Ring chromosome

About: Ring chromosome is a research topic. Over the lifetime, 1546 publications have been published within this topic receiving 31061 citations. The topic is also known as: supernumerary circular chromosome.

Different karyotypic features characterize different clinicopathologic subgroups of benign lipogenic tumors

Abstract: On the basis of the cytogenetic analysis of tumor cells from a total of 50 lipomas, we conclude that 4 main cytogenetic subtypes may be recognized: (1) tumors with normal karyotype (18 cases); (2) tumors with rearrangements of 12q13-14 (18 cases); (3) tumors with ring chromosomes (6 cases); (4) tumors with other clonal changes (8 cases). This karyotypic heterogeneity parallels other disease characteristics in the following manner: all 6 tumors containing ring marker chromosomes were histopathologically classified as atypical lipomas (6 of the 50 tumors were diagnosed as atypical) or (in 2 cases) lipomas with foci of atypia. In only one single solitary lipoma with focal atypia were no ring chromosomes detected in the tumor cells. This contrasts strongly with the findings in typical solitary lipomas, where rings were found in only 2 of 37 tumors, or, if the 3 tumors with focal atypia are excluded, in none of 34. Furthermore, all 7 multiple lipomas were karyotypically normal, whereas among solitary tumors the corresponding proportion was 11 of 43. We conclude that ring marker chromosomes may be a distinguishing cytogenetic feature of atypical lipomas, and that multiple lipomas, in contrast to their solitary counterparts, are karyotypically normal. These findings emphasize that different tumorigenic pathways are likely to be involved in different groups of benign lipogenic neoplasms.

Cytogenetic findings in 19 malignant bone tumors.

Abstract: BACKGROUND: The majority of karyotypes observed in osteosarcomas (OS) and chondrosarcomas (CS) are complex. Specific chromosomal abnormalities have not yet been characterized in either tumor except for a ring chromosome in parosteal OS. The purpose of this study was to determine recurrent chromosomal abnormalities and establish a possible correlation between the cytogenetic changes and the pathologic findings. METHODS: Ten OS and nine CS were cytogenetically analyzed. Tumor samples were obtained from patients having a resection or incisional biopsy. Cytogenetic study of short term cell cultures included harvesting and G-banding, which were performed by routine methodologies. RESULTS: Clonal abnormalities were observed in six OS and six CS. Modal chromosome numbers ranged from near diploid to near tetraploid in both types of tumors. The structural rearrangements observed in OS involved mostly chromosomes 1, 2, 6, 12, and 17. Nonreciprocal translocations were the most frequent event. Two OS had a single clonal abnormality involving 11p15 and 14q32, respectively. Double minute chromosomes were observed in three cases. In CS, the most frequent structural abnormalities were nonreciprocal translocations and deletions involving numerous chromosomes. Rearrangements of 1p together with other abnormalities were observed in four CS. CONCLUSIONS: The karyotypes were usually complex consisting of numerical and structural changes, particularly in high grade tumors. Rearrangements of 11p15 and 14q32 in OS and possibly 1p in CS were found as primary cytogenetic aberrations. Cytogenetic analysis in more cases of OS and CS together with molecular studies are necessary to characterize further the consistent genetic changes in these tumors.

19p marker chromosome correlates with relapse in malignant fibrous histiocytoma

Abstract: In this study, we examined the relationship of 19p13 aberrations, usually leading to addition of unknown material (19p+), and ring chromosomes to clinical outcome in patients with malignant fibrous histiocytoma (MFH). Analysis of 69 MFHs revealed 19 tumors with 19p+ and 24 tumors with ring chromosomes. After a median follow-up period of 36 months, 24 patients developed metastases, and 27 patients developed local recurrences. Ten patients had both local recurrences and metastases. Local recurrence was more common in association with 19p+ than without. Metastasis was more common with 19p+ tumors in high-risk patients (tumor size > 5 cm and grade III-IV; n = 48) than those without 19p+. There was a trend suggesting fewer relapses after tumors with ring chromosomes. 19p+ may be an independent marker of unfavorable outcome in MFH.