{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,21]],"date-time":"2026-06-21T20:49:03Z","timestamp":1782074943948,"version":"3.54.5"},"reference-count":10,"publisher":"SAGE Publications","license":[{"start":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T00:00:00Z","timestamp":1781654400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Pediatr Dev Pathol"],"abstract":"<jats:p>Fetiform teratoma (FT) and fetus-in-fetu (FIF) represent a spectrum of rare retroperitoneal masses containing organoid structures. While FIF is classically defined by the presence of a vertebral axis, FT lacks this organized skeletal development. Distinguishing between these entities is critical given the malignant potential associated with FT, estimated at approximately 10%. We report a case of a 5-month-old male presenting with a large (12\u2009cm) retroperitoneal mass and elevated alpha-fetoprotein (AFP 56.8\u2009IU\/mL; age-matched reference &lt;7\u2009IU\/mL). Macroscopically, the resected tumor featured a distinct rudimentary digitiform projection with a nail bed. Histopathology demonstrated extensive organoid differentiation, including gastrointestinal loops with muscular layers, respiratory epithelium, and well-formed pancreatic parenchyma and adrenal cortex. Despite the complex organogenesis and limb-like morphology, the absence of a vertebral column or ossified long bones supported a diagnosis of mature cystic teratoma with fetiform features (FT) over FIF. This report highlights the diagnostic ambiguity within the \u201cgray zone\u201d of these lesions and emphasizes the role of axial skeletal organization and serum AFP levels as complementary tools for classification and oncologic surveillance.<\/jats:p>","DOI":"10.1177\/10935266261457324","type":"journal-article","created":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T06:06:40Z","timestamp":1781762800000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":0,"title":["Fetiform Teratoma With a Digitiform Projection and Complex Organoid Differentiation (Adrenal and Pancreatic)"],"prefix":"10.1177","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5817-0067","authenticated-orcid":false,"given":"Svetlana","family":"Shalygina","sequence":"first","affiliation":[{"name":"Department of Anatomical Pathology, Hospital General Universitario Dr. Balmis, Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0781-3392","authenticated-orcid":false,"given":"Leticia","family":"Gracia S\u00e1enz","sequence":"additional","affiliation":[{"name":"Department of Anatomical Pathology, Hospital General Universitario Dr. Balmis, Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0416-8674","authenticated-orcid":false,"given":"Jer\u00f3nimo","family":"Gonz\u00e1lvez Pi\u00f1era","sequence":"additional","affiliation":[{"name":"Department of Pediatric Surgery, Hospital General Universitario Dr. Balmis, Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2039-5727","authenticated-orcid":false,"given":"Diana Patricia","family":"Ca\u00f1\u00f3n Murillo","sequence":"additional","affiliation":[{"name":"Department of Radiology, Hospital General Universitario Dr. Balmis, Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6927-6270","authenticated-orcid":false,"given":"Francisca Mar\u00eda","family":"Peir\u00f3 Marqu\u00e9s","sequence":"additional","affiliation":[{"name":"Department of Anatomical Pathology, Hospital General Universitario Dr. Balmis, Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2899-2908","authenticated-orcid":false,"given":"Gloria","family":"Peir\u00f3 Cabrera","sequence":"additional","affiliation":[{"name":"Department of Anatomical Pathology, Hospital General Universitario Dr. Balmis, Alicante, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2026,6,17]]},"reference":[{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1002\/path.1700400102"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00383-025-06087-7"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1080\/15513815.2025.2585373"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.7759\/cureus.33725"},{"key":"e_1_3_3_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.radcr.2023.12.031"},{"key":"e_1_3_3_7_2","doi-asserted-by":"publisher","DOI":"10.1055\/a-2206-4825"},{"key":"e_1_3_3_8_2","doi-asserted-by":"publisher","DOI":"10.1542\/peds.105.6.1335"},{"key":"e_1_3_3_9_2","doi-asserted-by":"publisher","DOI":"10.1002\/ccr3.70029"},{"key":"e_1_3_3_10_2","doi-asserted-by":"publisher","DOI":"10.1097\/SCS.0000000000012057"},{"key":"e_1_3_3_11_2","doi-asserted-by":"publisher","DOI":"10.1002\/ajmg.a.31362"}],"container-title":["Pediatric and Developmental Pathology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/10935266261457324","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/full-xml\/10.1177\/10935266261457324","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/10935266261457324","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,21]],"date-time":"2026-06-21T20:26:26Z","timestamp":1782073586000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1177\/10935266261457324"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,17]]},"references-count":10,"alternative-id":["10.1177\/10935266261457324"],"URL":"https:\/\/doi.org\/10.1177\/10935266261457324","relation":{},"ISSN":["1093-5266","1615-5742"],"issn-type":[{"value":"1093-5266","type":"print"},{"value":"1615-5742","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,17]]},"article-number":"10935266261457324"}}