{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T14:38:50Z","timestamp":1786113530842,"version":"build-2736575974"},"reference-count":35,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2026,5,26]],"date-time":"2026-05-26T00:00:00Z","timestamp":1779753600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,5,26]],"date-time":"2026-05-26T00:00:00Z","timestamp":1779753600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Histopathology"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:sec>\n                    <jats:title>Aims<\/jats:title>\n                    <jats:p>We identified three extra\u2010appendiceal low\u2010grade appendiceal mucinous neoplasms (LAMN)\u2010like lesions occurring in the absence of appendiceal involvement, raising uncertainty regarding their classification, biologic nature, and clinical significance.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We identified three cases of LAMN\u2010like lesions arising in duplication cysts, anatomically separate from the appendix. These cases were evaluated by detailed histologic and immunohistochemical analysis and compared with other gastrointestinal duplication cysts diagnosed at the same institution. Whole\u2010exome sequencing was performed in all three LAMN\u2010like cases.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      All three lesions demonstrated defining histologic features of LAMN, including low\u2010grade mucinous epithelium with apical mucin, abundant luminal mucin, undulating or papillary architecture, obliteration of the lamina propria, effacement of the muscularis mucosae and mural fibrosis. Features of a background duplication cyst were at least focally present, and appendiceal involvement was absent in\u00a0all cases. The epithelium showed an intestinal immunophenotype with strong CK20 and CDX2 expression and absent or minimal CK7 staining. Molecular analysis revealed activating\n                      <jats:italic>KRAS<\/jats:italic>\n                      or\n                      <jats:italic>GNAS<\/jats:italic>\n                      mutations in all three cases, including one case with co\u2010occurring mutations, mirroring the molecular profile of conventional appendiceal LAMN.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>We describe extra\u2010appendiceal LAMN\u2010like lesions that recapitulate the morphologic, immunophenotypic, and molecular features of appendiceal LAMN despite the absence of appendiceal involvement. These findings support the interpretation of these lesions as true neoplastic proliferations arising within non\u2013lumen\u2010communicating cystic epithelial compartments, such as duplication cysts. Recognition of this rare phenomenon is critical to avoid misclassification and may have implications for staging, surveillance, and clinical management analogous to appendiceal LAMN.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/his.70183","type":"journal-article","created":{"date-parts":[[2026,5,26]],"date-time":"2026-05-26T10:44:41Z","timestamp":1779792281000},"page":"512-521","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Extra\u2010appendiceal low\u2010grade mucinous neoplasm\u2010like lesions: clinicopathologic and molecular characteristics"],"prefix":"10.1111","volume":"89","author":[{"given":"Soo Hyun","family":"Lee","sequence":"first","affiliation":[{"name":"Department of Pathology Beth Israel Deaconess Medical Center  Boston Massachusetts USA"},{"name":"Harvard Medical School  Boston Massachusetts 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