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A 53-year-old man developed a new left parasagittal extra-axial lesion with bony and subgaleal extension 11 months after maximal safe resection and chemoradiotherapy. Histology showed a high-grade sarcomatoid tumor with focal glial features mimicking secondary gliosarcoma, while molecular testing preserved key original variants and acquired a TP53 mutation. The report highlights clonal evolution and histological transformation considerations during atypical recurrences.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/distal-noncontiguous-recurrence-and-sarcomatous-transformation-of-glioblastoma-with-stable-molecular-profile-illustrative-case/440284/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/distal-noncontiguous-recurrence-and-sarcomatous-transformation-of-glioblastoma-with-stable-molecular-profile-illustrative-case/440284.png","ImageObject",300,407,{"name":92,"@type":93},"Blue Pony","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-31","2026-09-29",true,{"@type":102,"interactionType":103,"userInteractionCount":44},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What progression pattern does the case describe in glioblastoma?","Question",{"text":112,"@type":113},"The case describes distal noncontiguous extra-axial recurrence accompanied by sarcomatous transformation of glioblastoma.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"Which molecular findings were preserved and which new change was acquired?",{"text":117,"@type":113},"Key TERT, PIK3CA, and PTEN variants from the original glioblastoma were preserved, while a newly acquired TP53 mutation was detected in the transformed tumor.",{"name":119,"@type":110,"acceptedAnswer":120},"Why should clinicians consider histological transformation during atypical or extracranial recurrences?",{"text":121,"@type":113},"Because the transformed recurrence can mimic other entities, and molecular continuity with the primary tumor can clarify tumor biology and the recurrence pattern.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},440284,1790862946,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":44,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":34,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144,"preview_page_count":4},962090760266,"https://ap-avatar.wpscdn.com/davatar_276721f389ce27ea32af1340a28f341c","JOURNAL OF NEUROSURGERY:  \nCase Lessons  \nJ Neurosurg Case Lessons 11(1): CASE25714, 2026  \nDOI: 10.3171/CASE25714  \nDistal noncontiguous recurrence and sarcomatous transformation of glioblastoma with stable molecular profile: illustrative case  \nJacob Howran, BHSc,1 Kaytlin Andrews, BASc,2 Kana Ogawa, MSc,2 Douglas Cook, MD, PhD,1 ,3 James Purzner, MD, PhD,1 ,3 Fabio Ynoe Moraes, MD, PhD,1 ,4 John P. Rossiter, MBBCh, PhD,1 ,5 and Teresa Purzner, MD, PhD1 ,3  \n1School of Medicine and 2Department of Translational Medicine, Queen’s University, Kingston, Ontario, Canada; and 3Division of Neurosurgery, 4Division of Radiation Oncology, and 5Department of Pathology and Molecular Medicine, Kingston Health Sciences Centre, Kingston, Ontario, Canada  \nBACKGROUND Glioblastoma (GB) typically recurs locally and maintains a glial histopathological phenotype. Sarcomatoid transformation is rare, and distal extra-axial recurrence with bone and soft tissue involvement is exceptionally uncommon. Molecular features of such sarcomatoid transformations remain poorly described.  \nOBSERVATIONS The authors present the case of a 53-year-old man with a history of right temporal GB (IDH-wildtype, MGMT-unmethylated) treated with maximal safe resection and chemoradiotherapy. Eleven months postoperatively, surveillance MRI demonstrated local enhancement with a new left parasagittal extra-axial lesion with bony and subgaleal extension. Debulking and resection revealed a high-grade sarcomatoid tumor with focal glial immunophenotype, mimicking a secondary gliosarcoma but with near-complete predominance of the sarcomatous component. Molecular analysis demonstrated preservation of TERT, PIK3CA, and PTEN variants identified in the original GB, with acquisition of a TP53 mutation.  \nLESSONS This case illustrates a rare pattern of GB progression, characterized by distal extra-axial recurrence with sarcomatoid transformation. The shared driver TERT, PIK3CA, and PTEN mutations in the original right temporal and subsequent left extra-axial lesion support clonal evolution, while the newly acquired TP53 alteration may underlie histological shift. Clinicians should consider histological transformation when evaluating atypical or extracranial recurrences, as molecular continuity with the primary tumor can guide interpretation of tumor biology and recurrence patterns.  \n[https://thejns.org/doi/abs/10.3171/CASE25714](https://thejns.org/doi/abs/10.3171/CASE25714)  \nKEYWORDS glioblastoma; gliosarcoma; distal recurrence; transformation; case report  \nGlioblastoma (GB) is the most aggressive primary brain tumor in adults, with a median survival of approximately 15 months despite maximal safe resection and chemoradiotherapy.1 Recurrence is nearly universal and, in most cases (approximately 80%), arises at or near the resection margin.2 Distant intracranial or extracranial metastases are exceedingly rare, reported in only 0 .2%–1 .2% of cases. The majority of recurrent GBs retain the molecular profile of the primary tumor.3 Gliosarcoma (GS), a rare glial-sarcomatous variant of GB comprising 1%–2% of cases,4 may occur de novo or secondarily following treatment of GB, often after radiotherapy.5–8 The timeline of secondary GS development is variable, but the median time to progression from first diagnosis of GB is approximately 11–14 months and from irradiation (mean 55 Gy) 44.8 weeks, and the median survival after diagnosis of secondary GS is approximately 6 months.7,9, 10 Secondary GS typically demonstrates overlapping molecular features with GB but distinct biphasic morphology.5,6 Compared to GB, GS has a higher propensity  \nfor extra-axial, dural, and osseous spread.10, 11 Importantly, both glialand sarcomatous components of GS are thought to arise from a single clonal precursor, wherein the mutational burden and molecular profiles within the same tumor are generally preserved.12 To our knowledge, distal extra-axial recurrence with sarcomatoid transformation, accompanied by pre","cbCaigWvkT4Rz8VQ","https://ap.wps.com/l/cbCaigWvkT4Rz8VQ","pdf",6153319,"English","# Case Lessons\n## Background\n## Observations\n## Lessons\n## Illustrative Case\n## Clinical Course","[{\"question\":\"What progression pattern does the case describe in glioblastoma?\",\"answer\":\"The case describes distal noncontiguous extra-axial recurrence accompanied by sarcomatous transformation of glioblastoma.\"},{\"question\":\"Which molecular findings were preserved and which new change was acquired?\",\"answer\":\"Key TERT, PIK3CA, and PTEN variants from the original glioblastoma were preserved, while a newly acquired TP53 mutation was detected in the transformed tumor.\"},{\"question\":\"Why should clinicians consider histological transformation during atypical or extracranial recurrences?\",\"answer\":\"Because the transformed recurrence can mimic other entities, and molecular continuity with the primary tumor can clarify tumor biology and the recurrence pattern.\"}]","Distal noncontiguous recurrence and sarcomatous transformation of glioblastoma with stable molecular profile - illustrative case | PDF",1790691714,18]