|CASE IN POINT - CLINICS IN NEUROPATHOLOGY
|Year : 2016 | Volume
| Issue : 1 | Page : 58-60
Dysembryoplastic neuroepithelial tumor: A report of two cases
Varsha Dalal1, Manveen Kaur1, Karam Chand Sharma2, Avninder Singh1
1 Department of Pathology, National Institute of Pathology, ICMR, New Delhi, India
2 Department of Neurosurgery, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi, India
|Date of Web Publication||20-Oct-2016|
National Institute of Pathology, ICMR, Safdarjung Hospital Campus, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
The dysembryoplasticneuroepithelial tumor (DNT) is an uncommon lesion characterized by a mixedpopulation of neurons, astrocytes, and oligodendroglia-like cells. It is important to be aware of this entity because it can mimic an oligodendroglioma orneurocytoma which needs more aggressive therapeutic interventions. We present two cases of DNT with unusual radiologic findings and discuss the literature review.
Keywords: Dysembryoplastic neuroepithelial tumor, oligodendroglia, seizure
|How to cite this article:|
Dalal V, Kaur M, Sharma KC, Singh A. Dysembryoplastic neuroepithelial tumor: A report of two cases. Astrocyte 2016;3:58-60
| Introduction|| |
Dysembryoplasticneuroepithelial tumor (DNT) is a recently reported, benign, usually supratentorialglioneuronal neoplasmcharacterized by a predominantly cortical location and by drug-resistant partial seizures. The WHO classification categorizes it as a neuronal and mixed neuronal-glial tumor (Grade 1). It is usually seen in children and young adults.,, Clinical, radiological, and histopathological findings have to be considered inthe diagnosis these rare tumors and to differentiate it from its mimics and hence, to avoid aggressive therapy.
| Case Report|| |
A 10-year-old male presented with a 6-month history of multiple episodes of sudden-onset seizures. The parents also gave a history of head injury due to fall from height 3months back. There was no association with loss of consciousness or vomiting. Computed tomography (CT) scan of the brain revealed an intracranial space occupying lesion measuring 7.6 × 5.8 × 5.0 cmwith both solid and cystic components in the right paraventricular and parietal region, causing midline shift of septum pellucidum toward the left [Figure 1]a. The imaging features were suggestive of a malignant neoplasm with the possibilities of supratentorialprimitive neuroectodermal tumor, ependymoma, or rarely an atypical teratoid-rhabdoid tumor.
|Figure 1: (a) Sagittal view of computed tomography scan showing heterogeneously enhancing tumor, (b) vacuolated oligodendroglia-like tumor cells and admixed neurons.|
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Histopathologic examination of the tumor revealed uniform appearing oligodendroglia-like cells (OLCs) with vacuolated cytoplasm in a myxoid background. Also seen were specific glioneuronalelements comprising columns formed of axons lined by OLCswith intervening neurons floating in mucin pools [Figure 1]b. Based on these features, a diagnosis of DNT was rendered. The patient presented for follow-up 6months later and is asymptomatic.
A 13-year-old female presented with a 1-year history of seizures. There was no history of any head injury or trauma. Her Glasgow Coma Scale score was 15 (E4V5M6). Magnetic resonance (MR) T2- and T1-weighted images showed well-defined, superficial cortical-based cystic focal lesion in the left temporoparietal region, following fluid signal intensity with the absence of mass effect or perilesional edema [Figure 2]a. Craniotomywas performed, and the excised mass was sent forhistopathologic examination. The histomorphologicalfeatures led to the diagnosis of DNT [Figure 2]b. The patient is on follow-up and is asymptomatic.
|Figure 2: (a) Magnetic resonance imaging showing cortical based cystic lesion with absent mass effect, (b) tumor cells showing vacuolated cells with bubbly appearance.|
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| Discussion|| |
First described in 1988 by Daumas-Duport et al., DNTs are benign lesions affecting children and young adults and are clinically characterized by intractable seizures with or without symptoms of raised intracranial pressure. They usually do not show a neurological deficit. Four clinical features are characteristic of the disease process: long-standing partial complex seizures with early age of onset, no neurological deficit, normal intelligence, and no stigmata of phacomatosis.,, It has been suggested that glutaminergic system of neuro transmission may play a role in epileptogenesis in this lesion. The positivity of glutamate receptor 2 in the neurons dispersed within the tumor and reduced expression of excitatory aminoacid transporter proteins demonstrates the excitotoxic damage to neurons seen in DNT's.,
DNTs are usually located in the supratentorialcortex, with a predilection for the temporal lobe. These lesions are typically hypointense on T1-weighted and hyperintense on T2-weighted MR images. Edema and mass effect on midline structures are characteristically lacking., About one-third of DNTs show contrast enhancement, which often appears as multiple rings rather than homogeneous enhancement. These changes are seen usually due to is chemic and/or hemorrhagic changes. The cystic appearance on MR images is also a feature of DNT despite the absence of true cysts intraoperatively or on microscopic examination.
Daumas-Duportet al.proposed these lesions to be neoplastic as they may form a sizable mass and exhibit increases cellularity with occasional pleomorphism and high MIB-1 labeling index. Evidence supporting a hamartomatous process includes the lesion's frequent association with cortical dysplasia, heterogeneous composition, and its apparent cure by surgical excision. Histopathologic hallmarks are bundles of axons lined by OLCs, forming columns in a pale mucoid matrix in which isolated neurons float. These so-called glioneuronal elements are observed in both simple and complex forms. The latter exhibits an additional glial or neuronal cell population forming nodules which mimic low-grade gliomas. A third, “nonspecific,” form of DNT has also been reported. Literature also documents rare cases of malignant transformation. The closest differential diagnoses that exist are ganglioglioma and oligodendroglioma. However, the absence of mass effect, peritumoral edema, and cortical dysplasia and localization favor DNT over gliomas.
Surgical excision remains necessary because it provides the best chance to cure epilepsy and prevents hemorrhagic complications., Nevertheless, it is of utmost importance to distinguish DNTs from glioma because DNTs can be cured by surgery alone. Earlier intervention can prevent the physical and psychosocial damage resulting from chronic seizures and can improve the prognosis for these young patients. The optimal time for surgical intervention in children with these tumors remains unclear. Ramantani et al. studied 29 patients and reported that shorter seizure duration may lead to a better cognitive outcome.
Moreover, the aggressiveness criteria, including mitosis, ischemic necrosis, capillary proliferation, nuclearatypia, and meningeal involvement, are usually observed in malignant tumors but do not exclude the diagnosis of DNT., It is important to be aware of this entity because it can histopathologically mimic an oligodendroglioma or neurocytoma which needs more aggressive therapeutic interventions. It is thus important that the diagnosis of DNT is taken into consideration whenever all of thefollowing criteria are present: (i) partial seizures with or without secondary generalization, onset before the age 20 years; (ii) no progressive neurological deficit; (iii) predominantly cortical topography of a supratentorial lesion, best demonstrated on MR imaging (MRI); and (iv) no mass effect on CT or MRI, except if related to a cyst, and no peritumoral edema. With this perspective, the diagnosis of DNT must be the result of a multidisciplinary discussion between neurosurgeon, neuroradiologists, and neuropathologists.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2]