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Neurological manifestations may include meningeal, brainstem, and/or cerebellar involvement, where differential diagnoses extend to sarcoidosis, IgG4-related disease, autoimmune encephalitis, and high-risk syndromes. Neurological involvement can predict mortality and may be the sole presentation. The paper reviews updates in histiocytic disorders and complementary diagnostic strategies, emphasizing PET-CT to support biopsy planning and clinical interpretation. It also outlines how immunohistochemistry and BRAF V600E mutation testing can guide targeted therapy with vemurafenib.",{"@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/when-flames-hit-the-brain-and-the-spark-is-far-away-the-role-of-pet-ct-in-diagnosing-neurological-erdheim-chester-disease/435855/",{"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/when-flames-hit-the-brain-and-the-spark-is-far-away-the-role-of-pet-ct-in-diagnosing-neurological-erdheim-chester-disease/435855.png","ImageObject",300,407,{"name":92,"@type":93},"Logic","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-09-30","2026-09-29",true,{"@type":102,"interactionType":103,"userInteractionCount":14},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"Why is PET-CT important in diagnosing neurological Erdheim-Chester disease?","Question",{"text":112,"@type":113},"PET-CT helps identify systemic involvement and metabolic patterns that can support the diagnostic pathway, including selecting targets for biopsy in patients with neurological symptoms.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"Which differential diagnoses are considered when neurological ECD is suspected?",{"text":117,"@type":113},"Differential diagnoses mentioned include sarcoidosis, IgG4-related disorders, autoimmune encephalitis, and high-risk syndromes.",{"name":119,"@type":110,"acceptedAnswer":120},"How does BRAF V600E mutation testing affect treatment decisions?",{"text":121,"@type":113},"Detection of BRAF V600E mutation in biopsy tissue confirms ECD and supports eligibility for targeted therapy such as vemurafenib.","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},435855,1790793815,{"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":14,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":24,"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},1099513958762,"https://ap-avatar.wpscdn.com/avatar/1000023916a998db790?x-image-process=image/resize,m_fixed,w_180,h_180&k=1784791008015729253","Article published online: 2025-02-28  \nPractice Neurology 1  \nWhen flames hit the brain, and the spark is faraway: the role of PET-CT in diagnosing neurological Erdheim-Chester disease  \nCaio César Diniz Disserol 1,2,3 Guilherme Fleury Perini3 Flávia Fernandes Silva Zacchi4 Lívia Almeida Dutra3  \n1 Universidade Federal do Paraná, Hospital de Clínicas, Curitiba PR, Brazil.  \n2 Instituto de Neurologia de Curitiba, Curitiba PR, Brazil.  \n3 Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo SP, Brazil.  \n4 Grupo Fleury, Departamento de Anatomia Patológica, São Paulo SP, Brazil.  \nArq. Neuro-Psiquiatr. 2025;83(1):s00451802959 .  \nAddress for correspondence Lívia Almeida Dutra (email: [livia.dutra@einstein.br](livia.dutra@einstein.br))  \nAbstract  \nKeywords  \n► ErdheimChester Disease  \n► Histiocytosis  \n► Positron-Emission TomographyComputed Tomography  \n► Proto-Oncogene Proteins B-Raf  \nErdheim-Chester disease (ECD) is a rare histiocytic disorder that poses diagnostic and therapeutic challenges. Neurological manifestations are characterized by involvement of the meninges, brainstem, and/or cerebellum, and the differential diagnoses include sarcoidosis, IgG4 related disorders, autoimmune encephalitis, and high-risk syndromes. While present in a significant proportion of cases, neurological involvement is a predictor of mortality and may be the sole manifestation of the disease. In this paper, we discuss recent updates in histiocytic disorders and complementary diagnostic approaches, including positron-emission tomography-computed tomography (PETCT), as guidance for biopsy in patients with neurological symptoms. Additionally, we explore how clinicians can interpret biopsy findings in conjunction with immunohistochemistry to guide targeted therapies, such as vemurafenib, for BRAF V600E mutation.  \nTEACHING POINTS  \n1. Consider Erdheim-Chester disease (ECD) in patients presenting with neurological manifestations and bone lesions, even in cases suggestive of bone infarction.  \n2. Use positron-emission tomography-computed tomography (PET-CT) to investigate systemic involvement in patients with suspected neurological histiocytosis.  \n3. Request testing for BRAF V600E mutation in tissue biopsy samples to assess eligibility for targeted therapies, such as vemurafenib.  \nCLINICAL VIGNETTE  \nA 77-year-old male patient with a history of heavy smoking presented with progressive dizziness and imbalance in the 15 days prior to consultation. His symptoms progressed after a couple of days to include dysarthria and diplopia, prompting hospital admission for further evaluation. There were no cognitive complaints; however, he reported an 8 kg weight loss in the 5 months prior to hospital admission.  \nPhysical examination revealed an ataxic gait, ocular motor apraxia, normal extrinsic eye movements, normal muscle strength, brisk deep tendon reflexes, appendicular ataxia, and left hypoesthesia.  \nreceived  \nDecember 11, 2024 received in its final form January 12, 2025  \naccepted  \nJanuary 13, 2025  \nDOI [https://doi.org/](https://doi.org/)[ ](https://doi.org/)10.1055/s-0045-1802959 . ISSN 0004-282X  \nEditor-in-Chief: Hélio A. G. Teive.  \nAssociate Editor: Ayrton Roberto Massaro.  \n© 2025 . The Author(s) .  \nThis is an open access article published by Thieme under the terms of the Creative Commons Attribution 4.0 International License, permitting copying and reproduction so long as the original work is given appropriate credit ([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)).  \nThieme Revinter Publicações Ltda. , Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil  \n2 Role of PET-CT in Erdheim-Chester disease Disserol et al.  \nFigure 1 Brain magnetic resonance imaging showed a T2/fluidattenuated inversion recovery brainstem lesion at the dorsal pontomesencephalic junction (white arrows) with contrast enhancement (yellow arrows) .  \nBrain magnetic resonance imaging (MRI)re","cbCaioTB5VTqdorG","https://ap.wps.com/l/cbCaioTB5VTqdorG","pdf",1788283,"English","# Abstract\n## Teaching points\n## Clinical vignette\n## Imaging and laboratory findings\n## Biopsy and immunohistochemistry\n## Targeted therapy and outcome\n## From presentation to resolution: lessons learned","[{\"question\":\"Why is PET-CT important in diagnosing neurological Erdheim-Chester disease?\",\"answer\":\"PET-CT helps identify systemic involvement and metabolic patterns that can support the diagnostic pathway, including selecting targets for biopsy in patients with neurological symptoms.\"},{\"question\":\"Which differential diagnoses are considered when neurological ECD is suspected?\",\"answer\":\"Differential diagnoses mentioned include sarcoidosis, IgG4-related disorders, autoimmune encephalitis, and high-risk syndromes.\"},{\"question\":\"How does BRAF V600E mutation testing affect treatment decisions?\",\"answer\":\"Detection of BRAF V600E mutation in biopsy tissue confirms ECD and supports eligibility for targeted therapy such as vemurafenib.\"}]","When flames hit the brain, and the spark is far away - the role of PET-CT in diagnosing neurological Erdheim-Chester disease | PDF",1790675576,13]