, Kobayashi T, et al. Temporal progression of pancreatic cancer computed tomography findings until diagnosis: a large-scale multicenter study. United Eur Gastroenterol J. 2024;12:761\u201371.","journal-title":"United Eur Gastroenterol J"},{"key":"2315_CR10","doi-asserted-by":"publisher","first-page":"9","DOI":"10.1002\/jhbp.596","volume":"26","author":"T Kamisawa","year":"2019","unstructured":"Kamisawa T, Nakazawa T, Tazuma S, et al. Clinical practice guidelines for IgG4-related sclerosing cholangitis. J Hepatobiliary Pancreat Sci. 2019;26:9\u201342.","journal-title":"J Hepatobiliary Pancreat Sci"}],"container-title":["Clinical Journal of Gastroenterology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s12328-026-02315-2.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/article\/10.1007\/s12328-026-02315-2","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s12328-026-02315-2.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T10:22:47Z","timestamp":1779963767000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1007\/s12328-026-02315-2"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,27]]},"references-count":10,"journal-issue":{"issue":"3","published-print":{"date-parts":[[2026,6]]}},"alternative-id":["2315"],"URL":"https:\/\/doi.org\/10.1007\/s12328-026-02315-2","relation":{},"ISSN":["1865-7257","1865-7265"],"issn-type":[{"value":"1865-7257","type":"print"},{"value":"1865-7265","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,27]]},"assertion":[{"value":"18 December 2025","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"8 March 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"27 March 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The authors declare that they have no conflict of interest.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Conflict of interest"}}]}}