Histological heterogeneity of dysembryoplastic neuroepithelial tumour: identification and differential diagnosis in a series of 74 cases
- 1 April 1999
- journal article
- research article
- Published by Wiley in Histopathology
- Vol. 34 (4) , 342-356
- https://doi.org/10.1046/j.1365-2559.1999.00576.x
Abstract
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. 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. 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.Keywords
This publication has 24 references indexed in Scilit:
- Dysembryoplastic neuroepithelial tumors in two children with neurofibromatosis type 1Acta Neuropathologica, 1995
- Dysembryoplastic neuroepithelial tumour of the cerebellumActa Neuropathologica, 1995
- Dysembryoplastic Neuroepithelial TumorNeurosurgery, 1995
- Dysembryoplastic neuroepithelial tumour Features in 16 patientsBrain, 1994
- Dysembryoplastic Neuroepithelial TumorThe American Journal of Surgical Pathology, 1994
- Neuropathological findings in 224 patients with temporal lobe epilepsyActa Neuropathologica, 1993
- Surgical Pathology of Temporal Lobe Epilepsy. Experience with 216 CasesJournal of Neuropathology and Experimental Neurology, 1993
- Control of temporal lobe epilepsy following en bloc resection of low-grade tumorsJournal of Neurosurgery, 1993
- In situ analysis of cell kinetics in human brain tumorsActa Neuropathologica, 1989
- Dysembryoplastic Neuroepithelial Tumor: A Surgically Curable Tumor of Young Patients with Intractable Partial SeizuresNeurosurgery, 1988