Multifocal dysembryoplastic neuroepithelial tumor with signs of atypia after regrowth

A Constellation of Atypical Findings in a Nine-Year-Old Child With Dysembryoplastic Neuroepithelial Tumors: A Case Report and Review of the Literature

Dysembryoplastic neuroepithelial tumors (DNETs) are rare, generally benign, mixed neuronal-glial neoplasms occurring most often between 10 and 14 years of age. These lesions are classically cortically based and solitary, found preferentially in the temporal lobe, and most commonly present with seizures. On magnetic resonance imaging (MRI), these lesions are generally cystic and have variable contrast enhancement, which, when present, often involves the periphery. Rarely, lesions followed radiographically may demonstrate delayed contrast enhancement. Here, we present a case of multifocal DNETs involving the cerebellum that demonstrated delayed contrast enhancement. In addition, these occurred in a patient with Noonan syndrome (NS), a “RASopathy” disorder associated with low-grade glial and glioneuronal tumors. We present a summary of all previously reported cases of cerebellar DNETs. Our patient was successfully treated surgically and is doing well clinically, now one year status post his last procedure, and is being closely monitored with serial MRIs for progression. Gross total resection is often curative without adjuvant therapy for most DNETs. Our case emphasizes the importance of radiographic surveillance, as multifocality and recurrence may necessitate more than one procedure. Lastly, clinicians should be suspicious for DNETs and other low-grade glial tumors when treating patients with NS, acknowledging their predisposition for multifocal involvement and atypical presentations.

Dysembryoplastic neuroepithelial tumors: A single-institutional series with special reference to glutamine synthetase expression

Dysembryoplastic neuroepithelial tumors (DNT) is a benign (World Health Organisation, WHO, grade I) glioneuronal tumor and it represent one of the most frequent neoplasm in patient affected by seizures. The epileptic neuronal activity can be determined by abnormal synchronization, excessive glutamate excitation and\or inadequate GABA inhibition. Increasing evidence suggests that the astrocytes might be involved in this process even if neurons play a relevant role. In particular astrocytes promote the clearance of glutamate, a potent excitatory neurotransmitter of the central nervous system. Indeed, elevated concentrations of extracellular glutamate may determine iper-excitability and seizures as well as other neurological disorders. So, astrocytes, converting glutamate into glutamine via the enzyme glutamine synthetase (GS), could play a protective anti-seizures role. In the present study, we analyzed the immunohistochemical expression of GS in 20 DNTs specimens documenting a constant immunoistochemical expression of GS in astrocytes of the lesional tissue and of the cerebral cortex.

Dysembryoplastic Neuroepithelial Tumors: What You Need to Know

OBJECTIVE

An updated and comprehensive review on dysembryoplastic neuroepithelial tumor (DNET) focusing on differential diagnosis, atypical presentation, seizure outcome, and risk of malignant transformation.

METHODS

A PubMed/MEDLINE-based literature search has been performed using "dysembryoplastic neuroepithelial tumor" as a keyword. Two treated cases characterized by an atypical presentation have been reviewed.

RESULTS

Of 1162 articles, 200 relevant studies have been selected. DNET is a benign mixed neuronal-glial tumor causing drug-resistant epilepsy primarily in children and young adults. The typical radiological pattern is a magnetic resonance imaging (MRI) T1-hypointense, T2-, and fluid-attenuated inversion-recovery hyperintense multicystic lesion involving the cerebral cortex with no edema. Contrast enhancement may be present and a focal cortical dysplasia is commonly associated with it. MRI diffusion, perfusion, and spectroscopy have a paramount role in the differential diagnosis. The "specific glioneuronal elements" are pathognomonic. They are positive for S100 protein, synaptofisin, neuronal nuclei, oligodendrocyte transcription factor, neurite outgrowth inhibitor, and microtubule-associated protein 2, but negative for glial fibrillary acidic protein. As opposed to v-myb avian myeloblastosis viral oncogene homolog, isocitrate dehydrogenase-1/isocitrate dehydrogenase-2 mutation and codeletion 1p-19q, fibroblast growth factor receptor 1 and BRAF V600E mutations are present. The effectiveness of surgery on seizure outcome has been established. Rare malignant transformations have been reported, especially in extra-temporal and complex forms.

CONCLUSIONS

Advanced MRI techniques are fundamental in the differential diagnosis for DNET versus other low-grade gliomas. Immuno-phenotype assessment and search for fibroblast growth factor receptor 1 and BRAF V600E mutations limit the risk of misdiagnoses. A gross total tumor removal is generally associated with a seizure-free outcome. Recurrences and malignant transformations may rarely follow, legitimizing MRI surveillance in cases of subtotal tumor resection.

Coexistent dysembryoplastic neuroepithelial tumour and pilocytic astrocytoma

Dysembryoplastic neuroepithelial tumour (DNET) is an uncommon mixed glioneuronal tumour. DNET is classified as Grade I neoplasm in revised World Health Organization classification of tumors of the nervous system. DNET is commonly seen in the temporal lobe of children and young adults with features of pharmacoresistant complex partial seizures. Tumors arising in association with DNETs are rare. Only two cases of pilocytic astrocytoma (PA) arising in DNETs are reported. Surgical excision is the only successful management with favourable prognosis. The development of recurrence and malignancy after subtotal or even after complete excision challenges the premise of stability and highlights the importance of close clinical follow up. Here, a case of DNET with area of PA is described which helps in understanding the pathogenesis and biological behavior of DNET.

Atypical Teratoid Rhabdoid Tumor Diagnosis after Partial Resection of Dysembryoplastic Neuroepithelial Tumor: Case Report and Review of the Literature

Dysembryoplastic neuroepithelial tumors (DNETs) are generally considered benign, slow-growing epilepsy-associated lesions. While rare cases of malignant transformation of DNET to high-grade glial tumors have been reported, to our knowledge there have been no reports of transformation/emergence of DNET to atypical teratoid rhabdoid tumor (AT/RT), a highly aggressive embryonal brain tumor. Here, we report the case of an 8-year-old boy who presented with an incidental finding of a small right insular lesion which grew slowly over 3 years. The patient first underwent surgery with subtotal tumor resection at age 11. Pathology was consistent with DNET. Following surgery, further tumor growth was evident, requiring fractionated radiotherapy and eventually chemotherapy, but continued tumor growth was witnessed. Three years after radiation, imaging showed dramatic further tumor growth, and the patient underwent a second debulking surgery. The pathology revealed a malignant tumor with BAF47-negative cells, suggestive of AT/RT. This report adds to our knowledge about the poorly understood behavior and natural history of DNETs and emphasizes the importance of lifelong clinical and neuroimaging follow-up of these lesions.

Occurrence of DNET and other brain tumors in Noonan syndrome warrants caution with growth hormone therapy

Noonan syndrome (NS) is an autosomal dominant developmental disorder caused by mutations in the RAS-MAPK signaling pathway that is well known for its relationship with oncogenesis. An 8.1-fold increased risk of cancer in Noonan syndrome has been reported, including childhood leukemia and solid tumors. The same study found a patient with a dysembryoplastic neuroepithelial tumor (DNET) and suggested that DNET tumors are associated with NS. Herein we report an 8-year-old boy with genetically confirmed NS and a DNET. Literature review identified eight other reports, supporting the association between NS and DNETs. The review also ascertained 13 non-DNET brain tumors in individuals with NS, bringing to 22 the total number of NS patients with brain tumors. Tumor growth while receiving growth hormone (GH) occurred in our patient and one other patient. It is unknown whether the development or progression of tumors is augmented by GH therapy, however there is concern based on epidemiological, animal and in vitro studies. This issue was addressed in a 2015 Pediatric Endocrine Society report noting there is not enough data available to assess the safety of GH therapy in children with neoplasia-predisposition syndromes. The authors recommend that GH use in children with such disorders, including NS, be undertaken with appropriate surveillance for malignancies. Our case report and literature review underscore the association of NS with CNS tumors, particularly DNET, and call attention to the recommendation that clinicians treating NS patients with GH do so with awareness of the possibility of increased neoplasia risk.

Dysembryoplastic neuroepithelial tumor: a clinical, neuroradiological, and pathological study of 15 cases

Dysembryoplastic neuroepithelial tumors are rare, surgically curable, neuronal-glial neoplasms affecting young patients with intractable epilepsy. Its recognition is needed to avoid unnecessary adjuvant therapy. The authors reviewed the records of 15 patients with dysembryoplastic neuroepithelial tumors who underwent epilepsy surgery using intraoperative electrocorticography monitoring, including 8 males and 7 females (mean age, 15.8 years). Neuroimaging showed a predominantly intracortical location, the presence of septations, a triangular pattern of distribution, a lack of contrast enhancement, and an absence of peritumoral edema. Eleven cases were classified as complex type, 3 as simple type, and 1 as "nonspecific" type. Associated cortical dysplasia was found in 5 cases and leptomeningeal involvement in 1 case. Its immunophenotype suggested a pluripotential neuroepithelial origin. The mean follow-up was 37.5 months; 2 patients had tumor recurrence. Although they are generally benign neoplasms, recurrences sometimes occur. Complete resection of the tumor with the epileptogenic zone is important for a favorable outcome.

Recurrence and histological evolution of dysembryoplastic neuroepithelial tumor: A case report and review of the literature

Studies of recurrent dysembryoplastic neuroepithelial tumors (DNTs) are distinctly rare. The present study reports the case of a 15-year-old female with a temporal lobe DNT, which recurred and transformed into an astrocytoma (WHO grade II) five years after an initial gross total resection (GTR). Furthermore, all the previous studies on recurrent DNT are reviewed. Although the majority of DNT cases demonstrate benign behavior, recurrent DNTs have been observed following a GTR of the tumor. Patients do not appear to benefit from post-operative adjuvant therapy, and inappropriate radiotherapy or chemotherapy may result in tumor recurrence or malignant transformation. The prognosis is favorable if a GTR of the recurrent tumor is achieved. The use of regular imaging examinations and the maintenance of a long-term follow-up is of importance following a tumor resection.

Dynamic changes in magnetic resonance imaging appearance of dysembryoplastic neuroepithelial tumor with or without malignant transformation

Dysembryoplastic neuroepithelial tumors (DNETs) have conventionally been regarded as benign and stable tumors and considered curable with surgery without adjunctive therapy. Recently, recurrent DNETs with or without malignant transformation have been described. The authors report 2 unusual cases of DNET: 1) an enlarging lesion that developed an enhancing component over the natural course of 4 years, and 2) a recurrent DNET that developed an enhancing component 10-11 years after gross-total resection. The patient in the first case was treated with subtotal resection and adjuvant radiochemotherapy; histological examination of the tumor led to the diagnosis of DNET, WHO Grade I, for the nonenhancing component and anaplastic oligodendroglioma, WHO Grade III, for the enhancing component. The patient in the second case was treated with repeat gross-total resection; the original tumor had been histologically diagnosed as DNET, and the nonenhancing and enhancing components of the recurrent tumor were diagnosed as simple and complex forms of DNET, respectively. These and previous reports suggest an aggressive subtype of DNETs. If follow-up MRI reveals progressive behavior, resection should be performed without delay. Additional radiochemotherapy is needed if the histological diagnosis demonstrates malignant transformation.

Long-term epilepsy-associated tumors

The term long-term epilepsy associated tumor (LEAT) encompasses lesions identified in patients investigated for long histories (often 2 years or more) of drug-resistant epilepsy. They are generally slowly growing, low grade, cortically based tumors, more often arising in younger age groups and in many cases exhibit neuronal in addition to glial differentiation. Gangliogliomas and dysembryoplastic neuroepithelial tumors predominate in this group. LEATs are further united by cyto-architectural changes that may be present in the adjacent cortex which have some similarities to developmental focal cortical dysplasias (FCD); these are now grouped as FCD type IIIb in the updated International League Against Epilepsy (ILAE) classification. In the majority of cases, surgical treatments are beneficial from both perspectives of managing the seizures and the tumor. However, in a minority, seizures may recur, tumors may show regrowth or recurrence, and rarely undergo anaplastic progression. Predicting and identifying tumors likely to behave less favorably are key objectives of the neuropathologist. With immunohistochemistry and modern molecular pathology, it is becoming increasingly possible to refine diagnostic groups. Despite this, some LEATs remain difficult to classify, particularly tumors with "non-specific" or diffuse growth patterns. Modification of LEAT classification is inevitable with the goal of unifying terminological criteria applied between centers for accurate clinico-pathological-molecular correlative data to emerge. Finally, establishing the epileptogenic components of LEAT, either within the lesion or perilesional cortex, will elucidate the cellular mechanisms of epileptogenesis, which in turn will guide optimal surgical management of these lesions.

One hundred and one dysembryoplastic neuroepithelial tumors: an adult epilepsy series with immunohistochemical, molecular genetic, and clinical correlations and a review of the literature

Simple and complex forms of dysembryoplastic neuroepithelial tumors (DNTs) are readily recognizable but forms with diffuse growth pattern, and hybrid tumors, that is, mixed DNT and ganglioglioma (DNT/GG), are more contentious entities. Rare DNTs have shown aggressive behavior. We reviewed cortical growth patterns, immunophenotype (including CD34, nestin and calbindin), genetic profile, and outcome in 101 DNT in adults. Simple (n = 18), complex (n = 31), diffuse (n = 35) DNT, and mixed DNT/GG (n = 17) showed no difference in age of onset, associated seizure type, or outcome (67.5% free from seizure; mean follow-up, 6 years). CD34 was seen in 61%, calbindin in 57%, and nestin in 86% of all DNT types; these markers were less common in simple DNT. Peritumoral cortical changes (Layer I hypercellularity [61%], satellite nodules [51.6%]) were frequent, but dyslamination (cortical dysplasia) was not identified. Molecular genetic abnormalities identified in 17 cases were IDH1 mutation (n = 3), 1p/19q loss (n = 10), isolated loss 9q (n = 2), and PTEN loss (n = 3), which were not associated with tumor type or location, higher cell proliferation, or distinguishing clinical features (mean age of epilepsy onset, 9 years; age at surgery = 31 years; 69% free from seizure); none had progression on magnetic resonance imaging (mean follow-up, 6 years). No single feature was predictive of seizure-free outcome, but there was a trend for better outcome in CD34-positive tumors (p = 0.07). One case has shown transformation to a higher grade. This study supports the existence of a range of subtypes of DNT some with overlapping features with ganglioglioma; molecular genetic abnormalities were not predictive of atypical behavior.

Multifocal dysembryoplastic neuroepithelial tumour with intradural spinal cord lipomas: report of a case

We report a case of temporal lobe epilepsy and incomplete Brown-Sequard syndrome of the thoracic cord. Computed tomography and magnetic resonance (MR) imaging showed multiple supratentorial masses with the classical radiological appearances of multifocal dysembryoplastic neuroepithelial tumour (DNET). Spinal MR imaging revealed intradural lipomas, not previously reported in association with multifocal DNET. Presentation and imaging findings are discussed along with classification and natural history of the tumour.

F-18 FDG-PET imaging of dysembryoplastic neuroepithelial tumor-like astrocytoma

Cerebral astrocytoma needs to be distinguished from dysembryoplastic neuroepithelial tumor (DNT) when a well-demarcated, cortically based and pseudo-cystic tumor with minimal mass effect is demonstrated on magnetic resonance imaging. We report an unusual case of DNT-like astrocytoma. 18F fluoro-deoxy-glucose (FDG) positron emission tomography showed a focal increase of FDG uptake in a deep part of the tumor. Histologic examination revealed predominantly microcystic change with oligodendrocyte-like cells, leading to a diagnosis of DNT. However, increased cellularity and nuclear atypia of astrocytes within the tumor were conspicuous as for DNT. Four years after excision, tumor recurrence was detected. FDG-positron emission tomography is useful for identifying the malignant potential of DNT-like astrocytoma.