When flames hit the brain, and the spark is far away - the role of PET-CT in diagnosing neurological Erdheim-Chester disease

Sep 29, 2026

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Erdheim-Chester disease (ECD) is a rare histiocytic disorder that creates diagnostic and therapeutic challenges, particularly when neurological structures are involved. 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.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages5

Reading Time13 min

AccessFree to download

Abstract

Teaching points

Clinical vignette

Imaging and laboratory findings

Biopsy and immunohistochemistry

Targeted therapy and outcome

From presentation to resolution: lessons learned

Article published online: 2025-02-28 Practice Neurology 1 When ﬂames hit the brain, and the spark is faraway: the role of PET-CT in diagnosing neurological Erdheim-Chester disease Caio César Diniz Disserol 1,2,3 Guilherme Fleury Perini3 Flávia Fernandes Silva Zacchi4 Lívia Almeida Dutra3 1 Universidade Federal do Paraná, Hospital de Clínicas, Curitiba PR, Brazil. 2 Instituto de Neurologia de Curitiba, Curitiba PR, Brazil. 3 Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo SP, Brazil. 4 Grupo Fleury, Departamento de Anatomia Patológica, São Paulo SP, Brazil. Arq. Neuro-Psiquiatr. 2025;83(1):s00451802959 . Address for correspondence Lívia Almeida Dutra (email: [livia.dutra@einstein.br](livia.dutra@einstein.br)) Abstract Keywords ► ErdheimChester Disease ► Histiocytosis ► Positron-Emission TomographyComputed Tomography ► Proto-Oncogene Proteins B-Raf Erdheim-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. TEACHING POINTS 1. Consider Erdheim-Chester disease (ECD) in patients presenting with neurological manifestations and bone lesions, even in cases suggestive of bone infarction. 2. Use positron-emission tomography-computed tomography (PET-CT) to investigate systemic involvement in patients with suspected neurological histiocytosis. 3. Request testing for BRAF V600E mutation in tissue biopsy samples to assess eligibility for targeted therapies, such as vemurafenib. CLINICAL VIGNETTE A 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. Physical examination revealed an ataxic gait, ocular motor apraxia, normal extrinsic eye movements, normal muscle strength, brisk deep tendon reﬂexes, appendicular ataxia, and left hypoesthesia. received December 11, 2024 received in its ﬁnal form January 12, 2025 accepted January 13, 2025 DOI [https://doi.org/](https://doi.org/)[ ](https://doi.org/)10.1055/s-0045-1802959 . ISSN 0004-282X Editor-in-Chief: Hélio A. G. Teive. Associate Editor: Ayrton Roberto Massaro. © 2025 . The Author(s) . This 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/)). Thieme Revinter Publicações Ltda. , Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil 2 Role of PET-CT in Erdheim-Chester disease Disserol et al. Figure 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) . Brain magnetic resonance imaging (MRI)re

FAQs

Why is PET-CT important in diagnosing neurological Erdheim-Chester disease?

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.

Which differential diagnoses are considered when neurological ECD is suspected?

Differential diagnoses mentioned include sarcoidosis, IgG4-related disorders, autoimmune encephalitis, and high-risk syndromes.

How does BRAF V600E mutation testing affect treatment decisions?

Detection of BRAF V600E mutation in biopsy tissue confirms ECD and supports eligibility for targeted therapy such as vemurafenib.

Sep 29, 2026

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