p53 mutations are the most frequently detected genetic alterations of gliomas, appearing in a similar proportion of low and high grade astrocytomas, while the amplification of epidermal growth factor receptor (EGFR) gene appears mainly in glioblastomas. Thus, these changes seem to delineate two subgroups of high grade astrocytomas: those originating from preexistent low grade astrocytomas and those originating de novo. Paraffin-embedded surgical specimens from 56 human astrocytomas (8 pilocytic (I.) astrocytomas, 9 low grade (II.) fibrillary astrocytomas, 9 high grade (III.) anaplastic astrocytomas and 30 glioblastomas) were analyzed immunohistochemically for the presence of p53 protein and EGFR. Approximately 41% of all cases were p53-protein-positive while 23% were EGFR-positive. Five cases (8.9%) were double-positive for p53 protein and EGFR. The p53-immunopositive nuclei were revealed in 16 cases (53.3%) of glioblastomas, 3 cases (33.3%) of high grade and 4 cases (44.4%) of low grade astrocytomas. None of pilocytic tumors was p53-positive. EGFR immunopositivity increased with the grade of malignancy (11.1%, 22.2% and 33.3%). Double EGFR-p53-positive cases occuried in similar proportions in all grades (approximately 10%) and did not show different survival rate. There were no differences between average age of patients with only-p53-positive, p53-negative (pilocytic tumors excluded) and only-EGFR-positive tumors.
A 32-year-old man with rapidly progressive dementia, pyramidal signs, myoclonic jerks and dystonic movements died following brain biopsy. neuropathological examination revealed minimal neuronal loss accompanied by mild spongiform change and astrocytic reaction. Numerous plaques and neurofibrillary tangles composed of paired helical filaments dominated the ultrastructural picture. This patient had features of both Creutzfeldt-Jakob disease and Alzheimer's disease, providing additional support for the existence of an overlap between these disorders.
We report here ultrastructural and immunohistochemical studies of neuroblastic differentiation in the retrospective (n = 17) and prospective (n = 26) series of primitive neuroectodermal tumors (PNETs). By electron microscopy, neuritelike structures containing parallel-oriented microtubules, adhesive plaque junctions, and pleomorphic dense-core vesicles were found in the majority of tumor specimens while synaptic specializations were very rare. By immunohistochemistry, synaptophysin appeared to be the most reliable marker for neuroblastic differentiation present in the most reliable marker for neuroblastic differentiation present in the majority of tumors, while 200 kDa neurofilament protein was immunovisualized in a lower proportion of tumors. Glial fibrillary acidic protein (GFAP) was expressed in both reactive astrocytes and in a small proportion of otherwise typical neoplastic cells. We conclude that the majority of PNETs revealed diverse differentiation and that electron microscopy is still the most reliable tool for its detection followed by immunohistochemistry for synaptophysin.
We report a case of a 24-year-old woman with left temporal pleomorphic xanthoastrocytoma (PXA) with atypical neuronal cells. Many neoplastic cells, otherwise typical of PXA, expressed glial fibrillary acidic protein, while neuronal cells with marked atypia were immunopositive for synaptophysin and neurofilament protein. This report supports a notion that PXA, like other astrocytic tumors, may have its gangliogliomatous counterpart.
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