Primary Rhabdomyosarcoma Mimicking a Small Cell Sarcoma of Bone: A Nude Mice Xenograft, Cytogenetic, and Molecular Approach

Small cell sarcomas of bone are difficult to classify and diagnose. The present case deals with such a tumor in which the original biopsy and the resected specimen, studied by histology before chemotherapy, provided no final information about its real nature. Thus several techniques were applied to discern its histogenesis and biology. Myogenin proved positive in isolated cells of the primary neoplasm but was extensively expressed in nude mice xenografts. Electron microscopy confirmed the existence of myofilaments. The cytogenetic analysis revealed a large number of chromo somal abnormalities, but not those found in the Ewing's/PNET (peripheral neuroectodermal tumor) family of tumors. This was confirmed by polymerase chain reaction (RT-PCR) wherein no EWS/Fli 1 or PAX3/FKHR gene rearrangements were detected. Based upon these studies, a rhabdomyosarcoma of bone was diagnosed. Clinically the neoplasm showed a highly aggressive behavior, causing death of the patient within 2 years after diagnosis.

Magnetic resonance microscopy at 14 Tesla and correlative histopathology of human brain tumor tissue

Magnetic Resonance Microscopy (MRM) can provide high microstructural detail in excised human lesions. Previous MRM images on some experimental models and a few human samples suggest the large potential of the technique. The aim of this study was the characterization of specific morphological features of human brain tumor samples by MRM and correlative histopathology. We performed MRM imaging and correlative histopathology in 19 meningioma and 11 glioma human brain tumor samples obtained at surgery. To our knowledge, this is the first MRM direct structural characterization of human brain tumor samples. MRM of brain tumor tissue provided images with 35 to 40 µm spatial resolution. The use of MRM to study human brain tumor samples provides new microstructural information on brain tumors for better classification and characterization. The correlation between MRM and histopathology images allowed the determination of image parameters for critical microstructures of the tumor, like collagen patterns, necrotic foci, calcifications and/or psammoma bodies, vascular distribution and hemorrhage among others. Therefore, MRM may help in interpreting the Clinical Magnetic Resonance images in terms of cell biology processes and tissue patterns. Finally, and most importantly for clinical diagnosis purposes, it provides three-dimensional information in intact samples which may help in selecting a preferential orientation for the histopathology slicing which contains most of the informative elements of the biopsy. Overall, the findings reported here provide a new and unique microstructural view of intact human brain tumor tissue. At this point, our approach and results allow the identification of specific tissue types and pathological features in unprocessed tumor samples.

Concurrent EGFR amplification and TP-53 mutation in glioblastomas

Glioblastoma multiforme is the most common and most aggressive of the primary brain tumors. The mean survival of patients is 10-12 months. Conventional therapy of surgery, radiation and chemotherapy is largely palliative. Cytogenetically, karyotypes of glioblastomas are very complex with trisomy 7 and monosomy 10 as the most frequent abnormalities. A genetic alteration that is significantly more frequent in primary than in secondary glioblastomas, the latter arising from preceding low-grade gliomas, is epidermal growth factor receptor gene (EGFR) amplification, whereas TP-53 mutations are significantly more frequent in low-grade gliomas and secondary glioblastomas derived there- from. We report the histological and genetic study of two glioblastomas, one case arising de novo and the other case arising 3 years after a previously diagnosed anaplastic astrocytoma, with concurrent EGFR amplification and TP-53 mutation. These anomalies were initially deemed as mutually exclusive. However, a small percentage of cases have been found with both anomalies although at a significantly lower level than could be expected. We have analyzed these two cases cytogenetically and by molecular studies in order to detect additional alterations associated with this phenotype. Cytogenetically, both cases showed in common the monosomy of chromosomes 10 and 17. At the molecular level, a rare mutation of TP-53 was found in the secondary glioblastoma and hypermethylation of the promoter region of p16(INK4a) and p14(ARF) genes were observed in the primary and secondary glioblastoma, respectively.

Primary glioblastoma with EGFR amplification and a ring chromosome 7 in a young patient

Glioblastoma is the most common primary tumor of the central nervous system, but the underlying genetic changes that give rise to these tumors are still poorly understood. We report a primary glioblastoma with an unusual age of presentation. The patient was a 22-year-old man with a survival of 16 months. Morphological findings showed an increase of cellularity with positive GFAP and EGFR expression, increase of proliferate index, vascular hyperplasia with glomeruloid structures and necrosis. Molecular analysis showed EGFR amplification. No mutations of the TP53 or amplification of MDM2 and CDK4 were detected. Neither homozygous deletion of the 9p21 locus genes nor aberrant methylation were found. The cytogenetic study showed a clonal karyotype. The metaphases presented, among other anomalies, a small ring chromosome and double-minutes chromosomes. Using FISH and CGH techniques, it was found that the ring chromosome was a partial trisomy of chromosome 7, and the region implicated corresponded to 7p13-q21. Partial trisomies in glioblastoma could play an important role in defining those regions where genes implicated in this tumor process may be found. We studied the possible correlation of these findings with the tumoral phenotype.

Association of chromosome 7, chromosome 10 and EGFR gene amplification in glioblastoma multiforme

Glioblastoma multiforme (GBM) is characterized by intratumoral heterogeneity in both histomorphological and genetic changes, displaying a wide variety of numerical chromosome aberrations, the most common of which are trisomy 7 and monosomy 10. The amplification of the epidermal growth factor receptor (EGFR) gene is the most frequently reported genetic abnormality. The associations between these parameters and their implication in the tumoral progression are poorly understood. We performed simultaneous fluorescence in situ hybridization (FISH) with centromeric DNA probes for chromosomes 7 and 10 in smear preparations, and EGFR gene amplification by PCR from 25 cases of GBM. Trisomy/ polysomy for chromosome 7 was present in 76% of cases and monosomy 10 in 68%. Both alterations were associated in 56% of cases. The EGFR gene was amplified in 52% of tumors; in 44% associated with trisomy/ polysomy 7, and in 36% with monosomy 10. The three parameters were associated together in 28% of cases. Kaplan-Meier survival rate analysis demonstrated lower survival rates in patients with monosomy 10, trisomy 7, and monosomy associated with trisomy 7. The other combinations were not different in frequency in relation to survival. In the present study, trisomy/polysomy 7 and monosomy 10 have been found to be frequently associated. The combination of both anomalies is probably important in the tumorigenesis of glioblastoma. Moreover, this association is apparently independent of EGFR gene amplification, which could be a later event in this process.

Complex rearrangement of chromosomes 6 and 11 as the sole anomaly in atypical teratoid/rhabdoid tumors of the central nervous system

Atypical teratoid/rhabdoid tumor of the central nervous system is a rare childhood tumor with a distinct histologic appearance and an aggressive clinical course. Few tumors have been analyzed cytogenetically. The only consistent chromosomal abnormality identified in some of these tumors has been monosomy or deletions of chromosome 22; in others, a normal chromosome 22 was present. The authors report an atypical teratoid/rhabdoid neoplasm of the central nervous system with a novel complex rearrangement affecting chromosomes 6 and 11 as the sole anomaly. The involvement of region 11p15 could be important in the pathogenesis of this entity.

Meningiomas: karyotypes and histological patterns

The cytogenetic findings, based on G-banding, in six meningiomas are reported. Normal karyotypes were found in three cases and monosomy of chromosome 22 in the remaining three. In one of these three cases, a malignant meningioma, several chromosomes were lost, gonosome Y included. The possible significance of the association of chromosome alterations in meningiomas with the histology of the tumor and its biological aggressivity is discussed.

Giant-cell tumor of bone, stage II, displaying translocation t(12;19)(q13;q13)

A new case of giant-cell tumour (GCT) of bone with benign histological features, clinical stage II, has been reviewed with immunohistochemistry and electron microscopy. After short-term tissue culture the karyotype, using G-banding techniques, presented a consistent translocation t(12;19)(q13;q13). Nude mice xenografts of the tumour were unsuccessful after 6 months of follow-up. Presence of such chromosomal rearrangement may be related to locally aggressive, histologically benign giant-cell tumors of bone.