Chromosomal changes in soft-tissue sarcomas. A new diagnostic parameter

Translocation t(12;16)(q13;p11) in myxoid liposarcoma of a child and implication of the human int-1 gene in tumorigenesis

Cytogenetic and gene analyses were performed in a child with myxoid liposarcoma (MLS). A reciprocal chromosome translocation t(12;16)(q13;p11) was found in the tumor cells. This result, combined with the previous reports of a similar translocation in adult MLS strongly suggests that this translocation may be a characteristic cytogenetic marker in MLS. The human int-1 gene has been reported to be located close to the 12q13 breakpoint associated with MLS. Therefore, we examined the rearrangement of the human int-1 gene by Southern blotting analysis. When genomic DNAs from the tumor cells were digested with KpnI, EcoRI and BamHI, no difference was seen compared to peripheral blood leukocytes (PBL) DNAs from a normal individual. However, with HindIII digestion there appeared a 3.1 kb fragment in tumor cell DNA as compared to a 2.8 kb fragment in DNAs prepared from normal PBL and the patient's PBL. These findings suggest that the int-1 gene may be implicated in tumorigenesis of MLS with t(12;16)(q13;p11).

Characteristic karyotypic anomalies identify subtypes of malignant fibrous histiocytoma

Cytogenetic analysis of short-term cultures from 25 malignant fibrous histiocytomas (MFH) revealed clonal chromosome abnormalities in 17 tumors: ten storiform-pleomorphic and seven myxoid MFH. Telomeric associations, rings, and dicentric chromosomes were present in 11 tumors and cytogenetic signs of gene amplification (homogeneously staining regions and double minute chromosomes) in four. The breakpoint distribution of the numerous structural rearrangements was nonrandom. The chromosome bands most frequently affected were 19p13 (in eight tumors; eight rearrangements gave rise to 19p+ markers, some of which looked similar, and an r(19) was found in one case), 11p11 (in seven tumors; three translocations and four deletions), 1q11 (in seven tumors; one translocation and six deletions), and 3p12 (in six tumors; all deletions). Other bands involved at least four times were 1p36, 5p15, and 20q13. Of particular clinical interest was the observation that tumors with 19p+ seemed to have a pronounced tendency to recur locally (local recurrence in five of eight tumors with 19p+ compared to one of nine in tumors without this aberration; observation period 4-16 months).

Cytogenetic subtype involving chromosome 13 in lipoma. Report of three cases

We report three lipomas with rearrangements of chromosome 13. The karyotype of the tumors studied were 45,XX,-8,+der(8)t(8;13)(q22;q12),del(10)(p12),-13; 46,XY,del(13)(q12q22), and 46,XY,t(11;12)(q23;q13),del(13)(q12q22), respectively, revealing common involvement of band 13q12 in the rearrangement. Three other lipomas with aberrations of bands 13q12-q13 have been reported, suggesting that such tumors with abnormalities of chromosome 13 could represent a subgroup of lipoma in addition to those already reported with abnormalities of chromosomes 12q and 6p. The rearrangements of #13 in all these cases also involved loss of the band 13q14 to which the antioncogene associated with retinoblastoma and osteosarcoma is localized. Detailed clinical, histopathologic, and molecular studies should help to further characterize the various cytogenetically defined subgroups of lipoma.