1/4. Atypical extraventricular neurocytoma with oligodendroglioma-like spread and an unusual pattern of chromosome 1p and 19q loss.An insular cortex tumor in a 54-year-old woman showed unequivocal neurocytic features, including open nuclei, distinct nucleoli, and strong synaptophysin immunoreactivity. Ultrastructurally, there were neuritic-type processes with microtubules and hillock-like attachments, and there were dense-core granules. Atypical features were mitotic activity, prominent vasculature, and small foci of necrosis. Peripherally, there was oligodendroglia-like histology with single-cell infiltration of white matter and perineuronal spread in cortex. fluorescence in situ hybridization analysis with chromosome 1 and 19 probes showed 3 copies of 1q and 2 copies of 1p and showed 2 copies of 19q and 4 copies of 19p. This yielded a 1p-19q loss of heterozygosity pattern similar to that seen in oligodendrogliomas, although the actual chromosomal abnormality is distinct. This tumor, best classified as an atypical neurocytoma with oligodendroglia-like spread, supports suggestions of a close histogenic relationship between oligodendroglial and neurocytic tumors. This case also illustrates the limitations of relying exclusively on loss of heterozygosity analysis for tumor classification.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/4. Comparative genetic analysis of metachronous anaplastic oligoastrocytomas with extended recurrence-free interval.Two metachronous anaplastic oligoastrocytomas with different cerebral locations were analyzed in a 51-year-old patient with an extended recurrence-free interval of 6 years and an a long survival of 9 years. Remarkably, the patient had not undergone adjuvant chemotherapy. Different cytogenetic and molecular techniques were performed including comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), allelic loss analysis, sequencing of p53, p16(INK4a)/CDKN2A and p14(ARF), EGFRamplification studies, investigation of the dna mismatch repair system as well as tumor clonality. Using CGH and FISH a profile of low accumulation of cytogenetic aberrations was found in the second tumor, with no significant increase in the percentage of hyperdiploid nuclei. Microsatellite analysis showed a common pattern of allelic losses at 1p36, 19q13 and 9p21. Both specimens were also similar in that they retained heterozygosity at 10q23-q24 and 13q14 and that they harbor neither EGFR amplification nor mutations of p53, p16(INK4a)/CDKN2A or p14(ARF). The only further alteration in the second tumor was an allelic loss at p53. The X-chromosome inactivation (HUMARA) analysis revealed a polyclonal pattern in both samples. Our data strongly suggest that the second anaplastic oligoastrocytoma developed as a distant relapse of the first tumor. Whether the paucity of accumulation of the observed genetic alterations might be associated with the unusually extended relapse-free time of the patient remains to be elucidated.- - - - - - - - - - ranking = 2keywords = hybridization (Clic here for more details about this article) |
3/4. Identification of der(1;19)(q10;p10) in five oligodendrogliomas suggests mechanism of concurrent 1p and 19q loss.Deletions of portions of chromosomes 1p and 19q are closely associated with the oligodendroglioma histologic phenotype. In most cases, 1p and 19q are codeleted, yet the mechanism of dual loss is unexplained. We report 5 cases (world health organization grade III) in which metaphase cytogenetics identified a derivative chromosome consisting of what appears to be the whole arms of 1q and 19p forming a der(1;19)(q10;p10). metaphase fluorescent in situ hybridization (FISH) confirmed the derivative chromosome was composed of 1q and 19p material in 3 cases; in 2 cases with few metaphases, FISH confirmed 19p material on the derivative chromosome. In all cases, interphase FISH showed net loss of 1p and 19q in 77% to 92% of cells, and microsatellite studies were consistent with 1p and 19q loss. We hypothesize the following: occurrence of a balanced whole-arm translocation between chromosomes 1 and 19 forming 2 derivative chromosomes, one composed of 1q and 19p, the other of 1p and 19q. Subsequent loss of the der(1;19)(p10;q10) then results in the simultaneous 1p and 19q loss observed in oligodendroglioma with retention of the der(1;19)(q10;p10) seen in these cases.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
4/4. Primary disseminated leptomeningeal oligodendroglioma with 1p deletion. Case report.The authors report the case of a 2-year-old boy with a primary, diffuse leptomeningeal oligodendroglioma in which the deletion of chromosome arm lp was identified by performing a fluorescence in situ hybridization (FISH) analysis. This previously healthy child initially presented with malaise, anorexia, nausea, vomiting, and macrocephaly. Imaging studies confirmed the presence of hydrocephalus, and a ventriculoperitoneal shunt was placed. The postoperative course was complicated by emesis, continued weight loss, and numerous seizurelike episodes. A contrast-enhanced magnetic resonance imaging study performed approximately 10 weeks postoperatively showed diffuse leptomeningeal thickening and enhancement without evidence of an intraparenchymal mass lesion. A right frontal lobe brain biopsy revealed a hypercellular proliferation of small oligodendroglioma-like cells, which occupied the leptomeninges diffusely and spared the underlying cortical gray matter. The tumor cells displayed prominent perinuclear clearing and had evenly spaced, uniformly round nuclei. Occasional mitotic figures were observed. Background vessels were thin and delicate, and there was no evidence of necrosis. The tumor cells showed strong immunoreactivity for S100 protein; the results of immunohistochemical staining were negative for glial fibrillary acidic protein, vimentin, epithelial membrane antigen, NeuN, and synaptophysin. The deletion of lp was demonstrated by FISH analysis; lq, 19p, and 19q were intact. This appears to be the first reported case of a primary diffuse leptomeningeal oligodendroglioma in which a lp deletion was identified.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |