{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T05:25:16Z","timestamp":1787117116279,"version":"build-2736575974"},"reference-count":32,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T00:00:00Z","timestamp":1787097600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:p>Extramammary Paget disease (EMPD) is a rare cutaneous adenocarcinoma that usually arises in apocrine gland-bearing areas, whereas primary ectopic EMPD of the abdominal skin is exceptionally uncommon. We report a 79-year-old woman with a five-year history of progressively enlarging eczema-like lower abdominal-pelvic skin lesions, including erosion, exudation, scaling, crusting, and pruritus, initially treated as chronic dermatitis without improvement. Histopathology showed large atypical Paget cells with focal dermal microinvasion; immunohistochemistry was positive for cytokeratin 7 (CK7) and GATA-binding protein 3\u00a0(GATA3) and negative for cytokeratin 20 (CK20) and p40, while Ki-67, a proliferation marker, showed a labeling index of approximately 60%. Because radical surgery was unsuitable, she received response-adapted two-stage electron beam radiotherapy. The first stage delivered 43.2 Gy in 12 every-other-day fractions using 12-MeV electrons, a 5-mm tissue-equivalent bolus, and customized lead shielding, followed by a 10 Gy boost in five daily fractions using 9-MeV electrons for residual visible disease. The treated field showed complete clinical resolution approximately one month after radiotherapy, with no in-field recurrence nearly one year later. Residual erythematous scaly plaques persisted outside the original field. This case supports response-adapted electron beam radiotherapy as a feasible non-surgical option for selected inoperable superficial EMPD and emphasizes the practical importance of pretreatment mapping, adequate field coverage, bolus conformity, shielding, and field-edge planning for extensive lesions on curved body surfaces.<\/jats:p>","DOI":"10.3389\/fonc.2026.1923850","type":"journal-article","created":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T04:39:07Z","timestamp":1787114347000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: staged electron beam radiotherapy for inoperable primary ectopic abdominal extramammary Paget disease"],"prefix":"10.3389","volume":"16","author":[{"given":"Jiarun","family":"Jiang","sequence":"first","affiliation":[{"name":"Department of Gastroenterology, Hubei Provincial Clinical Research Center for Intestinal and Colorectal Diseases, Hubei Key Laboratory of Intestinal and Colorectal Diseases, Zhongnan Hospital of Wuhan University","place":["Wuhan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunxu","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Radiation and Medical Oncology, Hubei Key Laboratory of Tumor Biological Behaviors, Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University","place":["Wuhan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qingming","family":"Xiang","sequence":"additional","affiliation":[{"name":"Department of Radiation and Medical Oncology, Hubei Key Laboratory of Tumor Biological Behaviors, Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University","place":["Wuhan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dazhen","family":"Jiang","sequence":"additional","affiliation":[{"name":"Department of Radiation and Medical Oncology, Hubei Key Laboratory of Tumor Biological 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