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Background

D.N.T. stands for Dysembryoplastic Neuroepithelial Tumor-Like Neoplasm. These rare brain tumors occur in children and young adults and commonly present in the midline region of the septum pellucidum of the brain. Patients present with the usual symptoms of a mass lesion in the brain with headache, nausea and vomiting, and visual disturbances. These tumors appear to behave in a benign fashion.

OUTLINE

Epidemiology  
Disease Associations  
Pathogenesis  
Laboratory/Radiologic/Other Diagnostic Testing  
Gross Appearance and Clinical Variants  
Histopathological Features and Variants  
Special Stains/Immunohistochemistry/Electron Microscopy  
Differential Diagnosis  
Prognosis  
Treatment  
Commonly Used Terms  
Internet Links  

EPIDEMIOLOGY CHARACTERIZATION
AGE RANGE-MEDIAN Ranged in age from 6 to 35 years (mean age, 21.5 years)
SEX (M:F)
Five female and five male

 

PATHOGENESIS CHARACTERIZATION
APOPTOSIS  


Bcl-2, bcl-x, and bax expression in dysembryoplastic neuroepithelial tumors.

Prayson RA.

Department of Anatomic Pathology, Cleveland Clinic Foundation, OH 44195, USA.

Clin Neuropathol 2000 Mar-Apr;19(2):57-62 Abstract quote

BACKGROUND: Bcl-2, bcl-x and bax are regulatory proteins which are variably expressed in brain tissue and are known to be involved in the regulation of apoptosis; bcl-2 and bcl-x inhibit apoptosis and bax generally promotes apoptosis. This study is a retrospective clinicopathologic and immunohistochemical review of 18 dysembryoplastic neuroepithelial tumors (DNTs), specifically looking for evidence of aberrant expression of apoptosis regulatory proteins which may promote the survival of one or more of the cellular constituents of the tumor.

MATERIALS AND METHODS: Eighteen patients (11 males) with DNTs comprise the study group. Patients at the time of surgery ranged in age from 2.1-52 years (mean 16.1 years). Mean seizure duration prior to surgery was 6.4 years (n = 16 patients). Sixteen patients were alive with markedly reduced or no seizures at a mean postsurgical follow-up interval of 63 months; 2 patients were lost to follow-up.

RESULTS: All tumors were characterized by an admixture of oligodendroglial cells, neurons and astrocytic cells, focally arranged against a microcystic background. Coexistent cortical dysplasia was noted in 14 evaluable cases. Mitotic figures were rarely noted in 2 tumors. MIB-labeling indices ranged from 0-0.6 (mean 0.2). Astrocytes which were part of the tumor stained with all three antibodies in all cases. The oligodendroglial-like cells of DNT stained positively for bcl-2 in 2/17 tumors, bcl-x in 10/17 tumors, and bax in 12/17 tumors. The neuronal cell component of the DNT stained positively with bcl-2 in 15/17 tumors, bcl-x in 5/17 tumors, and bax in 8/17 tumors.

CONCLUSION: Aberrant expression of apoptosis-associated proteins, similar to what has been previously described in gangliogliomas (another epilepsy-related, dysplasia-associated tumor), may play a role in the pathogenesis of DNT.

CHROMOSOMAL ABNORMALITIES  


Chromosome 1p allelic loss by fluorescence in situ hybridization is not observed in dysembryoplastic neuroepithelial tumors.

Prayson RA, Castilla EA, Hartke M, Pettay J, Tubbs RR, Barnett GH.

Department of Neurological Surgery, Cleveland Clinic Foundation, OH 44195, USA.

 

Am J Clin Pathol 2002 Oct;118(4):512-7 Abstract quote

Differentiation of dysembryoplastic neuroepithelial tumor (DNT) from cystic low-grade oligodendroglioma, particularly in a limited biopsy orfragmented specimen, may be impossible. Research has shown that allelic loss of chromosome 1p is a relatively common finding in oligodendrogliomas. Little is known about chromosome 1p status in DNT.

We retrospectively evaluated 14 DNTs for loss of heterozygosity (LOH) on chromosome 1p by fluorescence in situ hybridization (FISH) and compared the results with 1p FISH analysis in 57 low-grade oligodendrogliomas (World Health Organization grade II). The 14 DNTs arose in 8 females and 6 males (mean age, 20.9 years at the time of surgery). All 14 DNTs were 1p intact by FISH analysis. The 57 low-grade oligodendrogliomas arose in 31 males and 26 females (mean age, 43.2 years). LOH on chromosome 1p was present in 31 (54%) of 57 tumors; the remaining 26 tumors were 1p intact. LOH on chromosome 1p is not a feature of DNTs.

LOH on chromosome 1p may be a useful differential diagnostic feature (favoring oligodendroglioma) in a subset of cases in which specimen fragmentation or size raises the differential diagnosis of DNT vs oligodendroglioma.

GLUTAMATE


Dysembryoplastic neuroepithelial tumour (DNT). Is the mechanism of seizures related to glutamate? An immunohistochemical study.

Adamek D, Korzeniowska A, Morga R, Lopatka P, Jelenska-Szygula I, Danilewicz B.

Department of Neuropathology, Institute of Neurology, Jagiellonian University, Medical College, Krakow, Poland.

Folia Neuropathol 2001;39(2):111-7 Abstract quote

Dysembryoplastic neuroepithelial tumour (DNT) is a rare low-grade, mixed neuronal and glial tumour, usually associated with pharmacologically intractable, complex partial or generalised seizures which date from childhood. The prognosis after surgery is favourable.

We present a classic case of DNT occurring in an 18-year-old male, who presented simple partial seizures without signs of raised intracranial pressure. CT and MR demonstrated focal mass located in the right temporal lobe. Histologically there were found the features of a typical DNT architecture with mixed cellular composition. The response to surgery was excellent. The tumour has not recurred, and the control of seizures remained good. Immunostaining for glutamate receptor GluR-2 showed stronger immunopositivity in neurones dispersed within the tumour and especially in margins of lesion as compared with apparently normal cerebral cortex.

The expression of both excitatoryamino acid transporterproteins EAAT1 and EAAT2 was weaker then in normal cortex and uneven. This perhaps may explain the mechanism of seizures (elevated glutaminergic stimulation), and may suggest the excitotoxic damage of neurones.

 

LABORATORY/RADIOLOGIC/OTHER TESTS CHARACTERIZATION
Radiographs  
CT scan and MRI

Tumors extended into the lateral ventricles from the septal region and obstructed the foramen of Monro with varying degrees of hydrocephalus

Lobular, well-delineated, hypointense to brain on T1-weighted magnetic resonance imaging, and hyperintense on T2-weighted images

Uniformly nonenhancing or showed only minimal peripheral enhancement


Dysembryoplastic neuroepithelial tumors: MR appearance.

Koeller KK, Dillon WP.

Department of Radiology, University of California, San Francisco 94143-0628.

 

AJNR Am J Neuroradiol 1992 Sep-Oct;13(5):1319-25 Abstract quote

PURPOSE: Dysembryoplastic neuroepithelial tumor (DNT) is a newly described, pathologically benign tumor arising within the supratentorial cortex and having a 100% association with partial complex seizures. We reviewed the MR appearance of the brains of six patients with DNT, without and with administration of gadolinium-DTPA, emphasizing the clinical and radiologic features.

METHODS: The MR images in six patients (five male, one female) with pathologically proved DNT were reviewed. Five had partial complex seizures and one had partial simple seizures. Age at onset of partial seizures ranged from 2 to 19 years. Scans were obtained with conventional T1 and T2 weighting without and with the administration of gadolinium-DTPA. All patients had craniotomies for medically refractory seizures and pathologic examination of all specimens was available for review.

RESULTS: MR demonstrated a focal cortical mass in all patients. Five were located in the temporal lobe and one was located within the occipital lobe. Two showed enhancement with gadolinium-DTPA. Calcification occurred in one lesion. Common features included very low signal intensity on T1-weighted images and high signal on T2-weighted images, similar to cerebrospinal fluid. Proton density images demonstrated slightly higher signal intensity in the lesion than cerebrospinal fluid. The margin of the tumor is well-circumscribed and may remodel the adjacent calvarium.

CONCLUSIONS: DNT, a newly described pathologic entity resulting in chronic, often medically, intractable seizures, has characteristic features on MR that allow it to be suggested in the differential diagnosis. These lesions may simulate benign cysts; however, increased signal intensity on proton density images should prompt further investigation in the proper clinical setting. Differentiation from low-grade astrocytomas and ganglioglioma is not possible by MR.


Dysembryoplastic neuroepithelial tumors: MR findings.

Kuroiwa T, Kishikawa T, Kato A, Ueno M, Kudo S, Tabuchi K.

Department of Radiology, Saga Medical School, Japan.

J Comput Assist Tomogr 1994 May-Jun;18(3):352-6 Abstract quote

OBJECTIVE: We report MR findings in three patients with dysembryoplastic neuroepithelial tumor (DNT), which is a recently described benign tumor in childhood or young adolescents.

MATERIALS AND METHODS: The MR studies of three patients with surgically proven DNT were reviewed. All cases presented with partial complex seizures. Axial and coronal T1- and T2-weighted MR imaging of the head was performed using a 1.5 T MR unit. T1-weighted imaging after Gd-DTPA was also performed.

RESULTS: The tumors were located mainly in the cortical to subcortical area with very little perifocal mass effects on MR imaging. They were essentially hypointense on T1-weighted imaging and hyperintense well-demarcated mass on T2-weighted imaging and retained a thick gyrus-like configuration within the lesions. None of them exhibited contrast enhancement after administration of Gd-DTPA.

CONCLUSION: Differentiation of DNT from gangliogliomas or other low grade gliomas is possible using these MR features and is important because DNT does not recur after epilepsy surgery, therefore postoperative radiation and chemotherapy are not needed.


Dysembryoplastic neuroepithelial tumor: radiological findings (including PET, SPECT, and MRS) and surgical strategy.

Lee DY, Chung CK, Hwang YS, Choe G, Chi JG, Kim HJ, Cho BK.

Department of Neurosurgery, Seoul National University College of Medicine, Korea.

 

J Neurooncol 2000 Apr;47(2):167-74 Abstract quote

In order to elucidate the radiological features of dysembryoplastic neuroepithelial tumor (DNT), and to clarify the optimal surgical strategy for this tumor, the authors retrospectively analyzed 20 cases of DNT treated at our institution.

Magnetic resonance (MR) imaging (all cases), 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) (eight cases), ictal/interictal Tc99m-HMPAO single photon emission computed tomography (SPECT) (seven and five cases respectively) and proton magnetic resonance spectroscopy (1H MRS) (one case) were performed preoperatively. Invasive monitoring/intraoperative electrocorticography (ECoG) was performed in four cases in order to determine the epileptogenic zone.

A well-demarcated lobulating tumor located in the cortical with/without subcortical area was the typical MR finding. 18F-FDG PET showed glucose hypometabolism in all cases. Ictal Tc99m-HMPAO SPECT showed hyperperfusion of the lesion in three cases and interictal Tc99m-HMPAO SPECT showed hypoperfusion of the lesion in one case. 1H MRS showed nonspecific findings. Gross total resection was performed in all cases. Histologically, associated cortical dysplasia was found in 11 cases. The mean duration of follow-up after surgery was 37.9 months, and the overall seizure free rate was 90%.

Follow-up MR imaging was performed in 14 cases (mean duration of follow-up: 21.6 months) and showed no recurrence of tumor in any of these cases. Invasive monitoring/intraoperative ECoG and the presence of cortical dysplasia showed no significant relationship with seizure control rate (p = 1.25 and p = 1.62 respectively).

PET SCAN  


Positron emission tomography using [18F] fluorodeoxyglucose and [11C] l-methionine to metabolically characterize dysembryoplastic neuroepithelial tumors.

Kaplan AM, Lawson MA, Spataro J, Bandy DJ, Bonstelle CT, Moss SD, Manwaring KH, Reiman EM.

Division of Neurology, Phoenix Children's Hospital/Good Samaritan Regional Medical Center, AZ 85006, USA.

J Child Neurol 1999 Oct;14(10):673-7 Abstract quote

Dysembryoplastic neuroepithelial tumors are unique and benign congenital tumors occurring frequently in children and adolescents. Differentiation from other low-grade tumors is important for management.

Five patients with confirmed dysembryoplastic neuroepithelial tumors were studied with positron emission tomography using glucose and protein metabolic uptake in an attempt to categorize these tumors metabolically. Functional brain mapping also was obtained to aid in operative management. Results of the study conclude that dysembryoplastic neuroepithelial tumors, although having similar neuroimgaing characteristics to other low-grade tumors, are distinguished by a unique metabolic profile. They are inactive tumors with no significant glucose or protein metabolic activity.

The combination of preoperative positron emission tomographic metabolic studies with functional brain mapping allowed for prediction of tumor type, defined eloquent areas of cortical function, and improved approach and resection of the tumors with minimal risk of neurologic impairment.

 

CLINICAL VARIANTS CHARACTERIZATION
GENERAL  


Dysembryoplastic neuroepithelial tumor. Features in 16 patients.

Raymond AA, Halpin SF, Alsanjari N, Cook MJ, Kitchen ND, Fish DR, Stevens JM, Harding BN, Scaravilli F, Kendall B, et al.

Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, UK.

 

Brain 1994 Jun;117 ( Pt 3):461-75 Abstract quote

Dysembryoplastic neuroepithelial tumour (DNT) is a newly recognized brain mass lesion with distinctive pathological features and a favourable prognosis.

We reviewed the clinical, electroencephalographic, neuroimaging and pathological features of 16 patients with DNT who underwent surgery; only one patient did not have epilepsy. Mean age at seizure onset was 9.5 years (range: 1 week to 30 years) and surgery 17 years (range: 7 months to 37 years). The mean verbal IQ was 94.6 (range: 79-110) and performance IQ 105 (range: 79-130) (n = 10). The EEG was abnormal in all cases reviewed (n = 13): localized slow activity was seen in 12 and interictal spiking in 10 patients, being less extensive than or concordant with the lesion in three and more extensive than or distant to the lesion in seven. X-ray CT was normal in three out of 11 patients. Magnetic resonance imaging provided detailed anatomical information: the lesion was predominantly intracortical, although in six patients, there was also white matter involvement. The lesion involved the temporal lobe in all but one patient where it was in the cingulate gyrus. Of the temporal lobe cases, MRI showed that the lesion involved, or was in close proximity to, mesial temporal structures in 11 out of 14 patients. Other magnetic resonance features included: circumscribed hyperintensity on long TE/TR images (10 patients), hypointensity on short TR images (12 patients), and cyst formation (five patients). Calcification was seen on CT in four patients. Post surgical follow-up ranged from 8 to 30 months (mean 16.2 months): 12 patients are seizure free and two have a > 80% reduction in seizure frequency (n = 14).

Histopathological characteristics included a heterogeneous composition in all cases, calcification (13 cases), dysplastic features (12 cases) and isolated foci of subpial spread (five cases). The presence of occasional mitoses in 12 cases and immunoreactivity to the proliferating cell nuclear antigen in six cases indicate that these lesions have cellular proliferative activity and that there may be a need to follow these patients postoperatively.


Dysembryoplastic neuroepithelial tumor: morphological, immunocytochemical, and deoxyribonucleic acid analyses in a pediatric series.

Taratuto AL, Pomata H, Sevlever G, Gallo G, Monges J.

Instituto de Investigaciones Neurologicas Raul Carrea, Fundacion para la Lucha contra las Enfermedades Neurologicas de la Infancia, Buenos Aires, Argentina.

Neurosurgery 1995 Mar;36(3):474-81 Abstract quote

Overtreatment by radiotherapy and/or chemotherapy for central nervous system tumors in infancy and childhood may be deleterious, so the recognition of surgically curable clinicopathological entities is mandatory.

The dysembryoplastic neuroepithelial tumor is a complex multinodular lesion consisting of glial nodules, associated with a specific glioneuronal element and/or with focal cortical dysplasia, and occurring in young patients presenting with intractable, mostly complex partial, seizures without neurological deterioration. We report on 14 patients; 9 were from a series of 600 pediatric patients with intracranial central nervous system tumors studied at a single institution from 1988 to 1993, and 5 were referred from other pediatric hospitals. Six tumors were frontal, six were temporal, one was parietal, and one was occipitoparietal. Computed tomographic scans disclosed hypodense lesions with cystic appearances in 4 patients and slight focal postcontrast enhancements in only 2 patients, whereas magnetic resonance imaging, available for 7 of 14 patients, showed hypointense lesions in T1-weighted images and hyperintense lesions in T2-weighted images. Deformities of the overlying cranium were also observed in five patients.

The age range at the time of surgery (excluding a 20-year-old male patient who underwent surgery at the main pediatric hospital) was 2.6 to 13 years, with a mean of 6.68 years. The male to female patient ratio was 10:4, and the duration of symptoms was 0.2 to 6 years.


Dysembryoplastic neuroepithelial tumor.

Cabiol J, Acebes JJ, Isamat F.

Department of Neurosurgery, Ciutat Sanitaria y Universitaria de Bellvitge, Universitat de Barcelona, Torras i Pujalt 1, E-08022 Barcelona, Spain

CRITICAL REVIEWS IN NEUROSURGERY 1999 Mar 24;9(2):116-125 Abstract quote

Dysembryoplastic neuroepithelial tumors (DNTs) were first described in 1988. A DNT is a cortical tumor that produces enlargement of a gyrus, forming a megagyrus that exceeds the normal thickness of the cortex.

This tumor is generally seen in young patients with a long-standing history of drug-resistant and disabling seizures mostly of the complex partial type. No neurological deficits are found between the interictal periods in the majority of the reported cases. A general agreement exists over the clinical and radiological manifestations of a DNT as well as the benign biological behavior. Two pathological variants of DNT have been recognized: the single form, composed only of the so-called specific glioneuronal element, and the complex form that additionally shows glial nodules and foci of cortical dysplasia. Nevertheless, and despite the benign biological course, nuclear atypias, cellular monstruosities, foci of necrosis and mitosis can also be found. Surgical eradication of the tumor will usuallly have a good prognosis, without recurrences and with a positive control to seizure-free clinical outcome. Controversy continues to exist over a hamartomatous or a neoplastic origin of this lesion. The DNT has been placed among the neuronal and mixed neuronal-glial neoplasms in the revised World Health Organization (WHO) brain tumor classification, a category that includes the gangliogliomas and the central neurocytomas.

Ultrastructural studies and immunostaining techniques may suggest that these three lesions represent different spectrums of the same condition. This paper reviews the most recent publications to offer a better understanding of DNTs and their implications in diagnosis and management.

VARIANTS  
CEREBELLUM  


Dysembryoplastic neuroepithelial tumour of the cerebellum.

Kuchelmeister K, Demirel T, Schlorer E, Bergmann M, Gullotta F.

Institut fur Neuropathologie der Universitat, Munster, Germany.

Acta Neuropathol (Berl) 1995;89(4):385-90 Abstract quote

A case of dysembryoplastic neuroepithelial tumour of the cerebellum occurring in a 28-year-old woman is presented. The lesion extended from the cortex of the inferior vermis upwards into the white matter.

Histologically, it exhibited areas of microcystic cerebellar astrocytoma and glial regions with hamartomatous blood vessels as well as areas with oligodendrocyte-like cells (OLC) with a delicate, fibrillary stroma lying in a mucinous, often microcystic matrix. The OLC showed prominent rosette formation and immunohistochemical features suggesting neuronal, i.e. granule cell, differentiation.

INTRACEREBRAL HEMORRHAGE  


Spontaneous intralesional haemorrhage in dysembryoplastic neuroepithelial tumours: a series of five cases.

Thom M, Gomez-Anson B, Revesz T, Harkness W, O'Brien CJ, Kett-White R, Jones EW, Stevens J, Scaravilli F.

Department of Neuropathology, National Hospital for Neurology and Neurosurgery, London.

J Neurol Neurosurg Psychiatry 1999 Jul;67(1):97-101 Abstract quote

Five patients with dysembryoplastic neuroepithelial tumour (DNT) showing extensive secondary haemorrhage, a finding not previously associated with these neoplasms, are described.

The clinical presentations, neuroimaging findings, and histopathological features of these patients are reviewed. One patient, a previously asymptomatic 12 year old girl, presented with an acute intracerebral haemorrhage into a DNT. A further four young adults with histories of intractable partial and generalised seizures dating from childhood showed significant chronic haemorrhages within DNT, the MRI appearances in one patient giving a false impression of a cavernoma.

Histopathology disclosed vascular abnormalities within these tumours which, together with other factors discussed, may have predisposed these tumours to haemorrhage.

MULTIFOCAL  



Dsyembryoplastic neuroepithelial tumour with discrete bilateral multifocality: further evidence for a germinal origin.

Whittle IR, Dow GR, Lammie GA, Wardlaw J.

Department of Clinical Neuroscience, Western General Hospital, Edinburgh, UK.

Br J Neurosurg 1999 Oct;13(5):508-11 Abstract quote

We report the case of a middle aged woman who developed refractory complex partial seizures in her early twenties. She had a right coloboma and neurological examination was normal. Neuropsychological assessments revealed mild impairments of non-verbal memory, and visuospatial and constructional difficulties.

Serial CT and MRI showed multiple nodular abnormalities in her mid-brain, diencephalon, subependymal region and both mesial temporal lobes. EEG recording revealed a right medial temporal focus. She underwent en bloc temporal lobectomy. The surgical pathology revealed mesial temporal dysembryoplastic neuroepithelial tumour (DNET) in association with extensive, contiguous neocortical dysplasia. The proliferation marker MIB-1 revealed up to 2% labelling in tumour areas resembling conventional oligodendroglioma. In the two years since surgery she has been seizure free and the remaining MR brain abnormalities have not changed. The very unusual centripetal MRI pattern of discrete multifocal lesions with the characteristic T1 and T2 features of DNET would support the dysembyroplastic germinal origin that was proposed by Daumas-Duport et al. (1988) in their original description of the lesion.

The neuroradiological, neuropathological and clinical features of this case are compared with the two previous cases of multifocal DNET.

 

HISTOLOGICAL TYPES CHARACTERIZATION
GENERAL

Lobular microcystic appearance with relatively well-defined borders

Multiple, discrete microscopic nodules with the principal tumor cells with uniformly round and hyperchromatic nuclei, and prominent perinuclear clearing resembling oligodendrocytes

Oligodendrocyte-like cells (OLCs) were clustered tightly about perivascular spaces, in some instances forming an alveolar or rosette-like pattern

Specific glioneuronal element with tumor cells arranged parallel to fibrillar zones in a well-defined linear array

Neurons appeared to be part of the lesions and appeared to float in a mucoid or finely fibrillar background

None of the neurons were binucleate or displayed dysplastic features. Perineuronal satellitosis was absent

No glomeruloid vascular proliferation, Rosenthal fibers, or eosinophilic granular bodies were noted

Mitotic figures were absent to rare


Dysembryoplastic neuroepithelial tumours.

Daumas-Duport C.

Department of Pathological Anatomy, Sainte-Anne Hospital, Paris, France.

Brain Pathol 1993 Jul;3(3):283-95 Abstract quote

Dysembryoplastic neuroepithelial tumours (DNTs) are a group of supratentorial cortical benignant lesions that superficially resemble mixed oligo-astrocytomas, oligodendrogliomas or astrocytomas. Clinically these tumours are associated with partial seizures beginning before the age of 20 years, with no neurologic deficit and no stigmata of phacomatosis.

In the revised WHO classification, DNTs have been incorporated among the category of neuronal and mixed neuronoglial tumours. This classification describes a histologic variant characterized by the following criteria: cortical location, multinodular architecture--the nodule being made of multiple variants looking like astrocytomas, oligodendrogliomas or oligo-astrocytomas, foci of dysplastic cortical disorganization and the presence of a glioneuronal element showing a columnar structure perpendicular to the cortical surface. A study of 14 cases for which only a specific glioneuronal element could be identified demonstrated that this specific element is sufficient for diagnosing DNTs and that the spectrum of DNTs includes a simple form with a unique glioneuronal element.

Preoperative imaging follow-up data, in the series of 23 simple and complex forms, indicated that DNTs are perfectly stable. However, these tumours may show a high MIB 1 labeling index.


Dysembryoplastic neuroepithelial tumors: nonspecific histological forms -- a study of 40 cases.

Daumas-Duport C, Varlet P, Bacha S, Beuvon F, Cervera-Pierot P, Chodkiewicz JP.

Department of Pathology, Sainte-Anne Hospital, Cochin Port-Royal University, Paris, France.

J Neurooncol 1999 Feb;41(3):267-80 Abstract quote

OBJECTIVE: To demonstrate that DNTs include a large morphological spectrum of tumors that cannot be histologically distinguished from conventional categories of gliomas.

METHODS: All tumors from patients who underwent epilepsy surgery in Sainte-Anne hospital (Paris) that histologically resembled gliomas and did not conform to current histological criteria for DNTs or gangliogliomas were entered in the study.

RESULTS: According to the WHO histological classification, the 40 tumors resembled: pilocytic astrocytomas (4 cases), astrocytomas (16 cases), anaplastic astrocytoma (1 case), oligodendrogliomas (10 cases), oligo-astrocytomas (8 cases) or anaplastic oligo-astrocytomas (1 case). However foci of cortical dysplasia could be observed in 47% of the cases. Clinical presentation and imaging features were strikingly similar to that observed in typical DNTs. Although surgical removal was incomplete in 28% of the cases and none of the patients underwent chemo or radiotherapy, none of the tumors recurred (mean follow-up: 7 years). Moreover, serial preoperative imaging in 26 patients (mean follow-up: 4.5 years) demonstrated that these lesions were perfectly stable.

CONCLUSIONS: Whatever the histological appearance of a glial tumor, the diagnosis of DNT must be considered when all the following criteria are associated: (1) partial seizures, with or without secondary generalization, beginning before the age 20 years, (2) no neurological deficit or stable congenital deficit, (3) cortical topography of the lesion as better demonstrated by MRI and (4) no mass effect on imaging.


Histological heterogeneity of dysembryoplastic neuroepithelial tumour: identification and differential diagnosis in a series of 74 cases.

Honavar M, Janota I, Polkey CE.

Department of Neuropathology, Institute of Psychiatry, King's Heath Trust, London, UK.

 

Histopathology 1999 Apr;34(4):342-56 Abstract quote

AIMS: In a retrospective study of resected specimens from 416 patients being treated for long-standing epilepsy, 74 cases of dysembryoplastic neuroepithelial tumour (DNT) were encountered that were all characteristically composed of small round oligodendroglia-like cells (OLC), astrocytes and mature neurones in varying proportions. The architectural patterns, histological, immunohistochemical and ultrastructural features and results of cell proliferation studies and postoperative follow-up are described to facilitate the identification of DNT and to differentiate it from other intrinsic neoplasms that commonly present with seizures.

METHODS AND RESULTS: The tumours presented with early onset of seizures, at a median age of 7 years, without the signs of raised intracranial pressure. A majority of the lesions were located in the temporal lobe (n = 59), with fewer cases in the frontal (n = 8), parietal (n = 6) and occipital lobes (n = 1), and ranged in size from 10 to 70 mm; 33 were cystic. Histologically three types could be distinguished, multinodular, solitary nodular and diffuse. The first type (37.8%) had the features of a typical DNT with multinodular architecture and mixed cellular composition. The second type (33.8%) consisted of a solitary nodule, while the third (28.4%) was a diffuse tumour, both composed of a similar mixture of cells as the multinodular DNT. The lesions were seen in the neocortex and white matter and tumours in the temporal lobe often involved the amygdala and hippocampus. The presence of myxoid matrix, microcystic change, calcification and leptomeningeal involvement were common. Dysplastic neurones at the periphery of the tumour and abnormalities in cortical lamination in the adjacent neocortex were found in about one-third of the resections. Rare mitotic figures were encountered in eight of the tumours and necrosis was found in two. Immunocytochemistry for glial fibrillary acidic protein (GFAP) and neuronal markers neuron-specific enolase, synaptophysin and neurofilament (RT 97) assists in establishing the diagnosis, highlighting the astrocytic and neuronal components, and the OLC, by the absence of expression of GFAP. Electron microscopy showed that in some cases OLC show neuronal differentiation. Although the proliferating cell nuclear antigen labelling index varied between 0 and 45.5%, 20 of the 51 tumours stained failed to express the antigen, in keeping with the indolent nature of this neoplasm. The response to surgery was excellent; none of the tumours have recurred, and the control of seizures remained good.

CONCLUSIONS: Despite some histological heterogeneity, the clinical and pathological features and indolent biological behaviour indicate that these tumours constitute a single distinct entity. The spectrum of morphological appearances of DNT is broader than has been previously reported, the recognition of which is needed to avoid unnecessary neoadjuvant therapy.


Dysembryoplastic neuroepithelial tumor-like neoplasm of the septum pellucidum: a lesion often misdiagnosed as glioma: report of 10 cases.

Baisden BL, Brat DJ, Melhem ER, Rosenblum MK, King AP, Burger PC.

Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.

Am J Surg Pathol 2001 Apr;25(4):494-9 Abstract quote

The authors report a series of 10 low-grade neoplasms arising in the midline anteriorly in the region of the septum pellucidum with many of the histologic features of dysembryoplastic neuroepithelial tumor (DNT).

The patients (five female, five male) ranged in age from 6 to 35 years (mean age, 21.5 years). The most common presenting symptoms were headache, nausea and vomiting, and visual disturbances. Radiographically, the tumors extended into the lateral ventricles from the septal region and obstructed the foramen of Monro. Varying degrees of hydrocephalus were present. The lesions were lobular, well-delineated, hypointense to brain on T1-weighted magnetic resonance imaging, and hyperintense on T2-weighted images. They were uniformly nonenhancing or showed only minimal peripheral enhancement. The tumors, in aggregate, had the histologic features of DNT. These included a mucin-rich background, oligodendrocyte-like cells, "floating neurons," and a "specific glioneuronal element." Seven patients underwent gross total resection and two underwent subtotal resection. No patients received adjuvant chemotherapy or radiotherapy. On follow-up (n = 6; median, 14 months), all tumors had either not recurred or were radiologically stable. On the basis of both neuroimaging and histopathology, DNT-like lesions should be considered in the differential diagnosis of midline intraventricular tumors in children and young adults.

Distinction from more aggressive neoplasms is essential because these tumors appear to behave in a benign fashion.


Dysembryoplastic neuroepithelial tumors: report of 10 cases from a center where epilepsy surgery is not done.

Tatke M, Suri VS, Malhotra V, Sharma A, Sinha S, Kumar S.

Department of Pathology, G.B Pant Hospital, New Delhi, India.

Pathol Res Pract 2001;197(11):769-74 Abstract quote

Dysembryoplastic neuroepithelial tumor (DNT) is a recently recognized tumor entity with distinctive clinicopathological features and an excellent long-term prognosis.

We report 10 cases of DNT out of neurosurgical specimens sent for histopathological examination since 1994. Epilepsy surgery is not done at our center, and all the cases were sent with a clinical diagnosis of glioma. On histopathological examination, all the 10 cases contained the specific glioneuronal element. In 6 cases, glial nodules were noted in addition. This study therefore reports 4 cases of simple DNT and 6 cases of complex DNT. There was no nuclear atypia or mitosis in any of the cases. Proliferative index by PCNA varied from negative to <1%.

It is very important to recognize this entity, as surgery cures the patient, and radiotherapy or chemotherapy is not required.

VARIANTS  
GANGLIOGLIOMA  


Composite ganglioglioma and dysembryoplastic neuroepithelial tumor.

Prayson RA.

Department of Anatomic Pathology, Cleveland Clinic Foundation, Ohio 44195, USA.

Arch Pathol Lab Med 1999 Mar;123(3):247-50 Abstract quote

Both ganglioglioma and dysembryoplastic neuroepithelial tumors are well-recognized glial-neuronal neoplasms associated with chronic epilepsy and cortical dysplasia (neuronal migration abnormalities).

The exact relationship between these 2 glial-neuronal tumors continues to be debated. This article reports a case of a composite ganglioglioma and dysembryoplastic neuroepithelial tumor occurring in a 36-year-old woman in the left temporal lobe region. The resection histologically demonstrated distinct areas of ganglioglioma and dysembryoplastic neuroepithelial tumor. A focal area of cortical dysplasia is also identified. The MIB-1 labeling indexes in both components were low (<1% of tumor cell nuclei).

The coexistence of these 2 lesions and cortical dysplasia suggest a possible etiologic relationship between these 2 tumors.

MALIGNANT  


Malignant transformation of a dysembryoplastic neuroepithelial tumor after radiation and chemotherapy.

Rushing EJ, Thompson LD, Mena H.

Ann Diagn Pathol. 2003 Aug;7(4):240-4. Abstract quote

We describe a case of anaplastic astrocytoma in a 14-year-old boy arising at the site of a dysembryoplastic neuroepithelial tumor (DNT) 3 years after combined radiation and chemotherapy.

The subtotally excised superficial right temporoparietal tumor was originally diagnosed as mixed oligoastrocytoma in 1974; the patient was treated with radiation therapy postoperatively. One year later he underwent a craniotomy to remove cyst fluid and no change was reported in the size of the residual tumor. Postoperatively, he received a 6-week course of chemotherapy (lovustine, CCNU). He remained clinically and radiographically stable until 3 years later, when seizure activity returned and imaging studies were consistent with tumor recurrence. He was lost to follow-up until 1986, when records showed that he had died.

Review of the initial biopsy showed cortical fragments containing abundant calcifications and multinodular structures typical of the complex form of DNT, in addition to specific glioneuronal elements. The Ki-67 labeling index ranged from 0.1% to 3% focally. The specimen from the third surgery showed an anaplastic astrocytoma (Ki-67 up to 12%) and morphologic features characteristic of radiation effect. This is the first documented case of malignant transformation of DNT following radiation and adjuvant chemotherapy.

The implications of malignant transformation in subtotally excised complex DNTs and the intriguing issue of the contribution of radiation/chemotherapy are discussed.

MELANOTIC DIFFERENTIATION  

Melanotic differentiation in dysembryoplastic neuroepithelial tumor.

Elizabeth J, Bhaskara RM, Radhakrishnan VV, Radhakrishnan K, Thomas SV.

Department of Pathology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India.

Clin Neuropathol 2000 Jan-Feb;19(1):38-40 Abstract quote

Dysembryoplastic neuroepithelial tumor (DNT) is an uncommon intracranial tumor which is usually encountered in patients with medically intractable complex partial seizures of temporal lobe origin. Melanotic differentiation in a DNT has not been reported previously.

Herewith we report a case of DNT with unique melanotic differentiation in a 23-year-old female who presented with medically intractable epilepsy. She underwent craniotomy and tumor decompression with a good outcome. We present the histopathological features of DNT with melanotic differentiation and discuss its prognostic significance.

ROSETTE FORMING  


A rosette-forming glioneuronal tumor of the fourth ventricle: infratentorial form of dysembryoplastic neuroepithelial tumor?

Komori T, Scheithauer BW, Hirose T.

Department of Pathology and Laboratory Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.

Am J Surg Pathol 2002 May;26(5):582-91 Abstract quote

Eleven cases of a distinctive tumor of the posterior fossa are described. The patients (age range 12-59 years) presented with headache and/or ataxia.

Neuroimaging revealed a relatively discrete, focally enhancing mass(es) primarily involving the aqueduct, fourth ventricle, and cerebellar vermis. Hydrocephalus was present in seven cases, and two lesions were multicentric. In two cases a significant increase in tumor size was documented. Gross total or subtotal resections were achieved in 10 cases. One patient underwent biopsy alone and another received postoperative irradiation.

Histologically, two components were identified in all cases. One consisted of neurocytes forming neurocytic and/or perivascular pseudorosettes in a fibrillary, partly microcystic matrix. The second, astrocytic component resembled pilocytic astrocytoma in 10 cases and consisted of fibrillated spindle cells with oval nuclei associated with occasional Rosenthal fibers, granular bodies, glomeruloid capillaries, and microcalcifications. Regionally, this component was more diffuse and patternless, consisting of sheets of round to oval, oligodendrocyte-like cells. Rare ganglion cells were seen in four cases. The rosettes were consistently synaptophysin and MAP-2 immunoreactive, whereas the spindle cells were positive for S-100 protein and glial fibrillary acidic protein. Overall, atypia was minimal; no mitoses were found, and Ki67 labeling indices were low.

Ultrastructurally, the neurocytic cells featured processes containing microtubules and occasional dense core granules. Mature synapses were found in one of the four cases studied. Although the histologic features of this unique tumor superficially resemble those of dysembryoplastic neuroepithelial tumor, rosette formation by neuronal cells, the frequent presence of a pilocytic astrocytoma component, and the growing nature of the lesion argue against that diagnosis, as does occasional multifocality.

 

SPECIAL STAINS/IMMUNOHISTOCHEMISTRY CHARACTERIZATION
GENERAL  


Dysembryoplastic neuroeptihelial tumor (DNT): an immunohistochemical and ultrastructural study.

Hirose T, Scheithauer BW, Lopes MB, VandenBerg SR.

Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota 55905.

J Neuropathol Exp Neurol 1994 Mar;53(2):184-95 Abstract quote

To assess the range of differentiation of the cells comprising dysembryoplastic neuroepithelial tumor (DNT), particularly the oligodendrocyte-like cells (OLC), 14 DNT were immunochemically studied with a spectrum of neuronal and glial markers.

Eight tumors were also studied ultrastructurally. Neurofilament protein, class III beta-tubulin, and synaptophysin preparations stained a few OLC in two, six and one lesion, respectively. In addition, many OLC within a single cortical nodule were reactive for class III beta-tubulin. The vast majority of OLC were strongly S-100 protein positive. Glial fibrillary acidic protein labeled a fair number of OLC in two cases and one nodule consisted almost entirely of immunoreactive astrocytes. Ultrastructurally, many OLC resembled oligodendrocytes in exhibiting microtubules, prominent Golgi and short cell processes; pericellular lamination of cell processes, a characteristic of oligodendroglia, was noted in only one tumor. In two cases, OLC with astrocytic features were seen to contain small numbers of intermediate filaments. In four cases, a few OLC resembled immature neurons with scant dense-core granules or synapses.

This study confirms the glioneuronal nature of DNT, a lesion composed of heterogeneous cells, many resembling oligodendrocytes and a few showing early astrocytic and neuronal differentiation. Although their relation to OLC is unclear, the presence and peculiar distribution of mature neurons is nonetheless an integral diagnostic feature of the lesion.


Dysembryoplastic neuroepithelial tumor: an immunohistochemical study with myelin oligodendrocyte glycoprotein.

Gyure KA, Sandberg GD, Prayson RA, Morrison AL, Armstrong RC, Wong K.

Armed Forces Institute of Pathology, Washington, DC 20306, USA.

Arch Pathol Lab Med 2000 Jan;124(1):123-6 Abstract quote

CONTEXT: The dysembryoplastic neuroepithelial tumor (DNT) is an uncommon lesion characterized by a heterogeneous population of neurons, astrocytes, and oligodendroglia-like cells (OLCs). The basic nature of the DNT and its constituent cells, particularly the OLCs, remains unresolved; some authors favor a neuronal origin, and others propose a glial or mixed origin for these cells.

DESIGN: We examined 11 DNTs with antibodies to myelin oligodendrocyte glycoprotein, a marker of mature oligodendrocytes.

RESULTS: All DNTs studied (7 from males, 4 from females; age range of patients, 2-37 years) were composed of varying proportions of neurons, astrocytes, and OLCs. Membrane or cytoplasmic immunoreactivity for myelin oligodendrocyte glycoprotein was found in many OLCs in 9 of 11 cases. The number of myelin oligodendrocyte glycoprotein-positive OLCs was variable: >75% of the OLCs were positive in 5 cases, 25% to 75% of the OLCs were positive in 2 cases, and <25% of the OLCs were positive in 2 cases.

CONCLUSION: These findings suggest that many of the OLCs represent mature oligodendrocytes and support the notion that DNTs are heterogenous lesions composed of multiple, mature cell types.

MIB1  


Dysembryoplastic neuroepithelial tumor: a clinicopathologic and immunohistochemical study of 11 tumors including MIB1 immunoreactivity.

Prayson RA, Morris HH, Estes ML, Comair YG.

Department of Anatomic Pathology, Cleveland Clinic Foundation, OH 44195, USA.

 

Clin Neuropathol 1996 Jan-Feb;15(1):47-53 Abstract quote

The dysembryoplastic neuroepithelial tumor (DNT) is a rare, recently recognized neoplasm, characterized by a mixed glial-neuronal cell proliferation.

We studied 11 cases of DNT including 6 males and 5 females (age range 2.1-39.4 years, mean 13.8 years). All patients presented with chronic epilepsy of 4.8 years mean duration. Nine tumors were located in the temporal lobe and 2 in the frontal lobe. Four tumors were located on the right side and 7 on the left. All tumors were characterized by a predominant oligodendrocyte-like cell component with intermixed normal appearing neurons and astrocytes. All were focally microcystic and 7 of 9 evaluable tumors were multinodular. Other observed histologic features included a focal arcuate vascular pattern in 7 tumors, calcification in 4 tumors, and a rare mitotic figure in 2 tumors. Necrosis and vascular hyperplasia were not observed in any of the tumors. Cortical architectural disorganization (cortical dysplasia) was observed in 9 of 10 evaluable cases. MIB1 (a marker of cellular proliferation) immunostaining was performed in all 11 tumors and MIB1 indices (number of positive tumor cells/100 tumor cells counted) ranged from 0-0.6 (mean 0.2). Four patients required at least 1 additional surgical procedure for tumor recurrence, related to an incomplete initial excision 2.1-4.4 years after their initial operation. All patients are seizure-free at their last follow-up. DNTs are low grade neoplasms which typically present with chronic epilepsy, are most frequently located in the temporal lobe, and occur most frequently in pediatric patients.

Their appearance and association with cortical dysplasia suggest a maldevelopmental origin. The generally slow growth and relatively benign nature of DNT is reflected by their low MIB1 index.

ELECTRON MICROSCOPY  


Dysembryoplastic neuroepithelial tumor (DNT): an ultrastructural study of six cases.

Kordek R, Biernat W, Zakrzewski K, Polis L, Liberski PP.

Department of Molecular Biology, Polish Mother Memorial Hospital, Lodz.

Folia Neuropathol 1999;37(3):167-70 Abstract quote

We report six cases od DNT with a detailed ultrastructural characteristics. The patient age ranged from 7 to 16 years (mean 12), the location was temporal in three cases and frontal, temporooccipital and parietooccipital in each of one remaining cases.

The predominant clinical feature in each case was history of episodes of intractable seizures. Histopathologically, the neoplasms were multinodular, each nodule was well-circumscribed and was composed of glioneuronal elements embedded in the variable amount of myxoid matrix. The oligodendroglial-like cells (OLC) predominated in the nodules with some accompanying mature neurons. The nodules were frequently surrounded by small calcifications which could be found also within the tumors. OLCs were immunoreactive for S-100 protein and neurons had the expression of synaptophysin and neurofilament proteins.

Ultrastructurally, each tumor consisted of three major elements: neoplastic cells (OLC), elongated processes forming neuropil-like structure and expanded "mucoid" extracellular space: the latter gave an impression of cellular elements floating within it. Neoplastic cells had round, oval or elongated nuclei, no discernible nucleoli and a relatively narrow rim of the cytoplasm. Some nuclei were irregular and invaginated and pseudoinclusions were observed; a part of cytoplasm sequestered within pseudoinclusions often appeared degenerated with large blabs and electron-lucent vesicles, some of these contained in turn semicircular profiles of unknown significance. The second element consisted of innumerable cellular processes. Some of these were elongated and formed stacks connected by symmetrical symmetric or asymmetric adhesive plaque junctions. The others had shorter "neck" containing microtubules, these extended into bullous extensions.

Dense-cored vesicles were occasionally observed, in both cytoplasm of neoplastic cells and within processes. In one cell, cross-sectioned annulate lamellae were found. In cytoplasm of a few cells, unusual inclusions reminiscent ribosome-lamellae complexes were observed. These were cylindrical resembling "laboratory tubes" with a cone-like endings. At higher power, walls of the "tubes" resolved into layered structures composed of several laminae; between laminae, ribosome-like structures were visible.

 

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES
GENERAL


Dysembryoplastic neuroepithelial tumor.

Prayson RA, Estes ML.

Department of Pathology, Cleveland Clinic Foundation, Ohio 44195-5138.

Am J Clin Pathol 1992 Mar;97(3):398-401 Abstract quote

Dysembryoplastic neuroepithelial tumor is a recently described but rare tumor that occurs in children and characterized by long-standing, intractable partial complex seizures.

Due to a paucity of literature on this condition and its heterogeneous cellular composition, dysembryoplastic neuroepithelial tumors can present difficulties in diagnosis. The authors describe two cases of dysembryoplastic neuroepithelial tumor occurring in young patients (ages 8 and 19 years). Both tumors were located in the temporal lobe. Temporal lobectomy with excision of mesial structures resulted in resolution of the seizures.

Differential diagnosis includes oligodendrogliomas, mixed gliomas, and gangliogliomas. Features of the dysembryoplastic neuroepithelial tumor that are useful in making the distinction include a multinodular and multicystic appearance, the presence of both neuronal and glial (oligodendrocytic and astrocytic) components with little if any cytologic atypia, the presence of accompanying cortical dysplasia, and the lack of an arcuate vascular pattern. Because dysembryoplastic neuroepithelial tumors are curable by excision, the recognition and correct diagnosis of this tumor is important.

OLIGODENDROGLIOMA  


Dysembryoplastic neuroepithelial tumor. A tumor with small neuronal cells resembling oligodendroglioma.

Leung SY, Gwi E, Ng HK, Fung CF, Yam KY.

Department of Pathology, Queen Mary Hospital, University of Hong Kong.

Am J Surg Pathol 1994 Jun;18(6):604-14 Abstract quote

Dysembryoplastic neuroepithelial tumor (DNT) is a clinicopathologically unique group of tumors, mostly located in the temporal lobe, associated with intractable complex partial seizure in young patients.

We report two unusual cases with multifocal involvement of diverse sites in the central nervous system. Case 1 is that of a 50-year-old man with 9-year history of grand mal seizures, who died of acute myocardial infarction. Case 2 is that of a 10-year-old girl with intractable complex partial seizures and behavioral disorder. Postmortem examination in case 1 showed multifocal tumor in the left temporal lobe, third ventricle, and basal ganglia. Magnetic resonance imaging in case 2 showed tumor in the right temporal lobe, both thalami, right cerebellar hemisphere, and pons. Histologically, both tumors were characterized by a multinodular appearance with a predominant component of alveolar arrangement of oligodendroglial-like cells around delicate capillaries, with mucoid matrix containing floating ganglion cells. There were also astrocytic nodules resembling pilocytic astrocytoma in case 1, and a gangliocytoma-like area merging with surrounding cortical dysplasia in case 2.

Ultrastructural examination showed ganglionic differentiation in the oligodendroglial-like cells in case 2. They possessed dense core neurosecretory granules and many slender neuritic processes with microtubules arranged in parallel and terminating in synaptic junctions. The periventricularly located tumor with nodular extension to the periphery suggests an origin from subependymal germinal matrix with nests of primitive neuroblasts arrested in their embryonal migration. DNTs are related to ganglioglioma based on their common location and clinical behavior and on the presence of both ganglionic and astrocytic cells. They are also related to pilocytic astrocytoma by morphological and behavioral similarity. Together with cerebral neuroblastoma and central neurocytoma, they form a spectrum of tumors harboring small neuronal cells. The differentiation of DNT from oligodendroglioma is important so as to avoid unnecessarily aggressive therapy.

 

PROGNOSIS AND TREATMENT CHARACTERIZATION
Prognostic Factors  


Malignant transformation of a dysembryoplastic neuroepithelial tumor. Case report.

Hammond RR, Duggal N, Woulfe JM, Girvin JP.

Department of Pathology, London Health Sciences Centre and University of Western Ontario, Canada.

J Neurosurg 2000 Apr;92(4):722-5 Abstract quote

A 29-year-old man presented in 1984 with a recent onset of partial seizures marked by speech arrest. Electroencephalography identified a left frontotemporal dysrhythmia. Computerized tomography (CT) scanning revealed a superficial hypodense nonenhancing lesion in the midleft frontal convexity, with some remodeling of the overlying skull. The patient was transferred to the London Health Sciences Centre for subtotal resection of what was diagnosed as a "fibrillary astrocytoma (microcystic)." He received no chemotherapy or radiation therapy and remained well for 11 years. The patient presented again in late 1995 with progressive seizure activity. Both CT and magnetic resonance imaging demonstrated a recurrent enhancing partly cystic lesion. A Grade IV astrocytoma was resected, and within the malignant tumor was a superficial area reminiscent of a dysembryoplastic neuroepithelial tumor (DNT).

Data on the lesion that had been resected in 1984 were reviewed, and in retrospect the lesion was identified as a DNT of the complex form. It was bordered by cortical dysplasia and contained glial nodules, in addition to the specific glioneuronal element. The glial nodules were significant for moderate pleomorphism and rare mitotic figures. The Ki67 labeling index averaged 0.3% in the glial nodules and up to 4% focally. Cells were rarely Ki67 positive within the glioneuronal component. This case is the first documented example of malignant transformation of a DNT. It serves as a warning of the potential for malignant transformation in this entity, which has been traditionally accepted as benign.

This warning may be especially warranted when confronted with complex forms of DNT. The completeness of resection in the benign state is of paramount importance.

SURVIVAL

Behaves in benign fashion

Seven patients underwent gross total resection and two underwent subtotal resection. No patients received adjuvant chemotherapy or radiotherapy.

On follow-up (n = 6; median, 14 months), all tumors had either not recurred or were radiologically stable.

TREATMENT  


Dysembryoplastic neuroepithelial tumor: a surgically curable tumor of young patients with intractable partial seizures. Report of thirty-nine cases.

Daumas-Duport C, Scheithauer BW, Chodkiewicz JP, Laws ER Jr, Vedrenne C.

Department of Pathology, Hopital Sainte Anne, Paris, France.

Neurosurgery 1988 Nov;23(5):545-56 Abstract quote

This report concerns the clinicopathological features of 39 cases of a morphologically unique and surgically curable group of neuroepithelial tumors associated with medically intractable partial complex seizures.

All were supratentorial and characterized by intracortical location, multinodular architecture, and heterogeneity in cellular composition. The constituent cells included astrocytes, oligodendrocytes, and neurons. Because neuronal atypia was often inapparent, the tumors superficially resembled mixed oligoastrocytomas. The term "dysembryoplastic neuroepithelial tumor" (DNT) is proposed for these distinctive lesions, the clinicopathological features of which suggest a dysembryoplastic origin.

With the exception of the occurrence of headaches in 2 patients, partial complex seizures were the exclusive symptom. Age at onset of symptoms ranged from 1 to 19 years (mean 9 years). In addition to the chronic nature of the seizures (range, 2 to 18 years; mean, 9 years), one-third of the patients showed radiological features, such as focal cranial deformity, indicating that the tumors had an early onset and were of long standing. In most cases, computed tomography showed a "pseudocystic," well-demarcated, low density appearance associated in some cases with focal contrast enhancement (18%) or calcific hyperdensity (23%). The tumor involved the temporal lobe in 24 patients (62%), the frontal lobe in 12 (31%), and the parietal and/or occipital lobe in 3 cases. Although tumor removal was considered incomplete or subtotal in 17 patients (44%), long term follow-up (range, 1 to 18 years; mean, 9 years) showed neither clinical nor radiological evidence of recurrence in any patient. Comparison of the survival data of the 13 subjects who had undergone postoperative radiotherapy with 26 who had not indicated that radiation therapy was of no obvious benefit.

he identification of DNT has therapeutic and prognostic implications because aggressive therapy can be avoided, thus sparing these young patients the deleterious long term effects of radio- or chemotherapy.

Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.
Robbins Pathologic Basis of Disease. Sixth Edition. WB Saunders 1999.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.


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