Complex chromosome rearrangements in an extraabdominal desmoid tumor

Molecular cytogenetic characterization of desmoid tumors

Desmoid tumors are benign neoplasms of the fibromatosis group. Data on their acquired chromosomal changes are sparse and, therefore, we wanted to ascertain what genomic losses and gains these tumors may have incurred. DNA was extracted from a total of 26 formalin-fixed, paraffin-embedded desmoid tumors followed by comparative genomic hybridization (CGH) and interphase fluorescence in situ hybridization (I-FISH) analyses. Ten of 12 informative tumors were normal by CGH; the two abnormal ones had loss of chromosome 6 and loss of 6q and gain of chromosome 20, respectively. I-FISH analyses with an alpha-satellite probe specific for chromosome 8 of 26 desmoids, including one tumor that by karyotyping had +i(8)(q10), showed no evident abnormalities. An explanation for the relatively high frequency of genomically normal tumors by CGH seen in this study may be sought in the fact that as many as 10 of the 12 informative tumors were abdominal desmoids, a subset of tumors also previously found to exhibit genomic changes only rarely. It is therefore possible that abdominal desmoids might be non-neoplastic tumors or neoplastic tumors with genetic changes too small to be discovered by CGH, whereas desmoid tumors from other locations exhibit detectable genomic changes at a significantly higher frequency.

Cytogenetic instability, predominantly involving chromosome 1, is characteristic of elastofibroma

Elastofibroma, an unusual pseudotumor composed of excessive collagen and abnormal elastic fibers, has rarely been subjected to cytogenetic analysis. Only two cases have been previously defined, both of which demonstrated nonclonal abnormalities. In the present study, three cases of elastofibroma were cytogenetically analyzed. Abnormalities of the short arm of chromosome 1 were seen in all three cases (either clonally or as the most frequently involved region among nonclonal aberrations). In addition, a translocation involving chromosomes 8 and 12 was detected as a clonal rearrangement in one of the three cases. The observation of clonal abnormalities in elastofibroma suggests that this lesion may represent a neoplastic rather than a reactive process.

Cytogenetic, clinical, and morphologic correlations in 78 cases of fibromatosis: a report from the CHAMP Study Group. CHromosomes And Morphology

Whether fibromatoses are neoplastic or reactive lesions has long been controversial and the relationship, if any, between the superficial and deep forms (desmoid tumors) are poorly understood. Clinical, pathologic, and cytogenetic data of 78 cases of fibromatosis were analyzed and correlated with each other. The results demonstrate that clonal chromosome aberrations are a common feature of this entity, being present in 46% of desmoid tumors, although less frequent in the superficial types (10%). In the deep-seated extra-abdominal fibromatoses, trisomies 8 and 20 and loss of 5q material were the only recurrent features. No correlation between +8 and local recurrence was found. Our findings provide additional evidence for the neoplastic nature of fibromatoses.

The cytogenetic and molecular characterization of benign and malignant soft tissue tumors

Cytogenetic analyses of benign and malignant soft tissue tumors have led to the description of recurrent, specific, and even pathognomonic chromosomal translocations and/or other rearrangements in most types of soft tissue tumors. The consistent karyotypic rearrangements have provided critical diagnostic information in this group of neoplasms that often presents significant diagnostic challenges to the clinician and the pathologist. These findings have also been instrumental in the characterization of the abnormalities at the molecular level. Novel genes have been isolated from the translocation junctions and the mechanisms of their deregulation identified. This has increased our understanding of the histogenesis of these tumors, paved the way for the molecular diagnosis of many sarcomas, aided in directing therapy, and also provided important prognostic information.

Desmoid tumour: a pleomorphic lesion

BACKGROUND

Desmoid tumour (DT) is an uncommon locally invasive non-metastasizing neoplastic lesion. The aetiology of this tumour is unknown and its treatment is controversial. Twelve cases of DT are presented and the literature is reviewed.

METHODS

Twelve cases of DT treated at our institution during a 3.5-year period are analysed and the literature reviewed. Ten patients were referred with a primary tumour, one with local recurrence and one patient with a second primary desmoid tumour. One patient had multiple mesenteric DT (familial adenomatous polyposis coli-FAP), and in the remaining 11 patients the tumour was located in the abdominal wall in four, at an extremity in three, in the upper back in two patients, in the pelvis in one and retroperitoneally in one.

RESULTS

The largest mesenteric DT was marginally excised en bloc with total jejunectomy. In the remaining 11 DT, complete excision to microscopically tumour-free margins was possible in nine cases and to microscopically involved margins in two cases. At a mean follow-up of 22 months (range 7-38 months), one patient was alive with stable disease (Gardner's syndrome), 10 patients were alive and free of recurrence and one patient (9%) developed local recurrence which was re-excised-she is disease-free 10 months later.

CONCLUSIONS

Complete excision is the main modality of treatment for primary and recurrent DT. This is feasible in most cases except for tumours involving the base of the bowel mesentery. Surgical resection alone achieved local control of the tumour in most of the patients in this series (92%).

Trisomies 8 and 20 characterize a subgroup of benign fibrous lesions arising in both soft tissue and bone

Trisomy 8 and trisomy 20 are nonrandom aberrations in desmoid tumors. The presence of these trisomies in related benign fibrous lesions of bone has not been previously addressed. In this study, 22 specimens from 19 patients diagnosed with desmoid tumor, desmoplastic fibroma, periosteal desmoid tumor, osteofibrous dysplasia, or fibrous dysplasia were examined by cytogenetic analysis of short-term cultures and bi-color fluorescence in situ hybridization of cytological touch preparations or paraffin-embedded tissue with centromeric probes for chromosomes 8 and 20. Trisomy 8 and trisomy 20 were detected by molecular cytogenetic methodologies in 15 specimens, including 10 primary bone lesions. Traditional cytogenetic analysis revealed trisomy 8 in two cases of osteofibrous dysplasia. Our findings demonstrate that trisomy 8 and trisomy 20 are also nonrandom aberrations in histologically similar, but clinically distinct, benign fibrous lesions of bone.

Chromosome band 1q21 is recurrently gained in desmoid tumors

DNA sequence copy number changes were studied by comparative genomic hybridization (CGH) in 28 desmoid tumors. Changes were detected in 12 tumors (43%) with a mean of 1.4 changes per sample (range: 1 to 7). Out of 12 tumors associated with pregnancy or Gardner's syndrome, only two displayed changes. The minimal common regions of the most frequent gains were 1q21 (39%), chromosome 20 (32%), and 9p12 (21%). No high-level amplifications were detected. Losses of DNA sequences were two times less frequent than gains and the minimal common regions of the most frequent losses were 6q16-q21 (14%), 5q14 (11%), and 13q21-q31 (11%).

Muscular dystrophy associated with extra-abdominal desmoid tumor showing aberrant chromosome 1 [46,XX,add(1)(p36)]

We report on a 2-year-old girl with probable limb-girdle muscular dystrophy associated with an extra-abdominal desmoid tumor of the right mandible. This association is previously undescribed. The tumor was totally removed. Cytogenetic analysis of the tumor showed a clonal karyotypic abnormality: 46,XX,add(1)(p36) in 3 of 20 cells analyzed. Since an association of a neoplasm with limb-girdle muscular dystrophy has previously been reported in 3 cases, the two abnormalities are likely related causally. The chromosome abnormality in our patient may play a role in the occurrence of her desmoid tumor.

Desmoid tumor is a clonal cellular proliferation: PCR amplification of HUMARA for analysis of patterns of X-chromosome inactivation

Desmoid tumor is a locally aggressive, nonmetastasizing soft tissue tumor. Whether desmoid tumor is a truly neoplastic cellular proliferative process or, alternatively, an unchecked reactive process has been a subject of debate. In order to determine whether desmoid tumor is composed of a clonal cell population as opposed to being a polyclonal reactive process, analysis of patterns of X-chromosome inactivation was performed. Hematoxylin and eosin stained sections of paraffin-embedded, formalin-fixed tissues were microdissected to obtain both lesional and normal control samples, and the genomic DNAs were extracted by proteinase K digestion. Following treatment with methylation sensitive restriction endonuclease (Hha I or Hpa II), the genomic DNAs were amplified by polymerase chain reaction (PCR), using nested primers targeted to a highly polymorphic short tandem repeat (STR) of the human androgen receptor (HUMARA). In eight of 12 cases, PCR amplification of the genomic DNAs was successful, and all eight of the amplified cases were heterozygous in the size of the HUMARA target. The remaining cases could not be studied because of failure to amplify DNA. Following digestion with HhaI or Hpa II, uniform patterns of X-chromosome inactivation were found in all eight desmoid tumors, whereas normal control tissue remained heterozygous. These results confirm a clonal composition of the tumors. The demonstration of clonality in the tumors in all eight informative cases indicates that desmoid tumor is a true neoplastic process, not an unchecked polyclonal reactive process.

Trisomies 8 and 20 in desmoid tumors

A nonrandom occurrence of trisomy 8 and of trisomy 20 in desmoid tumors has been recently reported. The finding of trisomy 8 in nondividing desmoid tumor cells by in situ hybridization prompted us to evaluate, in a similar way, the occurrence of trisomy 20 and the possible occurrence of both trisomies together because their co-existence was cytogenetically observed in a few cases. Double fluorescence in situ hybridization (FISH) with centromeric probes for chromosomes 8 and 20 was performed on 16 single cell suspensions of desmoid tumors. FISH confirmed the occurrence of trisomy 8 or 20 in a single cell suspension of desmoid tumors. Both individual trisomies, and even more their association in the same cells, are rare to extremely rare in solid tumors in general and in mesenchymal tumors in particular, and are only known to occur in infantile fibrosarcoma.

Desmoids in familial adenomatous polyposis

Clinical desmoid disease affect approximately 10 per cent of patients with familial adenomatous polyposis (FAP); the subclinical rate is unknown. Desmoids are probably neoplastic rather than regenerative in origin and may arise in association with germline or somatic mutations at or beyond codon 1444 of the APC gene. Intra-abdominal desmoids behave unpredictably but are an important cause of death in those with FAP. Signal intensity on magnetic resonance imaging reflects tumour cellularity, which in part determines progression, and this may help management. Surgical treatment of advanced desmoids is hazardous, but medical treatments have limited success. Chemotherapy with doxorubicin and dacarbazine is currently under evaluation.

Desmoid fibromatosis is a clonal process

Desmoid fibromatosis is a locally aggressive proliferative soft tissue lesion of controversial nature. The authors investigated the clonality of this process by molecular genetic analysis of DNA methylation pattern at a polymorphic site at the human androgen-receptor gene (HUMARA) to examine the inactivation pattern of the X chromosome. Twenty desmoid fibromatoses including primary and recurrent lesions from 11 female patients were studied. Sixteen lesions from eight patients showed nonrandom X inactivation, consistent with a clonal origin and, therefore, a true neoplastic nature. Furthermore, multiple recurrent lesions from two patients exhibited the same inactivation pattern as the corresponding primary lesions, suggesting that they were derived from the same cell clone as the primary lesion. One patient was homozygous at the HUMARA locus, and two patients had the same skewed pattern in their normal and lesional tissues. The authors also found that digestion with HpaII, but not HhaI, failed to generate a nonrandom X inactivation pattern in some of the cases, suggesting that the methylation status at the HpaII sites was altered in some lesions, and that HhaI should be used to verify results and to avoid incorrect conclusions.

Infant cardiac fibroma with clonal t(1;9)(q32;q22) and review of benign fibrous tissue cytogenetics

Cardiac fibromas are rare lesions which occur more frequently in infants and children than in the adult population. These tumors are nonmalignant proliferations of connective tissue most often found in the left ventricular myocardium or septal myocardium. No cytogenetic studies of cardiac fibromas have been reported. We report a case of an infant with a subepicardial tumor in whom the cytogenetic analysis showed a clonal reciprocal translocation, 46,XY,t(1;9)(q32;q22),inv(9)(p11q12)c. We review the literature regarding cardiac fibromas and briefly discuss the cytogenetics of benign fibrous neoplasias.

Chromosome aberrations in desmoid tumors. Trisomy 8 may be a predictor of recurrence

Cytogenetic analyses of short-term cultures revealed clonal chromosome aberrations in 6 of 13 desmoid tumors. These aberrations included two consistent events, trisomy 8 (n = 4) and trisomy 20 (n = 3), which have not been reported previously in desmoid tumors. Because trisomy 8 was found in two recurrent desmoid tumors, we used fluorescent in situ hybridization (FISH) methodology to evaluate chromosome 8 in 25 paraffin-embedded and frozen desmoid specimens. The FISH studies demonstrated that both patients with cytogenetic trisomy 8 at the time of recurrence also had had trisomy 8 in primary tumors 4 years earlier. The proportion of trisomy 8 cells in these cases did not change substantially between original diagnosis and recurrence. The FISH studies also revealed trisomy 8 in one recurrent desmoid tumor which had been cytogenetically unremarkable and revealed trisomy 8 in one recurrent desmoid that had not been karyotyped. Four of six patients with trisomy 8 had been followed for more than 1 year, and the desmoid tumors in each of these 4 patients recurred. By contrast, recurrence was noted in only 2 of 17 patients whose desmoid tumors lacked trisomy 8. Our findings demonstrate that trisomy 8 and trisomy 20 are nonrandom aberrations in desmoid tumors. Trisomy 8 appears to be associated with an increased risk of recurrence.

Characteristic chromosome abnormalities and karyotype profiles in soft tissue tumors

Characteristic chromosome abnormalities and karyotype profiles are emerging for the soft tissue tumors. The notable findings are summarized in the Table 1. Within the broad range of solid tumors, it is certainly the soft tissue tumors in which the most spectacular success has occurred with regard to neoplasia-associated chromosome abnormalities. Cytogenetic studies of soft tissue tumors have been encouraged by the early and growing supporting interest of pathologists and clinicians concerned with soft tissue tumors. However, when one considers the variety of types and subtypes of benign and malignant soft tissue tumors, the number that has been so far characterized by a specific chromosome change is still very small. But, as we attempt to demonstrate in this report, these data should be viewed as paradigms for the importance of cytogenetic investigations in solid tumors. Cytogenetic studies of solid tumors are of more than clinical interest. Cytogenetic studies allow molecular investigations of the chromosomal breakpoints. They allow the search to proceed for genes involved in the chromosomal changes, providing a better knowledge of the malignant transformation process. In addition, the fruits of the combined efforts in cytogenetic and molecular technologies, from which has come "molecular cytogenetics," will let us recognize more conveniently, more quickly and, hopefully, less expensively the well-characterized diagnostic chromosome markers in tumor cells. Thus, we may be able to reach the goal of incorporating cytogenetics into standard diagnostic procedures for solid tumors, as has been achieved with hematological malignancies. Molecular cytogenetics including fluorescent in situ hybridization (FISH) technology promises to bring soft tissue tumor cytogenetics into regular diagnostic armamentaria and concurrently speed research into the basis of soft tissue tumors.

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.

Deletion (5q) in a desmoid tumor of a patient with Gardner's syndrome

Desmoid tumors are associated with as many as 20% of cases of familial adenomatous polyposis (FAP) and Gardner's syndrome. In the present study, four specimens from different regions of a massive intraabdominal desmoid tumor from a 23-year-old white male with Gardner's syndrome were analyzed cytogenetically. Two different clonal abnormalities were observed. Two of the four specimens analyzed showed a del(5)(q14q31), which involves the region q21-->22 where the familial adenomatous polyposis gene is localized. In the two other specimens, a balanced translocation involving chromosomes 3 and 4 and an inv(4) was detected. Our findings confirm previous reports about the importance of chromosome defects on 5q in development of desmoid tumors, particularly in patients with Gardner's syndrome.

Some desmoid tumors are characterized by trisomy 8

Ten desmoid tumors were examined by chromosome banding analysis and by in situ hybridization on short-term cultures and frozen sections. Trisomy 8 was detected in four out of ten tumors, of which only one had shown trisomy 8 by karyotype analysis. Since trisomy 8 has been reported in superficial fibromatoses, which are clinically distinct but histologically similar to desmoid tumors, the occurrence of trisomy 8 in both may be a further indication of a close relationship.

Chromosome aberrations in tenosynovial giant cell tumors and nontumorous synovial tissue

Five tenosynovial giant cell tumors--4 pigmented villonodular synovitis (PVNS) and 1 nodular tenosynovitis (NTS)--were investigated cytogenetically. Clonal chromosome aberrations were detected in 3 of them. One PVNS had t(7;16)(q22;q24) as the sole anomaly, whereas 1 PVNS and the NTS displayed aberrations suggesting clonal evolution: t(1;19)(p11;p12)/t(1;19), +12 and ins(5;1)(q31p34)/ins(5;1),t(2;4)(p23;q21), respectively. Including our 3 cases, a total of 6 tenosynovial giant cell tumors with karyotypic changes have been reported. Apart from 2 PVNS with trisomies 5 and 7, and 2 NTS with rearrangement of chromosome band 1p13, no recurrent chromosome change has been detected. Although the detection of clonal, acquired chromosome abnormalities has formerly generally been accepted as sufficient to conclude that a lesion is neoplastic, the interpretation of the pathogenetic significance of the karyotypic aberrations in synovial tumors is obscured by the fact that we have also detected comparable aberrations in obviously nonneoplastic synovial tissue. One of 2 lesions from patients with hemorrhagic synovitis carried a clonal del(13)(q12q21), and 2 of 4 synovectomy samples from patients with rheumatoid arthritis displayed -Y and -Y together with +7. The available cytogenetic data therefore cannot be used to resolve the controversy as to whether tenosynovial giant cell tumors are truly neoplastic or only reactive, inflammatory proliferations.

Clonal chromosomal abnormalities in desmoid tumors. Implications for histopathogenesis

Desmoid tumors (aggressive fibromatosis) are regarded as lesions of uncertain histopathogenesis. Cytogenetic analyses of 26 desmoid tumor specimens from abdominal or extraabdominal sites of 22 patients with or without Gardner's syndrome (GS) showed clonal karyotypic abnormalities in 7 cases, random abnormalities in 14 cases, and striking telomeric fusion in 5 cases. Loss of chromosome Y, a reported feature of fibromatosis in penile and palmar locations, was detected as a clonal aberration in two patients. Additionally, involvement of 5q was observed in six patients, two of whom had GS. Clonal interstitial deletions of 5q were observed in three patients, one with and two without GS. These findings confirm a clonal and probable neoplastic origin for desmoid tumor and suggest that abnormalities of the Y chromosome and 5q may be important in the genesis of this neoplasm.

Chromosome changes in desmoid tumors developed in patients with familial adenomatous polyposis

Chromosome analyses were performed on benign desmoid tumors obtained from two female patients with familial adenomatous polyposis (FAP), one of whom was diagnosed as having Gardner syndrome (GS). The modal chromosome number was 46 in both specimens, and detailed Q-banding analysis in Case 1 (GS) revealed a clonal abnormality of an interstitial deletion of the long arm of chromosome 5, del(5)(q21q31). The deleted region included an assigned locus for an FAP major gene (5q21-q22). All of the metaphases analyzed in this case showed an extra segment of bright fluorescence on the short arm of chromosome 15, but this unusual chromosome (15p+) was observed in both peripheral lymphocyte and skin fibroblast cultures from the patient, indicating that the 15p+ was constitutional in nature. In Case 2, no clonal rearrangements were identified and most cells had a normal karyotype. However, two cells showed rearrangements involving a 17q with non-identical breakpoints, one of which was observed as a solitary chromosome change. Based on the present findings in Case 1 and those reported so far, the chromosomal defect on 5q might be one of the causal genetic events primarily associated with the development of both benign desmoid tumors and colorectal adenomas and carcinomas in FAP patients.

Complex cytogenetic changes in benign neoplasms. Report of six lipomas

We report the detailed cytogenetic findings from short-term cultures of six lipomas with complex chromosomal abnormalities. In all six cases, the abnormality occurred in two stages; an initial inversion, translocation, or insertion of the involved chromosome(s) followed by a subsequent rearrangement of the resultant derivative chromosome(s). A striking feature of these rearrangements was the consistent involvement of bands q13 - q14 on chromosome 12 in all the abnormalities. This region has been shown to be specifically rearranged in most of the lipomas studied. The other chromosomes involved in the rearrangements were chromosomes 1 in four cases, 5 and 9 in two cases each, and 2, 3, 4, 7, and 10 in one case each. Our findings and published findings show that, with a few exceptions, benign tumors that were previously considered cytogenetically normal, are characterized not only by specific numerical and structural changes but may also contain complex chromosome rearrangements that are generally considered a hallmark of advanced malignancy. In benign tumors, this suggests that the genes at the region of the breakpoints may represent proliferation-related genes or that benign tumors with such complex aberrations represent neoplasms potentially capable of undergoing transformation to malignancy, or both.