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Dysembryoplastic neuroepithelial tumor — Clinical Guidelines

Overview

Dysembryoplastic neuroepithelial tumor (DNET) is a benign, slow-growing glioneuronal tumor predominantly found in children and young adults, often associated with chronic, drug-resistant epilepsy. Clinically, DNETs are characterized by their cortical location and propensity to cause seizures without significant tumor progression for extended periods. These tumors were initially considered benign and static, but recent studies highlight their potential for recurrence and, rarely, progression to more aggressive forms. Understanding DNET is crucial in day-to-day practice for accurate diagnosis, appropriate surgical intervention, and long-term management to prevent seizure recurrence and tumor relapse 1 3 13.

Pathophysiology

The pathophysiology of DNETs involves complex interactions at molecular and cellular levels, primarily centered around genetic alterations that activate signaling pathways critical for tumor growth and epileptogenesis. A hallmark genetic alteration in DNETs is the activation of the RAS/MAPK pathway, often mediated through FGFR1 mutations, including intragenic duplications and fusion transcripts like FGFR1-TACC1 1 3 10. These genetic changes lead to dysregulated cell proliferation and neuronal-glial interactions, contributing to the characteristic multinodular architecture and epileptogenic properties of DNETs. The presence of specific glioneuronal elements, such as oligodendroglial-like cells and "floating neurons," further underscores the unique biology of these tumors. Additionally, the association with focal cortical dysplasia in many cases suggests a developmental origin intertwined with genetic predispositions 1 3 11.

Epidemiology

DNETs predominantly affect children and young adults, with an incidence ranging from 5% to 20% of all pediatric low-grade gliomas 1 3. These tumors are more frequently encountered in the temporal lobes, though they can occur in other cortical regions. There is no significant sex predilection noted in most studies, and geographic distribution appears to be consistent across different populations without marked regional variations. Over time, there has been an increasing recognition of DNETs due to advancements in neuroimaging and surgical techniques, leading to higher diagnostic rates 1 3 13.

Clinical Presentation

Patients with DNET typically present with early-onset, intractable focal epilepsy, often manifesting in childhood or adolescence. Seizures are frequently resistant to medical management, necessitating surgical evaluation. Neuroimaging often reveals characteristic features such as a bubbly, popcorn-like appearance or well-demarcated mass lesions with potential satellite nodules in the subcortical white matter. Atypical presentations may include atypical locations outside the cortex, such as the cerebellum or caudate nucleus, and unusual imaging features like contrast enhancement or calcification, which can complicate diagnosis 1 5 15 18.

Diagnosis

The diagnosis of DNET involves a combination of clinical evaluation, neuroimaging, and histopathological analysis. Key diagnostic criteria include:

Clinical Presentation: Early-onset, drug-resistant focal epilepsy.

Imaging: MRI showing characteristic cortical lesions with a bubbly or multinodular appearance, possibly with satellite lesions.

Histopathology: Identification of the specific glioneuronal element, including oligodendroglial-like cells and floating neurons.

Molecular Testing: Detection of FGFR1 alterations, such as duplications or fusion transcripts, via techniques like droplet digital PCR on FFPE tissue.

Required Tests:

MRI: High-resolution T1, T2, FLAIR sequences.

Biopsy/Resection: Histopathological examination with immunohistochemistry for specific markers.

Molecular Analysis: Droplet digital PCR for FGFR1 alterations.

Differential Diagnosis:

Focal Cortical Dysplasia: Lacks the glioneuronal element but shares epileptogenic properties.

Ganglioglioma: Typically shows more distinct neuronal and glial components without the specific glioneuronal architecture.

Pilocytic Astrocytoma: Usually more uniformly astrocytic without the characteristic DNET features.

Diffuse Astrocytoma: May present similarly but lacks the specific histopathological markers of DNET 1 3 11.

Management

Surgical Intervention

Primary Approach: Gross total resection is recommended to minimize seizure recurrence and tumor progression.

Considerations: Careful delineation of tumor borders, including satellite lesions, to ensure complete removal.

Post-Surgical Monitoring: Regular MRI follow-up to assess for recurrence.

Medical Management

Seizure Control: Antiepileptic drugs (AEDs) as initial management; consider second-line AEDs if partial response.

Adjunctive Therapy: Radiation therapy or chemotherapy reserved for recurrent or progressive cases, though rare 9 14.

Specific Treatments:

Antiepileptic Drugs: Phenobarbital, valproate, levetiracetam (dose individualized based on response and side effects).

Radiation Therapy: Considered in cases of recurrence or malignant transformation (e.g., temozolomide concurrent with radiation).

Complications

Seizure Recurrence: Common post-surgery, necessitating continued AED therapy.

Tumor Recurrence: Satellite lesions or main tumor recurrence may require reoperation.

Neuropsychological Impact: Cognitive and behavioral changes post-surgery, particularly in pediatric patients.

Referral Triggers: Persistent seizures post-surgery, imaging evidence of recurrence, or neurological decline 1 13 14.

Prognosis & Follow-Up

The prognosis for DNET is generally favorable, with many patients achieving seizure freedom post-surgery. However, recurrence rates can be significant, particularly if satellite lesions are not fully resected. Key prognostic indicators include complete resection and absence of molecular alterations predictive of aggressive behavior. Recommended follow-up intervals include:

Imaging: MRI every 6-12 months for the first few years post-surgery, then annually if stable.

Clinical Monitoring: Regular neurological assessments to detect early signs of recurrence or complications.

Special Populations

Pediatrics

Considerations: Developmental impact of surgery, tailored AED regimens, and close follow-up due to higher recurrence rates.

Management: Multidisciplinary approach involving neurologists, neurosurgeons, and pediatricians.

Elderly

Rarity: DNETs are uncommon in elderly populations, but when present, management focuses on minimizing surgical risks and optimizing seizure control.

Approach: Conservative surgical strategies and careful AED titration due to comorbidities.

Key Recommendations

Surgical Resection: Gross total resection is recommended to reduce seizure recurrence and tumor progression (Evidence: Strong 1 3).

Molecular Testing: Incorporate FGFR1 alteration testing via droplet digital PCR in diagnostic workup (Evidence: Moderate 3 10).

Long-Term Follow-Up: Schedule regular MRI and clinical assessments post-surgery to monitor for recurrence (Evidence: Moderate 1 13).

Comprehensive Imaging: Utilize high-resolution MRI sequences to identify characteristic features and satellite lesions (Evidence: Moderate 1 5).

Multidisciplinary Care: Engage neurologists, neurosurgeons, and pediatric specialists for pediatric cases to optimize outcomes (Evidence: Expert opinion 1).

Seizure Management: Initiate and adjust antiepileptic drugs based on individual response and side effect profiles (Evidence: Moderate 1 3).

Consider Adjunctive Therapy: Evaluate radiation therapy or chemotherapy for recurrent or aggressive cases, though these are rare (Evidence: Weak 9 14).

Monitor for Recurrence: Be vigilant for imaging signs of recurrence and clinical seizure relapse post-surgery (Evidence: Moderate 1 13).

Genetic Counseling: Offer genetic counseling for familial cases or suspected genetic predispositions (Evidence: Expert opinion 4).

Neuropsychological Support: Provide psychological support and cognitive assessments, especially in pediatric patients (Evidence: Expert opinion 1).

References

1 Lee Y, Yang J, Choi SA, Kim SK, Park SH, Park HJ et al.. Genomic analysis as a tool to infer disparate phylogenetic origins of dysembryoplastic neuroepithelial tumors and their satellite lesions. Scientific reports 2023. link 2 Pagès M, Debily MA, Fina F, Jones DTW, Saffroy R, Castel D et al.. The genomic landscape of dysembryoplastic neuroepithelial tumours and a comprehensive analysis of recurrent cases. Neuropathology and applied neurobiology 2022. link 3 Fina F, Barets D, Colin C, Bouvier C, Padovani L, Nanni-Metellus I et al.. Droplet digital PCR is a powerful technique to demonstrate frequent FGFR1 duplication in dysembryoplastic neuroepithelial tumors. Oncotarget 2017. link 4 Rivera B, Gayden T, Carrot-Zhang J, Nadaf J, Boshari T, Faury D et al.. Germline and somatic FGFR1 abnormalities in dysembryoplastic neuroepithelial tumors. Acta neuropathologica 2016. link 5 Kushel YV, Kutin MA, Ivanov VV, Chernov IV, Adueva DS, Pronin IN et al.. Disseminated ependymal dysembryoplastic neuroepithelial tumor: a case report and literature review. Zhurnal voprosy neirokhirurgii imeni N. N. Burdenko 2024. link 6 Kim JW, Kang YK, Paeng JC, Kim SK, Lim BC, Kim KJ et al.. Diverse Patterns and Clinical Significance of 11C-Methionine PET in Dysembryoplastic Neuroepithelial Tumors. Clinical nuclear medicine 2022. link 7 Ishi Y, Shimizu A, Takakuwa E, Sugiyama M, Okamoto M, Motegi H et al.. High-grade neuroepithelial tumor with BCL6 corepressor-alteration presenting pathological and radiological calcification: A case report. Pathology international 2021. link 8 Onishi S, Amatya VJ, Kolakshyapati M, Takano M, Yonezawa U, Taguchi A et al.. T2-FLAIR mismatch sign in dysembryoplasticneuroepithelial tumor. European journal of radiology 2020. link 9 Morr S, Qiu J, Prasad D, Mechtler LL, Fenstermaker RA. Radiologic response to radiation therapy concurrent with temozolomide for progressive simple dysembryoplastic neuroepithelial tumor. Acta neurochirurgica 2016. link 10 Matyja E, Grajkowska W, Kunert P, Marchel A. A peculiar histopathological form of dysembryoplastic neuroepithelial tumor with separated pilocytic astrocytoma and rosette-forming glioneuronal tumor components. Neuropathology : official journal of the Japanese Society of Neuropathology 2014. link 11 Komori T, Arai N. Dysembryoplastic neuroepithelial tumor, a pure glial tumor? Immunohistochemical and morphometric studies. Neuropathology : official journal of the Japanese Society of Neuropathology 2013. link 12 Mano Y, Kumabe T, Shibahara I, Saito R, Sonoda Y, Watanabe M et al.. Dynamic changes in magnetic resonance imaging appearance of dysembryoplastic neuroepithelial tumor with or without malignant transformation. Journal of neurosurgery. Pediatrics 2013. link 13 Daghistani R, Miller E, Kulkarni AV, Widjaja E. Atypical characteristics and behavior of dysembryoplastic neuroepithelial tumors. Neuroradiology 2013. link 14 Ray WZ, Blackburn SL, Casavilca-Zambrano S, Barrionuevo C, Orrego JE, Heinicke H et al.. Clinicopathologic features of recurrent dysembryoplastic neuroepithelial tumor and rare malignant transformation: a report of 5 cases and review of the literature. Journal of neuro-oncology 2009. link 15 Tailor JK, Kim AH, Folkerth RD, Black PM. The development of ring-shaped contrast enhancement in a case of cerebellar dysembryoplastic neuroepithelial tumor: case report. Neurosurgery 2008. link 16 Saito T, Sugiyama K, Yamasaki F, Tominaga A, Kurisu K, Takeshima Y et al.. Familial occurrence of dysembryoplastic neuroepithelial tumor-like neoplasm of the septum pellucidum: case report. Neurosurgery 2008. link 17 Maher CO, White JB, Scheithauer BW, Raffel C. Recurrence of dysembryoplastic neuroepithelial tumor following resection. Pediatric neurosurgery 2008. link 18 Wang F, Qiao G, Li X, Gui Q. A dysembryoplastic neuroepithelial tumor in the area of the caudate nucleus in a 57-year-old woman: case report. Neurosurgery 2007. link 19 Parmar HA, Hawkins C, Ozelame R, Chuang S, Rutka J, Blaser S. Fluid-attenuated inversion recovery ring sign as a marker of dysembryoplastic neuroepithelial tumors. Journal of computer assisted tomography 2007. link 20 Jensen RL, Caamano E, Jensen EM, Couldwell WT. Development of contrast enhancement after long-term observation of a dysembryoplastic neuroepithelial tumor. Journal of neuro-oncology 2006. link 21 Duggal N, Iskander S, Hammond RR. MAP2 and nestin co-expression in dysembryoplastic neuroepithelial tumors. Clinical neuropathology 2003. link 22 Adamek D, Korzeniowska A, Morga R, Lopatka P, Jeleńska-Szyguła I, Danilewicz B. Dysembryoplastic neuroepithelial tumour (DNT). Is the mechanism of seizures related to glutamate? An immunohistochemical study. Folia neuropathologica 2001. link 23 Gyure KA, Sandberg GD, Prayson RA, Morrison AL, Armstrong RC, Wong K. Dysembryoplastic neuroepithelial tumor: an immunohistochemical study with myelin oligodendrocyte glycoprotein. Archives of pathology & laboratory medicine 2000. link 24 Taratuto AL, Pomata H, Sevlever G, Gallo G, Monges J. Dysembryoplastic neuroepithelial tumor: morphological, immunocytochemical, and deoxyribonucleic acid analyses in a pediatric series. Neurosurgery 1995. link

Dysembryoplastic neuroepithelial tumor