Different pattern of expression of nestin in the non-specific form of dysembryoplastic neuroepithelial tumors compared to the simple and complex forms

Dysembryoplastic Neuroepithelial Tumors

Dysembryoplastic neuroepithelial tumor (DNT) is a benign glioneuronal neoplasm that most commonly occurs in children and young adults and may present with medically intractable, chronic seizures. Radiologically, this tumor is characterized by a cortical topography and lack of mass effect or perilesional edema. Partial complex seizures are the most common presentation. Three histologic subtypes of DNTs have been described. Histologically, the recognition of a unique, specific glioneuronal element in brain tumor samples from patients with medically intractable, chronic epilepsy serves as a diagnostic feature for complex or simple DNT types. However, nonspecific DNT has diagnostic difficulty because its histology is indistinguishable from conventional gliomas and because a specific glioneuronal element and/or multinodularity are absent. This review will focus on the clinical, radiographic, histopathological, and immunohistochemical features as well as the molecular genetics of all three variants of DNTs. The histological and cytological differential diagnoses for this lesion, especially the nonspecific variant, will be discussed.

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.

Diffuse form of dysembryoplastic neuroepithelial tumour: the histological and immunohistochemical features of a distinct entity showing transition to dysembryoplastic neuroepithelial tumour and ganglioglioma

AIMS

A diffuse variant of dysembryoplastic neuroepithelial tumour (dDNT) has previously been described, which although composed of oligodendroglia-like cells (OLC), astrocytes and mature neurones, lacks the multinodularity and 'specific component' of typical DNT. The dDNT poses a significant challenge to the neuropathologist. This study was undertaken to further characterize the histological and immunohistochemical features of dDNT.

MATERIALS AND METHODS

Review of our archived material from epilepsy surgery identified 16 cases, in which features of dDNT predominated. Their histological and immunohistochemical features, including CD34 and nestin immunohistochemistry, were analysed.

RESULTS

Seven cases had the characteristics of pure dDNT. A further two cases of dDNT showed extension into the white matter with occasional dysplastic neurones. Two additional cases had similar features but with the presence of either single, or multiple small nodular clusters of OLC, in keeping with transition to classical DNT. Five cases showed ganglioglioma-like areas, of which three cases had micronodule formation but with predominant dDNT pattern. In all the cases the dDNT areas showed strong CD34 and less intense nestin immunoreactivity and microglial activation highlighting the full extent of the lesions. There was variable overlap between CD34 and nestin positivity within the micronodular and/or ganglioglioma-like areas.

CONCLUSIONS

Immunoreactivity for CD34 and nestin characterizes the dDNT and helps to distinguish it from other lesions associated with epilepsy. Histological evidence indicative of transition of dDNT to other forms of DNT and ganglioglioma suggests that dDNT might be an early histogenetic form of these glioneuronal tumours.

CD34 and microtubule-associated protein 2 expression in dysembryoplastic neuroepithelial tumours with an emphasis on dual expression in non-specific types

AIMS

 Three histological variants of dysembryoplastic neuroepithelial tumour (DNT) have been described, namely, simple, complex and non-specific. However, the concept of non-specific variants of DNT remains controversial, because they cannot be accurately distinguished by histological findings alone from ordinary gliomas. The aim was to characterize further the non-specific histological forms of DNT.

METHODS AND RESULTS

Forty-one DNTs classified as three histological forms were investigated with CD34 and microtubule-associated protein 2 (MAP2) immunohistochemistry. CD34 immunoreactivity was more frequently observed in non-specific DNT types (16/18 cases; 88.9%) than in classic types (6/23 cases; 26.1%) (P < 0.001). Peritumoral CD34 expression of non-neoplastic cells was significantly associated with CD34-positive tumours (20/22 cases; 90.9%) than with CD34-negative tumours (3/19 cases; 15.8%) (P < 0.001). MAP2 positivity in oligodendroglia-like cells or glial elements was significantly different between classic types and non-specific types (P = 0.025). CD34 and MAP2 immunoreactivities were significantly more frequent in non-specific types (83.3%) than in simple (10%) and complex forms (30.8%) (P < 0.001).

CONCLUSIONS

Non-specific DNTs are glioneuronal tumours that have a heterogeneous population of cells with more immature neuronal and glial phenotypes. Furthermore, with regard to practical implications, combined analysis of CD34 and MAP2 is useful in distinguishing DNTs from particularly diagnostically challenging mimics.

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.