Supernumerary ring chromosomes derived from the long arm of chromosome 12 as the primary cytogenetic anomaly in a rare soft tissue chondroma

Supernumerary ring chromosomes varying with respect to both size and number were found as the primary cytogenetic anomaly in a rare benign soft tissue chondroma resected from the floor of the mouth of a 3-year-old girl. Rever se fluorescence in situ hybridization paint probes prepared by polymerase c hain reaction from microdissected rings produced fluorescent signal over tw o large but discontinuous parts of the chromosome 12 long arm, subdivided i nto four regions. This case expands the spectrum of mesenchymal neoplasms i n which ring chromosomes have been described as the primary genetic anomaly . A review of the literature reporting similar findings in other soft tissu e tumors further supports the possibility that low-level amplification of o f chromosome 12 long-arm regions may contribute to abnormal cellular prolif eration in a variety of mesenchymal tumors. Genes implicated in the control of the cell cycle such as sarcoma amplified sequence(SAS), the human homol og of the murine double-minute type 2 gene (MDM-2), proto-oncogenes CHOP/GA DD153, GLI. A2MR, cyclin-dependent kinase (CDK4), and the high mobility gro up (HMGIC) gene implicated in mesenchymal tumorigenesis are all located on the long arm of chromosome 12. Chromosomal abnormalities involving the 12q1 3-q15 region are associated with a wide range of benign soft tissue tumors and sarcomas. (C) Elsevier Science Inc., 2000. All rights reserved.