{"paper_id":"4322b232-1f8c-4513-a4a0-1c4b2fcaebdc","body_text":"Abstract\nMalignant transformation of adenomyosis is rare, with endometrioid carcinoma being the most common histological type. Herein, we report the first extremely aggressive case of undifferentiated carcinoma arising from adenomyosis. A 59-year-old Japanese woman was referred to our hospital with complaints of general fatigue, abdominal fullness, and loss of appetite. Contrast-enhanced computed tomography (CT) and integrated whole-body positron emission tomography/CT using 18F-fluorodeoxyglucose revealed multiple para-aortic and pelvic lymph node swellings. Contrast-enhanced magnetic resonance imaging revealed a 3-cm degenerated intramural uterine tumor. The patient underwent total hysterectomy, bilateral salpingo-oophorectomy, para-aortic and pelvic lymphadenectomy, and partial omentectomy for the treatment. Pathologically, the patient was diagnosed with undifferentiated carcinoma arising from adenomyosis. Despite adjuvant chemotherapy, the patient died of the disease 7 months after the initial surgery. Further investigation of similar cases may reveal the clinical features of this disease.\nSimilar content being viewed by others\nData availability\nThe data are available on the request to the corresponding author.\nReferences\nBulun SE, Yildiz S, Adli M, Wei JJ (2021) Adenomyosis pathogenesis: insights from next-generation sequencing. Hum Reprod Update 27:1086–1097. https://doi.org/10.1093/humupd/dmab017\nKoike N, Tsunemi T, Uekuri C, Akasaka J, Ito F, Shigemitsu A et al (2013) Pathogenesis and malignant transformation of adenomyosis (review). Oncol Rep 29:861–867. https://doi.org/10.3892/or.2012.2184\nWang J, Wang Q, Wang W, Yang J, Xia J, Wei Y (2023) Endometrioid adenocarcinoma arising in adenomyosis in a patient with pelvic organ prolapse-case report. 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Radiographics 19:S147–S160. https://doi.org/10.1148/radiographics.19.suppl_1.g99oc13s147\nManfredi R, Mirk P, Maresca G, Margariti PA, Testa A, Zannoni GF et al (2004) Local-regional staging of endometrial carcinoma: role of MR imaging in surgical planning. Radiology 231:372–378. https://doi.org/10.1148/radiol.2312021184\nAcknowledgements\nWe would like to thank Editage (www.editage.jp) for English language editing.\nAuthor information\nAuthors and Affiliations\nCorresponding author\nEthics declarations\nConflict of interest\nNone declared.\nAdditional information\nPublisher’s note\nSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.\nAbout this article\nCite this article\nAoyagi, Y., Nasu, K., Nishida, H. et al. A case of undifferentiated carcinoma arising from adenomyosis. Int Canc Conf J (2026). https://doi.org/10.1007/s13691-026-00874-2\nReceived:\nAccepted:\nPublished:\nVersion of record:\nDOI: https://doi.org/10.1007/s13691-026-00874-2","source_license":"CC0","license_restricted":false}