Chromosomal evolution and tumor progression in a myxoid liposarcoma

Atypical lipomatous tumors/well-differentiated liposarcomas: clinical outcome of 67 patients

Atypical lipomatous tumors/well-differentiated liposarcomas are low-grade malignant mesenchymal neoplasms with high propensity to local recurrence and potential to dedifferentiate to higher grades over time. However, the published risks of local recurrence and dedifferentiation vary, and no unified treatment and follow-up plan has been accepted. We performed a study to evaluate the long-term clinical behavior and proper treatment and follow-up strategy for these tumors. We retrospectively reviewed the files of 101 patients treated between 1990 and 2008 with the diagnosis of atypical lipomatous tumors/well-differentiated liposarcomas. For 67 of these patients, complete data and 2-year minimum follow-up were available and were included in the study; 47 patients (group A) had primary surgical treatment at our institution and 20 patients (group B) were referred after ≥1 local recurrences. Mean follow-up was 81 months (range, 24-229 months). The local recurrence rate of primary atypical lipomatous tumors/well-differentiated liposarcomas was 10.6% (5/47 group A patients). The local re-recurrence rate of the recurrent atypical lipomatous tumors/well-differentiated liposarcomas was 52% (13/67 group A and B patients). Recurrences developed as late as 140 months after diagnosis and treatment. The rate of dedifferentiation at recurrences was 4% (1/25 group A and B patients with recurrent tumors). No patients developed metastases. Atypical lipomatous tumors/well-differentiated liposarcomas are associated with an increased rate of local re-recurrence and low risk of dedifferentiation at recurrences. Long-term follow-up is recommended for early diagnosis and treatment of local recurrences.

Running GAGs: myxoid matrix in tumor pathology revisited: what's in it for the pathologist?

Ever since Virchow introduced the entity myxoma, abundant myxoid extracellular matrix (ECM) has been recognized in various reactive and neoplastic lesions. Nowadays, the term "myxoid" is commonly used in daily pathological practice. But what do today's pathologists mean by it, and what does the myxoid ECM tell the pathologist? What is known about the exact composition and function of the myxoid ECM 150 years after Virchow? Here, we give an overview of the composition and constituents of the myxoid ECM as known so far and demonstrate the heterogeneity of the myxoid ECM among different tumors. We discuss the possible role of the predominant constituents of the myxoid ECM and attempt to relate them to differences in clinical behavior. Finally, we will speculate on the potential relevance of this knowledge in daily pathological practice.

Myxoid liposarcoma of the ankle

Liposarcomas are among the most common soft tissue sarcomas, but are rarely found in the foot or ankle. Certain types of liposarcomas, which range from well-localized low-grade entities to highly aggressive neoplastic lesions, may resemble common benign soft tissue lesions. Myxoid liposarcoma is the most common type of liposarcoma and is important to recognize and differentiate from a benign soft tissue lesion because it may be a limb-threatening and/or life-threatening tumor. A thorough literature review and perplexing case study of myxoid liposarcoma of the ankle is presented.

Deletion 6q in three cases of mixed-type liposarcoma in addition to t(12;16)(q13;p11)

We report the cytogenetic findings in three mixed liposarcoma following short-term cultures. During the course of cytogenetic investigation of various types of liposarcomas, we observed an interstitial deletion of the long arm of chromosome 6 together with the translocation (12;16)(q13;p11) in three tumors. Translocation (12;16) is associated with myxoid and mixed (myxoid/round cell) liposarcomas, although deletion of chromosome 6 has been observed in only a few of these tumors. Our findings suggest that del(6), as an additional change in myxoid liposarcoma, is probably related to tumor progression.

Cytogenetic intratumor heterogeneity in soft tissue tumors

Multiple (two to seven) samples, obtained from the same surgical specimen or at different occasions, were analyzed in 54 benign and malignant soft tissue tumors, to investigate cytogenetic clonal evolution. In 28 tumors only normal karyotypes were found. Ten tumors had abnormal karyotypes, but were noninformative, most often due to a high level of karyotypic complexity or great cell-to-cell variation. Sixteen tumors were informative: four (leiomyosarcoma, liposarcoma, malignant Schwannoma, and a benign mesenchymal tumor, probably leiomyoma) had identical karyotypes in different samples, whereas the remaining 12 tumors (seven malignant fibrous histiocytomas [MFH], two leiomyosarcomas, two liposarcomas, and one synovial sarcoma) displayed intersample heterogeneity. Also, intrasample heterogeneity was detected; more than one clone was found in 21 of 73 samples with aberrations from 26 tumors. The different clones were related in all cases except two. In seven cases, samples from different occasions were studied, and clonal evolution could be evidenced in five of them, whereas in two cases the karyotypes remained unchanged. The results indicate that the acquisition of ring chromosomes is an early event in the development of MFH and possibly also pleomorphic liposarcoma. The findings, together with previous data, also indicate that rearrangements of 19p13 are late events in the progression of pleomorphic sarcomas. The overall conclusion from this study is that cytogenetic heterogeneity is common in soft tissue tumors, and that this might influence the evaluation of cytogenetic and molecular genetic findings.

Cytogenetics of tumors of soft tissue and bone. Implication for pathology

Pathologists should be aware of the existence of diagnostically useful chromosomal rearrangements in several soft tissue and bone tumors. They include rearrangement of 8q12 in lipoblastomas, ring chromosomes in atypical lipomas, ring and giant marker chromosomes in well differentiated liposarcomas, t(12;16)(q13;p11) in myxoid liposarcomas, rearrangement of 7p21-22 in low-grade endometrial stromal sarcomas, t(2;13)(q37;q14) in alveolar rhabdomyosarcomas, t(X;18)(p11.2;q11.2) in synovial sarcomas, t(12;22) (q13;q13) in clear cell sarcomas, t(11;22)(q24;q12) in Ewing's sarcomas and peripheral neuroepitheliomas, and t(9;22)(q21-31;q11-12) in extraskeletal myxoid chondrosarcomas.

Cytogenetic evolution in primary tumors, local recurrences, and pulmonary metastases of two soft tissue sarcomas

The karyotypic pattern at different stages of tumor development may provide information on tumor progression but few data are available regarding human solid tumors. Cytogenetic analysis was performed on the primary tumor and four lung metastases of a synovial sarcoma, and the primary tumor, two consecutive local recurrences, and six pulmonary metastases, obtained at two different occasions, of a malignant fibrous histiocytoma (MFH). Simultaneous existence of more than one cytogenetically aberrant clone was also assessed through analysis of more than one sample from the same surgical specimen. Clonal chromosome aberrations were detected in all samples from the synovial sarcoma, and in both local recurrences and five of the metastases from the MFH. All clones in both tumors were cytogenetically related. The primary synovial sarcoma tumor contained two clones, one of which was also found in the lung metastases, together with a third clone that had acquired additional aberrations. Four clones with a near-tetraploid chromosome number and complex aberrations were identified in the MFH. Likely evolutionary pathways could be deduced in both cases. In the patient with synovial sarcoma one of the pulmonary metastases, rather than the primary tumor, might well have been the source of another of the pulmonary metastases. In the MFH the cytogenetic findings indicated the presence of two co-existing lineages in the primary tumor, one giving rise to the local recurrences and one to the pulmonary metastases. Our findings show that cytogenetic analysis can be used to establish the chronologic relationships between different clones in primary tumors, local recurrences and distant metastases, to determine what genetic changes are of importance for the metastatic capability of tumor cells, and to help establish the origin of the metastatic lesions.

Cytogenetic findings in 33 osteosarcomas

Thirty-three osteosarcomas (OS) were analyzed cytogenetically. Clonal chromosome changes were detected in 17 cases. Six tumors had chromosome numbers in the diploid range, 6 in the triploid range, 1 in the tetraploid range and 1 in the pentaploid range, while 3 tumors had multiple clones with different ploidy levels. Including the present 17 tumors, a total of 27 OS with clonal aberrations have been reported. The recognizable structural rearrangements in these 27 tumors clustered to chromosome arms 1p, 1q, 3p, 3q, 7q, 11p, 17p and 22q. Chromosome bands 1q11, 1q21, 1q42 and 7q11 were the most frequently rearranged, and the most common numerical rearrangements were -3, -10, -13 and -15. Supernumerary ring chromosomes, in 2 tumors as the sole change, were found in all 3 parosteal OS, which is in agreement with the findings in 1 previously reported parosteal OS. The association between ring formation and parosteal morphology represents the first cytogenetic-morphologic entity among OS.

Aberrations of chromosome segment 12q13-15 characterize a subgroup of hemangiopericytomas

BACKGROUND

In later years, several characteristic acquired chromosomal aberrations have been identified in mesenchymal tumors. Many of these aberrations, either alone or with histopathologic and clinical data, are useful in diagnosis. The cytogenetic profile of hemangiopericytomas has been poorly investigated.

METHODS

Short-term cultures from four spindle cell tumors were cytogenetically analyzed.

RESULTS

Clonal acquired chromosome aberrations were found in three of the four tumors: inv(12) (q14q24) in a malignant hemangiopericytoma, a supernumerary der(3)t(3;12) (p21-23;q13-15) in a benign hemangiopericytoma, and t(6;12;19) (p21;q13;p13) in a spindle cell sarcoma that was histologically a malignant hemangiopericytoma or a synovial sarcoma. The fourth tumor, a malignant hemangiopericytoma, had a normal karyotype. The tumors with inv(12) and t(6;12;19) had subclones with trisomy 5 in addition to the structural changes.

CONCLUSIONS

The current findings and the literature data indicate that a subgroup of hemangiopericytomas is characterized by rearrangement of chromosome segment 12q13-15.

Chromosome aberrations and cytogenetic intratumor heterogeneity in chondrosarcomas

Clonal chromosome aberrations identified after short-term culture are presented for 13 chondrosarcomas; in 5 cases both the primary tumors and local recurrences were studied. The stemline chromosome number was hypodiploid or hyperhaploid in 9 tumors. The most frequent numerical anomalies were, in falling order of frequency, loss of chromosomes Y, 10, 13, and 6, and gain of chromosomes 7 and 20. No recurrent structural rearrangement was found, but chromosome bands 5q13, 1q21, 7p11, and 20q11 were each involved in three different rearrangements. Karyotypic heterogeneity was assessed in two different ways: as the presence of more than one clone in one sample and as the presence of different clones in different samples from the same surgical specimen. Clonal karyotypic evolution was demonstrated in 6 of the 7 cases in which two or more samples could be investigated. All 6 showed intersample heterogeneity. Intrasample heterogeneity was found in only 5 of the 28 samples with aberrations. By comparing the incidences of the nonrandomly occurring aberrations in stemlines and sidelines in the heterogeneous tumors, it was possible to conclude that loss of chromosome 13 and rearrangement of band 5q13 were early events in the clonal evolution.

Chromosome abnormalities in liposarcomas

We performed a cytogenetic study of short-term cultures from fresh surgical specimens obtained from four patients with liposarcoma. Myxoid liposarcomas (cases 1-3) were associated with a specific translocation between chromosomes 12 and 16. Trisomy 8, a nonrandom secondary aberration in myxoid liposarcoma, was observed in the third case as the only additional change. Round cell liposarcoma (case 4) showed complex chromosomal aberrations affecting chromosomes 1, 2, 5, 6, 7, 13, 14, 17, 19, and 22. Neither band 12q13 nor 16p11 was visibly rearranged. Three subgroups of liposarcomas are proposed. The first group is characterized by t(12;16)(q13;p11), the second group by ring chromosomes, telomeric associations, and giant markers, and the last by complex numerical and structural aberrations.

Rearrangement of the transcription factor gene CHOP in myxoid liposarcomas with t(12;16)(q13;p11)

Most myxoid liposarcomas (MLS) are characterized cytogenetically by a t(12;16)(q13;p11). It is reasonable to assume that this translocation corresponds to the consistent rearrangement of one or two genes in 12q13 and/or 16p11, and that the loci thus affected are important in the normal control of fat cell differentiation and proliferation. We have used Southern blot technique to test whether a gene of the CCAAT/enhancer binding protein (C/EBP) family, CHOP, which maps to 12q13 and is assumed to be involved in adipocyte differentiation, could be the 12q gene in question. Using a cDNA probe that spans the CHOP coding region, we detected one rearranged and one wild type allele in nine of nine MLS with t(12;16). Using PCR generated, site-specific probes corresponding to the non-coding exons 1 and 2 and intron 2 of CHOP, rearrangements in five of seven tumors mapped to the 2.4 and 1.6 kbp PstI fragments that contain the first two exons and introns of the gene and the upstream promoter region. In contrast to the findings in MLS, no tumor without a t(12;16) exhibited aberrant CHOP restriction digest patterns. These tumors included one highly differentiated liposarcoma with abnormal karyotype but no involvement of 12q13, seven lipomas with various cytogenetic aberrations of 12q13-15, two uterine leiomyomas with t(12;14) (q14-15;q23-24), and one hemangiopericytoma and one chondroma, both of which also had 12q13 changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Metachronous second primary malignant fibrous histiocytoma in two skeletal muscles

The first recorded case of a metachronous second primary malignant fibrous histiocytoma (MFH) of soft tissue is presented. The patient, who has been followed every two months since the treatment of his buttock sarcoma by neoadjuvant therapy, is free of disease 24 months later. The clinical presentations, different histologies, and DNA contents of these two MFHs are consistent with metachronous primary sarcomas. The literature on second primary neoplasms is discussed.

The interleukin-4 receptor gene (IL4R) maps to 16p11.2-16p12.1 in human and to the distal region of mouse chromosome 7

The chromosomal location of both the human and the mouse interleukin-4 receptor (IL4R) genes have been determined. The human gene was localized to 16p11.2-16p12.1 by in situ hybridization and confirmed by Southern blot analysis of DNA from a panel of mouse-human hybrid somatic cell lines. The mouse homolog was positioned in the distal region of chromosome 7 by interspecific backcross analysis. The results suggest that the IL4R locus is unlinked to other members of the hematopoietin receptor family. Interestingly, the position on human chromosome 16 suggests that the IL4R may be a candidate for rearrangements, as 12;16 translocations are often associated with myxoid liposarcomas.