1/5. ring chromosomes in a malignant mesenchymoma.We report, for the first time, the cytogenetic and molecular genetic constitution of a human mesenchymoma. As in several other soft tissue sarcomas, supernumerary ring and rod-shaped marker chromosomes were observed next to an otherwise normal diploid karyotype. Comparative genomic in situ hybridization and whole chromosome painting experiments revealed that chromosome 1q21-q25 and 12q14-q15 sequences were amplified, and that these sequences resided on the supernumerary marker chromosomes. We assume that, in this malignant mesenchymoma, the observed chromosomal anomalies may be associated with its well differentiated liposarcomatous component.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/5. Characterization of centromere alterations in liposarcomas.Supernumerary ring and large marker chromosomes are a characteristic of atypical lipomas and well-differentiated liposarcomas (ALP-WDLPS) and are composed of amplified 12q14-15 sequences in association with variable segments from other chromosomes. Although stably transmitted, these chromosomes contain centromeric alterations, showing no detectable alpha-satellite sequences. We performed C-banding, fluorescence in situ hybridization, and immunostaining with anti-centromere antibodies in 8 cases of liposarcomas with supernumerary rings and large markers, including 5 ALP-WDLPS and 3 dedifferentiated-LPS and high-grade LPS. Our results with alpha-satellite probes and anti-CENPB antibodies confirm the lack of detectable alpha-satellite sequences in the five ALP-WDLPS supernumerary chromosomes, whereas centromeric activity was proved by the detection of kinetochores by using anti-CENPC antibodies. In contrast, the high grade and dedifferentiated liposarcomas showed a different pattern. In 2 cases, amplified chromosome 12 sequences, including amplification of alpha-satellite 12 sequences in 1 case, were present on chromosomes with typical centromeres. In another case, the rings were similar to WDLPS-ALP rings, but a large marker contained a chromosome 5 centromere and amplified alpha-satellite sequences from chromosome 8. ALP-WDLPS is the first example of a tumor class for which the presence of stable analphoid chromosomes is a constant and specific abnormality. Formation of newly derived centromeres, so-called neocentromeres, could be an original and effective way to maintain a selective advantage in neoplastic cells by conferring stability to the supernumerary chromosomes of ALP-WDLPS. The activation of normally non-centromeric sequences might be obtained by an epigenetic mechanism due to the peculiar chromatin conformation of these highly complex chromosomes.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
3/5. Dedifferentiation of a well-differentiated liposarcoma to a highly malignant metastatic osteosarcoma: amplification of 12q14 at all stages and gain of 1q22-q24 associated with metastases.Well-differentiated liposarcomas (WDLPS), especially those located in the retroperitoneum, may occasionally undergo dedifferentiation. Although this process is associated with a more aggressive clinical course, dedifferentiated liposarcomas rarely produces metastases. The case reported here is rather uncommon: A retroperitoneal WDLPS gave lung metastases that were diagnosed as highly malignant osteosarcomas. We used comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), and Southern blot analyses to characterize the copy number changes and genetic aberrations occurring at different stages of the disease. In the primary tumor, the only detectable aberration was amplification of 12q13-q14, which was present only in a fraction of the cells and revealed by FISH analysis. High-level amplification of 12q13-q14, involving CDK4, MDM2, and HMGIC, was seen both in the relapse and the metastases. The second most common change, gain or high-level amplification of 1q22-q24, was detectable by CGH only in the osteogenic metastases, as was loss of the distal 2q. FISH analyses revealed considerable heterogeneity in the samples, and the percentage of cells showing aberrations was significantly higher in the metastatic samples. In particular, increased copy numbers of 789f2, a marker for 1q21 amplification in sarcomas, was observed in more than 65% of the cells in the metastatic samples, but in less than 10% of the cells from the recurrent samples. These observations could indicate that 1q amplification, in particular, may be indicative of a more malignant phenotype and ability of metastasis in WDLPS, as has also been suggested by others.- - - - - - - - - - ranking = 2keywords = hybridization (Clic here for more details about this article) |
4/5. Dedifferentiated liposarcoma with extensive lymphoid component.An unusual variant of dedifferentiated liposarcoma with extensive lymphocytic component is described. A 71-year-old patient suffered from a relapse of an atypical lipomatous tumor/well-differentiated liposarcoma with early micronodular (low-grade) dedifferentiation, which had been resected 4 years before. The relapse revealed features of a dedifferentiated liposarcoma with spindle-cell, partly pleomorphic dedifferentiation and osseous metaplasia. Clearly separated from the spindle-cell areas, an extensive homogeneously dense lymphoid (lymphocytic) tumor-component was evident, with relative abrupt transition to the well-differentiated liposarcoma component. Using immunohistochemistry and PCR, the lymphoid ("lymphoma-like") infiltrate proved to be a polyclonal lymphocytic proliferation. fluorescence in situ hybridization (FISII) analysis revealed no signs of MDM2- and CDK4-gene amplification in the lymphoid areas, although within this mononuclear lymphoid population, large polymorphic nuclei displayed an amplified number of MDM2/CDK4 gene copies, indicating the presence of truly dedifferentiated tumor cells within the lymphoid component. The results favor a reactive lymphocytic infiltration versus a neoplastic one, which might be caused for example by chemoattractive agents. An extensive lymphoid "overgrowth" must be considered within the spectrum of unusual variants and in the differential diagnosis of dedifferentiated liposarcoma.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
5/5. Analysis of a giant marker chromosome in a well-differentiated liposarcoma using cytogenetics and fluorescence in situ hybridization.Well-differentiated liposarcomas (LPS) are cytogenetically very complex, characterized by giant marker chromosomes, ring chromosomes, and telomeric associations. We report a case of well-differentiated LPS in which the only cytogenetic anomaly was an additional giant marker. In an attempt to identify the origin of this marker, centromeric probes (chosen on the basis of the morphology of the marker) to chromosomes 1,2,3,4,6,7,8,9,10,11,12,16,17, and X and a shared satellite probe for chromosomes 1,5, and 19, were used with fluorescence in situ hybridization (FISH). This was successful at eliminating certain chromosomes as candidates for centromeric trisomy but could not identify the origin of the marker. This case is unusual in that it does not conform to the typical cytogenetic pattern for well-differentiated LPS and is the first known example with an apparently normal diploid karyotype with only one additional change.- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |