Telomere biology in giant cell tumour of bone

Giant cell tumour of bone (GCTB) is a benign bone tumour known for the unpredictable clinical behaviour of recurrences and, in rare instances, distant metastases. It consists of uniformly distributed osteoclastic giant cells in a background of mononuclear rounded and spindle-shaped cells. Cytogenetically, telomeric associations are the most common chromosomal aberrations, which, however, are normally almost exclusively found in high-grade malignancies. GCTB has often been regarded as a polyclonal tumour, but more recently a recurrent specific aberration was reported, which suggests a possible role for disturbed telomere maintenance. Here we further investigate telomere maintenance in GCTB using 19 samples from 19 patients. A combination of immunofluorescence and FISH was performed, applying antibodies directed against promyelocytic leukaemia body-related antigen and hTERT and using telomere peptide nucleic acid probes. The TRAP assay and telomere restriction fragment length analysis were performed for functional detection of telomerase activity and alternative telomere lengthening. Both osteoclastic giant cells and mononuclear cells showed positivity for hTERT and promyelocytic leukaemia body-related antigen. In most mononuclear cells, co-expression was present. The TRAP assay demonstrated heterogeneous telomerase activity, while telomere restriction fragment length analysis showed non-heterogeneous telomere lengths, indicating the absence of alternative telomere lengthening. Confocal microscopy showed stereometric co-localization of nucleolin with promyelocytic leukaemia body-related antigen in association with telomeres in the spindle-shaped cells. hTERT was more diffusely distributed throughout the nucleus. Our results show that GCTB demonstrates remarkable telomere maintenance of activated telomerase and inactivated alternative telomere lengthening in the presence of normal mean telomere restriction fragment lengths. These findings strongly suggest that these aggregates, while activating telomerase, are part of a structural telomere protective-capping mechanism rather than of a telomere-lengthening mechanism. Telomere maintenance could be considered an important key factor in the pathogenesis of GCTB.

A 5-year follow-up study after knee disarticulation in two cases of Gollop-Wolfgang complex

The Gollop-Wolfgang Complex is a very rare anomaly, which has its essential features in congenital absence of the tibia and ipsilateral bifurcation of the femur. Surgical treatment of two patients with a follow-up of 5 years is reported.

MR imaging characteristics in primary lymphoma of bone with emphasis on non-aggressive appearance

PURPOSE

To assess the heterogeneity of magnetic resonance (MR) imaging characteristics in primary lymphoma of bone (PLB), in particular the non-aggressive appearance.

SUBJECTS AND METHODS

In a retrospective study, MR imaging features were analyzed in 29 patients with histologically proven PLB. The following parameters were evaluated: tumor size, bone marrow and extension into soft tissues, signal characteristics of bone marrow and soft-tissue components, including enhancement, and involvement of cortical bone (complete disruption, focal destruction, permeative destruction and cortical thickening).

RESULTS

PLB presented with extension into the soft tissue in 22 (76%) of 29 patients, was only subtle in three of these 22 patients, and was absent in seven patients. Signal intensity (SI) of the soft-tissue part was most frequently homogeneously isointense with muscle on T1-weighted images (90%) and high on T2-weighted images (91%). Enhancement was predominantly homogeneous and diffuse (82%). In 93% of patients cortical bone appeared abnormal: among those patients complete cortical disruption was seen in 28%, with extension into soft tissues in all but one patient; a permeative pattern of destruction was present in 52% of patients, 66% of these had an associated soft-tissue mass. Two patients with normal-appearing cortical bone had no extension into soft tissues. In two patients focal cortical destruction was noticed; in one patient cortical bone was homogeneously thickened, and in one patient PLB was selectively localized within the cortical bone. SI of the bone marrow tumor component was more frequently heterogeneous (in 54%), compared with the soft-tissue component, being high on T2-weighted images in 89%, intermediate in 7% and low in 4%. Similarly, enhancement was heterogeneous in 59%.

CONCLUSION

The MR imaging appearance of PLB is variable. In 31% of PLB patients, the tumor was intra-osseous, with linear cortical signal abnormalities or even normal-appearing or thickened cortical bone without soft-tissue mass, and, as such, PLB may not infrequently look non-aggressive on MR imaging.

The role of noncartilage-specific molecules in differentiation of cartilaginous tumors: lessons from chondroblastoma and chondromyxoid fibroma

BACKGROUND

Chondroblastoma (CB) and chondromyxoid fibroma (CMF) are benign tumors of bone morphologically recapitulating cartilage differentiation. CMF can resemble high-grade central chondrosarcoma (HGCCS) because of its cellular atypia. The mechanism that drives this morphologic spectrum of cartilage differentiation is unclear.

METHODS

CMFs and CBs were hybridized on a complementary DNA microarray that was enriched for cartilage-specific genes. Data were analyzed by Linear Model for Microarray Analysis and were compared with previous data on osteochondromas and HGCCS. Verification was performed in an extended series.

RESULTS

None of the 68 genes that were differentially expressed in CB versus CMF, including several extracellular matrix (ECM) and ECM-degradation genes, were related specifically to cartilage. Perlecan, versican, collagen 4A2 (Col4A2), and cell-cell adhesion genes, such as CD166, were significantly higher in CMF. Sixty genes were expressed differentially in CMF versus HGCCS. Higher expression levels of CD166, cyclin D1 (CCND1), and p16INK4A were observed in CMF.

CONCLUSIONS

The current findings indicated that differential expression of adhesion and ECM molecules, such as CD166, versican, perlecan, and Col4A2, may interfere with cartilaginous differentiation. The decreased expression of CCND1, p16INK4A, and CD166 in HGCCS reflects impairment of cell cycle progression and of cell-cell adhesions in malignant tumors and is of use in the differential diagnosis of CMF.

Decreased EXT expression and intracellular accumulation of heparan sulphate proteoglycan in osteochondromas and peripheral chondrosarcomas

Mutational inactivation of EXT1 or EXT2 is the cause of hereditary multiple osteochondromas. These genes function in heparan sulphate proteoglycan (HSPG) biosynthesis in the Golgi apparatus. Loss of heterozygosity of the EXT1 locus at 8q24 is frequently found in solitary osteochondromas, whereas somatic mutations are rarely found. We investigated the expression of EXT1 and EXT2 (quantitative RT-PCR) and of different HSPGs (immunohistochemistry) in solitary and hereditary osteochondromas and in cases with malignant progression to secondary peripheral chondrosarcoma, in relation to possible mutations and promoter methylation. The mutation status of patients with multiple osteochondromas correlated with decreased EXT1 or EXT2 expression found in their resected tumours. We could not show somatic point mutations or promoter hypermethylation in 17 solitary tumours; however, EXT1 expression was decreased in 15 cases, whereas EXT2 was not. Intracellular accumulation of syndecan-2 and heparan sulphate-bearing isoforms of CD44 (CD44v3) was found in most tumours, which concentrated in the Golgi apparatus as shown by confocal microscopy. This contrasted with the extracellular expression found in normal growth plates. In conclusion, mutational inactivation of either EXT1 or EXT2 leads to loss of mRNA expression of the corresponding gene. We hypothesize that loss of EXT expression disrupts the function of the EXT1/2 complex in HSPG biosynthesis, resulting in the intracellular accumulation of HSPG core proteins that we found in these tumours.

The role of EXT1 in nonhereditary osteochondroma: identification of homozygous deletions

BACKGROUND

Multiple osteochondromas is a hereditary syndrome that is characterized by the formation of cartilage-capped bony neoplasms (osteochondromas), for which exostosis (multiple)-1 (EXT1) has been identified as a causative gene. However, 85% of all osteochondromas present as solitary (nonhereditary) lesions in which somatic mutations in EXT1 are extremely rare, but loss of heterozygosity and clonal rearrangement of 8q24 (the chromosomal locus of EXT1) are common. We examined whether EXT1 might act as a classical tumor suppressor gene for nonhereditary osteochondromas.

METHODS

Eight nonhereditary osteochondromas were subjected to high-resolution array-based comparative genomic hybridization (array-CGH) analysis for chromosome 8q. The array-CGH results were validated by subjecting tumor DNA to multiple ligation-dependent probe amplification (MLPA) analysis for EXT1. EXT1 locus-specific fluorescent in situ hybridization (FISH) was performed on nuclei isolated from the three tissue components of osteochondroma (cartilage cap, perichondrium, bony stalk) to examine which parts of the tumor are of clonal origin.

RESULTS

Array-CGH analysis of tumor DNA revealed that all eight osteochondromas had a large deletion of 8q; five tumors had an additional small deletion of the other allele of 8q that contained the EXT1 gene. MLPA analysis of tumor DNA confirmed these findings and identified two additional deletions that were smaller than the limit of resolution of array-CGH. FISH analysis of the cartilage cap, perichondrium, and bony stalk showed that these homozygous EXT1 deletions were present only in the cartilage cap of osteochondroma.

CONCLUSION

EXT1 functions as a classical tumor suppressor gene in the cartilage cap of nonhereditary osteochondromas.

Improvement in histologic response but not survival in osteosarcoma patients treated with intensified chemotherapy: a randomized phase III trial of the European Osteosarcoma Intergroup

BACKGROUND

Previous randomized controlled trials that used the two-drug chemotherapy regimen of cisplatin and doxorubicin as the conventional arm showed no evidence of benefit from an increase in the number of agents or the length of treatment. It was then proposed that survival could be improved by increasing the planned dose intensity of cisplatin and doxorubicin.

METHODS

Previously untreated patients with nonmetastatic, high-grade, central osteosarcoma of an extremity were randomly assigned to Regimen-C (conventional treatment with six 3-week cycles of cisplatin [100 mg/m2 by 24-hour infusion] and doxorubicin [25 mg/m2/day by 4-hour infusion for 3 days]) or to Regimen-DI (intensified treatment with identical total doses of cisplatin and doxorubicin, planned as six 2-week cycles supported by granulocyte colony stimulating factor (G-CSF). Surgery was scheduled for week 6 in both arms. Primary and secondary outcome measures were overall and progression-free survival, respectively. Intention-to-treat analyses were performed using standard survival analysis methods. Landmark analyses were performed in patients with known surgical details and centrally reviewed histologic response. All statistical tests were two-sided.

RESULTS

Between May 1993 and September 2002, treatment was randomly allocated to 497 eligible patients. Six cycles of chemotherapy were completed by 78% of patients in Regimen-C and 80% of patients in Regimen-DI. The delivered preoperative median dose intensity of cisplatin was 86% in Regimen-C and 111% in Regimen-DI (as the percentage of that planned for the conventional regimen). Postoperative median dose intensity of cisplatin was 82% in Regimen-C and 110% in Regimen-DI (the corresponding figures for doxorubicin dose intensity were similar). Regimen-DI was associated with lower risks of severe leucopenia and neutropenia and higher risks of thrombocytopenia and mucositis. Good histologic response (>90% tumor necrosis) was observed in 36% of Regimen-C patients and 50% of Regimen-DI patients (P = .003, chi2 test). There was no evidence of a difference in overall survival (hazard ratio [HR] = 0.94, 95% CI = 0.71 to 1.24; P = .64) or progression-free survival (HR = 0.98, 95% CI = 0.77 to 1.24; P = .83). Landmark analyses showed similar results.

CONCLUSIONS

Planned intensification of chemotherapy with cisplatin and doxorubicin increased received dose intensity and resulted in a statistically significant increase in favorable histologic response rate, but not in increased progression-free or overall survival. Our results call into question the use of histologic response as a surrogate outcome measure in trials of this disease.

Peripheral chondrosarcoma progression is accompanied by decreased Indian Hedgehog signalling

Hedgehog (HH) signalling is important for specific developmental processes, and aberrant, increased activity has been described in various tumours. Disturbed HH signalling has also been implicated in the hereditary syndrome, Multiple Osteochondromas. Indian Hedgehog (IHH), together with parathyroid hormone-like hormone (PTHLH), participates in the organization of growth plates in long bones. PTHLH signalling is absent in osteochondromas, benign tumours arising adjacent to the growth plate, but is reactivated when these tumours undergo malignant transformation towards secondary peripheral chondrosarcoma. We describe a gradual decrease in the expression of Patched (PTCH) and glioma-associated oncogene homologue 1 (GLI1) (both transcribed upon IHH activity), and GLI2 with increasing malignancy, suggesting that IHH signalling is inactive and PTHLH signalling is IHH independent in secondary peripheral chondrosarcomas. cDNA expression profiling and immunohistochemical studies suggest that transforming growth factor-beta (TGF-beta)-mediated proliferative signalling is active in high-grade chondrosarcomas since TGF-beta downstream targets were upregulated in these tumours. This is accompanied by downregulation of energy metabolism-related genes and upregulation of the proto-oncogene jun B. Thus, the tight regulation of growth plate organization by IHH signalling is still seen in osteochondroma, but gradually lost during malignant transformation to secondary peripheral chondrosarcoma and subsequent progression. TGF-beta signalling is stimulated during secondary peripheral chondrosarcoma progression and could potentially regulate the retained activity of PTHLH.

Treatment of avascular necrosis of the hip by a non-vascularised cortical graft

This retrospective study describes the long-term results of core decompression and placement of a non-vascularised bone graft in the management of avascular necrosis of the femoral head. We treated 80 hips in 65 patients, 18 by a cortical tibial autograft and 62 by a fibular allograft. The mean age of the patients was 36 years (SD 13.2). A total of 78 hips were available for evaluation of which pre-operatively six were Ficat-Arlet stage 0, three stage I, 31 stage IIA, 16 stage IIB, 13 stage III and nine stage IV. A total of 34 hips (44%) were revised at a mean of four years (SD 3.8). Survivorship analysis using a clinical end-point showed a survival rate of 59% five years after surgery. We found a significant difference (p = 0.002) in survivorship, when using a clinical and radiological end-point, between the two grafts, in favour of the tibial autograft. We considered this difference to be the result of the better quality and increased volume of tibial bone compared with that from the trochanteric region used with the fibular allograft. This is a relatively simple, extra-articular and reproducible procedure. In our view core decompression, removal of the necrotic tissue and packing of the cancellous grafts into the core track are vital parts of the procedure.

Clinico-histologic parameters of osteosarcoma patients with late relapse

Primary high-grade intramedullary osteosarcoma of the extremities is a clinically aggressive bone tumour. There is an ongoing effort to further improve efficacy of neo-adjuvant chemotherapy and reduce chemotoxicity by trying to identify osteosarcoma patients who are at risk of treatment failure as well as to identify those who can do with less chemotherapy. In only 5% of patients, first distant metastasis or local relapse occurs 5 years or more after initial treatment for osteosarcoma. Patients and physicians can therefore easily erroneously consider a patient with osteosarcoma cured if he or she is disease-free for more than 5 years following diagnosis and treatment. To investigate if these rare late relapsing patients are characterised by specific clinico-pathological features, we examined clinical and histological variables of late relapse (first local recurrence or metastasis 5 years or more after initial diagnosis) out of a total of 2,243 patients, with a special interest in the histological osteosarcoma subtype. In total, 33 patients had a documented relapse 5 years or more after diagnosis. Half of the patients had good response (>or=90% necrosis) to pre-operative chemotherapy and the other half a poor response (<90% necrosis) and late relapses seemed to be more frequently proportionately in those who had a good initial response to chemotherapy. The occurrence of late relapse did not appear to be associated with age or gender. Although not statistically significant, there was a trend for patients with a chondroblastic subtype of osteosarcoma, or a location in the tibia or fibula, to have a higher risk for late relapse.

Array-comparative genomic hybridization of central chondrosarcoma

BACKGROUND

Enchondromas are benign lesions that can occur as solitary tumors or multiple tumors (Ollier disease) and may be precursors of central chondrosarcomas. Recurrent chondrosarcomas can be of a higher grade compared with primary tumors, suggesting possible progression.

METHODS

Genome-wide array-comparative genomic hybridization (CGH) was used to investigate copy number changes in enchondromas and central chondrosarcomas to elucidate both primary genetic events and the events related to tumor progression. Analyses of variance, Student t tests, and hierarchical clustering were used for the current analyses. Array-CGH data were compared with complementary DNA (cDNA) and quantitative reverse-transcriptase polymerase chain reaction expression array data.

RESULTS

Genomic imbalances were rare in enchondromas and in grade I chondrosarcomas, whereas they were frequent in high-grade tumors. No genomic imbalances that were specific for Ollier disease were found. The authors identified 22 chromosome regions that were imbalanced in > or =25% of tumors, and 3 of those regions were located on chromosome 12 (12p13, 12p11.21-p11.23, and 12q13, containing among others the PTPRF-interacting protein-binding protein 1 (PPFIBP1) gene. Loss of chromosome 6 and gain of 12q12 were associated with higher grade. Comparison of array-CGH with cDNA expression showed correlations for the ribosomal protein S6 (RPS6) and cyclin-dependent kinase 4 (CDK4) genes.

CONCLUSIONS

In the current study the authors identified genomic regions and new candidate genes (RPS6, CDK4, and PPFIBP1) that were associated with tumor progression and prognosis in patients with high-grade chondrosarcomas.

TGF-beta1 drives partial myofibroblastic differentiation in chondromyxoid fibroma of bone

Chondromyxoid fibroma (CMF) is a rare benign cartilaginous bone tumour with a lobular architecture containing stellate and myofibroblast-like spindle cells. The aim of this study was to investigate the presence, spatial distribution, and extent of myoid differentiation in CMF and to evaluate a possible causative role for TGF-beta1 signalling, which is known to promote smooth muscle actin (SMA) expression. Twenty cases were studied for immunoreactivity for muscle-specific actin (MSA), SMA, desmin, h-caldesmon, calponin, TGF-beta1, and plasminogen activator inhibitor type 1 (PAI-1). The extent of myofibroblastic differentiation was further investigated ultrastructurally, including immuno-electron microscopy using antibodies against MSA and SMA, focusing upon the different cell types in CMF. The expression of potential genes driving this process was quantified by Q-RT-PCR (TGF-beta1, fibronectin, its EDA splice variant, and PAI-1). Tumour cells, especially those with a spindled morphology, showed diffuse immunoreactivity for MSA, SMA, TGF-beta1, and PAI-1, while desmin, h-caldesmon, and calponin were absent. Ultrastructurally, neoplastic cells showed the presence of myofilaments and rare dense bodies, which were more prominent in spindle cells and less so in chondroblast-like cells. Immuno-electron microscopy confirmed the actin nature of these myofilaments. No fibronexus was identified. The functional activity of TGF-beta1 was demonstrated by the identification of PAI-1, a related downstream molecule both immunohistochemically as well as by Q-RT-PCR. There was a linear correlation between TGF-beta1 and PAI-1 expression. Fibronectin-EDA levels were low. We have therefore substantiated the presence of morphological, immunohistochemical, and immuno-electron microscopic partial myofibroblastic differentiation in CMF, driven by TGF-beta1 signalling.

Health-related quality of life and coping strategies of children after treatment of a malignant bone tumor: a 5-year follow-up study

PURPOSE

This study was designed to evaluate the development of health-related quality of life (HRQoL) and coping strategies of children and young adults, who have undergone surgery for a malignant bone tumor in childhood. PATIENTS AND INSTRUMENTS: In this single center follow-up study 20 patients were included. The patients were tested 3 and 8 years after treatment. At the 3-year mark the parents participated as well. To measure the HRQoL and coping strategies the TACQOL and the TAAQOL questionnaires and the Utrecht Coping List for Adolescents (UCLA) were used. All measurements were compared to a control group of healthy peers (n = 1,122 and n = 272, respectively).

RESULTS

At the first measurement (3 years after treatment) both the study patients and their parents reported significantly lower HRQoL scores on two domains: motor functioning and autonomy (P < 0.05). In addition parents reported their children to have significantly lower HRQoL scores on cognitive functioning and experiencing positive emotions. Five years later (8 years after treatment) the young adults reported comparable HRQoL on motor functioning and autonomy, and significantly higher HRQoL scores on cognitive functioning, social contacts and negative emotions (less depressive moods). With regard to coping strategies no significant differences between the two measurements in the study population and the reference group were found.

CONCLUSIONS

Three years after surgery for a malignant bone tumor, patients and their parents reported lower HRQoL scores on different domains compared with a reference group. Eight years after surgery the young adults surprisingly reported comparable or higher HRQoL scores. These patients treated for bone cancer were able to adapt well after treatment and showed no long-term emotional or social problems.

Epidiaphyseal versus other intercalary allografts for tumors of the lower limb

Epidiaphyseal intercalary reconstruction has become possible for bone tumors that extend into the epiphysis because advances in magnetic resonance imaging and chemotherapy allow close resection while sparing the juxtaarticular bone and joint. In a retrospective study, we questioned whether epidiaphyseal reconstructions around the knee had a clinical outcome (measured as long-term survival, complication rate, and functional score) comparable with metadiaphyseal and diaphyseal reconstructions. Between 1988 and 1999, 14 epidiaphyseal, nine metaphyseal, and 12 diaphyseal reconstructions were done, and the median followup was 7.2 years. Kaplan-Meier analysis showed a 10-year survival rate of 79% for epidiaphyseal reconstructions, which did not differ from an 89% rate for metadiaphyseal and a 75% rate for diaphyseal reconstructions. Epidiaphyseal complications included two infections, five fractures, and three nonunion treatments. Complications for all 35 grafts included three infections, 12 fractures, and nine nonunion treatments. Ultimately, six grafts failed, with infection and length of resection as predisposing factors. All epiphyseal osteotomies had tumor-free margins and no local recurrences. The mean Musculoskeletal Tumor Society score for each type of intercalary reconstruction was between 23 and 24. Because the epidiaphyseal reconstruction avoids complications associated with joint reconstruction and the results are comparable with those of other types of intercalary grafts, these reconstructions should be considered if at least 1 cm of tumor-free juxtaarticular bone can be maintained.

cDNA expression profiling of chondrosarcomas: Ollier disease resembles solitary tumours and alteration in genes coding for components of energy metabolism occurs with increasing grade

Conventional central chondrosarcomas are malignant cartilaginous tumours, occasionally arising secondary to either solitary or multiple (Ollier disease) enchondromas. Recurrences may have progressed in grade. The aims of the present study were to identify putative differences in gene expression between solitary and Ollier disease-related tumours, and to elucidate signalling pathways involved in tumour progression by genome-wide cDNA expression analysis. Arrays enriched for cartilage-specific cDNAs and genes involved in general tumourigenesis were used to analyse enchondromas (n = 3, two with Ollier disease), chondrosarcomas of different grades (n = 19, three with Ollier disease), normal resting-zone cartilage (n = 2), and chondrosarcoma cells in culture (n = 7). The arrays were analysed by unsupervised hierarchical clustering, significant analysis of microarray, and T-tests. Confirmation of data was performed by immunohistochemistry and quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Ollier disease cases and solitary tumours revealed similar expression profiles, suggesting that the same signalling pathways are involved in tumourigenesis. Interestingly, JunB protein expression was significantly higher in grade I chondrosarcomas than in enchondromas (p = 0.009), which could be of diagnostic relevance. Upon chondrosarcoma progression, matrix-associated genes are down-regulated, reflecting the histology of high-grade tumours. An increase in glycolysis-associated, and a decrease in oxidative phosphorylation-related, genes was found in high-grade tumours. These findings suggest an adaptation in energy supply upon progression towards higher grade.

Emerging pathways in the development of chondrosarcoma of bone and implications for targeted treatment

Chondrosarcoma is a malignant cartilage-forming tumour of bone, of which distinct clinicopathological subtypes are known. Conventional chondrosarcoma is notorious for its locally aggressive behaviour as well as for its resistance to chemotherapy and radiotherapy; so far surgery is the only effective therapeutic option. During the past 10 years, substantial new insights have been gained about molecular cell biology, molecular cytogenetics, and immunopathology, leading to better understanding of chondrosarcoma development at the molecular level, which will ultimately lead to better clinical understanding and possibly to the development of targeted treatment.

MRI of adamantinoma of long bones in correlation with histopathology

OBJECTIVE

The purposes of this retrospective study were to assess specific MRI features of adamantinoma, including classic adamantinoma and its osteofibrous dysplasia-like variant, and to assess the role of adamantinoma in surgical planning.

MATERIALS AND METHODS

MR images of 22 patients with histologically proven adamantinoma, subtyped according to defined criteria, were analyzed, with emphasis on morphologic features, signal intensities, and enhancement parameters. Intra- and extraosseous tumor extent was determined. In all patients, examination of the corresponding resected specimens was performed with regard to tumor extent and presence of multicentricity. Moreover, radiographs were reviewed, and radiographic features derived from the literature were determined.

RESULTS

All tumors were primarily localized in the tibia diaphysis (including one patient with additional lesions in the fibula), most frequently in the anterior cortical bone (19/22) with extension toward the bone marrow in 12 patients. We distinguished two morphologic patterns: a solitary lobulated focus versus a pattern of multiple small nodules in one or more foci. Separated tumor foci, defined as foci of high signal intensity on either T2-weighted images or T1-weighted contrast-enhanced images, interspersed with normal-appearing cortical or spongious bone were seen in six patients. All tumors showed intense and homogeneous static enhancement, but there was no uniform dynamic enhancement pattern. No relationship between MRI features and histologic subtype of adamantinoma was found.

CONCLUSION

Some uniform MRI characteristics, along with those of radiography, may contribute to the diagnosis of adamantinoma; however, these are not related to the histologic subtype. MRI is pivotal for precise locoregional staging, especially for depiction of distant cortical foci, soft tissue, and intramedullary extension and thus is useful for determining tumor-free margins and strategies for reconstructive surgery.

Chondromyxoid fibroma resemblesin vitro chondrogenesis, but differs in expression of signalling molecules

Chondromyxoid fibroma is a rare benign cartilaginous bone tumour characterized by morphological features that resemble different steps of chondrogenesis in terms of both cellular morphology, ranging from spindled to rounded cells, and the extracellular matrix formed, which ranges from fibrous to cartilaginous. The presence in chondromyxoid fibroma of signalling molecules that regulate the spatial expression of proteins involved in normal cartilage proliferation and differentiation was investigated in samples from 20 patients and compared with articular chondrocytes from 11 normal donors cultivated in 3D pellet culture. Sections were stained with safranin-O and H&E, and immunohistochemistry was performed for p16, cyclin D1, FGFR3, BCL2, p21, PTHLH, PTHR1 and N-cadherin. Expression patterns were analysed using hierarchical clustering. In chondromyxoid fibroma, specific morphological features correlated with a distinct pattern of expression. Comparison with normal chondrocytes in pellet culture showed a striking morphological resemblance, but with an unmistakably different pattern of expression. N-cadherin, PTHLH, and PTHR1 were expressed to a significantly higher level (p < 0.01) in articular chondrocyte pellets but, conversely, there was significantly lower expression of cyclin D1, p16 and BCL2 (p < 0.05) in these cells. Morphological similarities reflect common steps in cartilage differentiation, albeit driven by different molecular mechanisms. The proteins we have found to be differentially expressed seem crucial for neoplastic chondrogenesis.

Soft-Tissue Tumors: Value of Static and Dynamic Gadopentetate Dimeglumine–enhanced MR Imaging in Prediction of Malignancy

PURPOSE

To prospectively evaluate static and dynamic gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging relative to nonenhanced MR imaging in differentiation of benign from malignant soft-tissue lesions and to evaluate which MR imaging parameters are most predictive of malignancy, with associated interobserver variability.

MATERIALS AND METHODS

One hundred forty consecutive patients (78 male patients [median age, 51 years], 62 female patients [median age, 53 years]) with a soft-tissue mass underwent nonenhanced static and dynamic contrast material-enhanced MR imaging. Diagnosis was based on histologic findings in surgical specimens (86 of 140), findings at core-needle biopsy (43 of 140), or results of all imaging procedures with clinical follow-up (11 of 140). Multivariate logistic regression analysis was used to identify the best combination of MR imaging parameters that might be predictive of malignancy. Subjective overall performance of two observers was evaluated with receiver operating characteristic analysis.

RESULTS

For subjective overall diagnosis, area under the receiver operating characteristic curve, a measure for diagnostic accuracy, was significantly larger for combined nonenhanced and contrast-enhanced MR imaging than it was for nonenhanced MR imaging alone, with no significant difference between observers. Multivariate analysis of all lesions revealed that combined nonenhanced static and dynamic contrast-enhanced MR imaging parameters were significantly superior to nonenhanced MR imaging parameters alone and to nonenhanced MR imaging parameters combined with static contrast-enhanced MR imaging parameters in prediction of malignancy. The most discriminating parameters were presence of liquefaction, start of dynamic enhancement (time interval between start of arterial and tumor enhancement), and lesion size (diameter). Results for extremity lesions were the same, with one exception: With dynamic contrast-enhanced MR imaging parameters, diagnostic performance of one observer did not improve.

CONCLUSION

Static and dynamic contrast-enhanced MR imaging, when added to nonenhanced MR imaging, improved differentiation between benign and malignant soft-tissue lesions.

Overexpression of the HER-2 oncogene does not play a role in high-grade osteosarcomas

The aim of our study was to determine whether or not the tyrosine kinase receptor, HER2 (also known as ErbB2/Her2/neu), is overexpressed in human osteosarcomas (OS). We studied 15 biopsy and 18 resection specimens at the mRNA and protein levels. HER2 status in the OS specimens was assessed by immunohistochemistry (IHC) and quantitative Real-Time Polymerase chain reaction (PCR). In moderately immunopositive cases fluorescent in situ hybridisation (FISH) analysis was used in order to identify any possible gene amplification. 27 samples were evaluable for IHC and only 1 case showed a moderately positive membrane staining. The remaining samples showed no staining or focal cytoplasmic staining (2 samples). In the moderately positive case, FISH analysis showed no HER-2 gene amplification. There was also no overexpression of HER2 mRNA suggesting this sample was a false-positive immunostain. HER2 mRNA expression was present in all samples at a similar level to that in the breast cancer cell line, MCF7, which does not overexpress HER2 and was used as a negative control. In conclusion, this study shows that HER2 mRNA or membranous HER2 protein overexpression is absent in human OS. We noted various inconsistencies in previous published studies, with regard to methodology and the interpretation of the results based on poor methodology. We therefore conclude that the positive data with regard to HER2 overexpression reported in these previous studies is not reliable. Our results suggest that the monoclonal antibody trastuzumab (Herceptin(R)), directed against the HER2-receptor, is not likely to be an effective therapeutic agent in OS.

Molecular analysis of the INK4A/INK4A-ARF gene locus in conventional(central) chondrosarcomas and enchondromas: indication of an important gene for tumour progression

Loss of heterozygosity (LOH) at chromosomal band 9p21 is one of the few consistent genetic aberrations found in conventional chondrosarcoma. This locus harbours two cell-cycle regulators, CDKN2A/p16/INK4A and INK4A-p14ARF, which are inactivated in various human malignancies. It was therefore hypothesized that this locus also plays a role in the development of chondrosarcoma and this locus was investigated at protein, genetic, and epigenetic levels. Loss of p16 protein expression was detected by immunohistochemistry in 12 of 73 central chondrosarcomas and it correlated with increasing histological grade (p = 0.001). Loss of p16 protein expression was not found in 51 enchondromas, which are presumed to be potential precursors of conventional central chondrosarcoma. LOH at 9p21 was found in 15 of 39 chondrosarcomas (38%) but it did not correlate with loss of p16 protein expression. SSCP analysis of p16 did not reveal any mutations in 47 cases. Also, p14 was not the target of LOH, since it gave no aberrant bands on SSCP. To investigate whether an epigenetic mechanism was operating, methylation-specific PCR was used to look at p16 promotor methylation, which was identified in 5 of 30 tumours. However, this did not correlate with protein expression, or with LOH at 9p21. Cytogenetic data were available in a subset of cases. All tumours that showed chromosome 9 alterations also showed LOH and loss of INK4A/p16 protein expression. It is concluded that although some alterations were found at the DNA level and at the promoter expression level, the lack of correlation between LOH, promotor methylation, and protein expression indicates that a locus other than CDKN2A/p16 must be the target of LOH at 9p21. The correlation between INK4A/p16 protein expression and tumour grade, and the retention of expression in enchondromas, indicates that loss of INK4A/p16 protein expression may be an important event during tumour progression from enchondroma to conventional central chondrosarcoma, and in the progression in grade after recurrence of chondrosarcoma.

Expression of cartilage growth plate signalling molecules in chondroblastoma

Chondroblastoma (CB) is a rare benign tumour (<1% of all bone tumours) involving epiphyseal long bones (male:female 1.5:1). During development, and in the postnatal period, IHh/PTHrP and FGF signalling molecules control the space and timing of chondrocyte differentiation. Considering the close relationship of CB with the growth plate (age and location), the expression of proteins involved in epiphyseal growth regulation was studied. Twelve cases of CB were retrieved. Immunohistochemistry was performed using antibodies against fibroblast growth factor-2 (FGF-2), fibroblast growth factor receptor-1 (FGFR-1), FGFR-3, bcl-2, p21, parathyroid hormone-related peptide (PTHrP), and parathyroid hormone-related peptide receptor (PTHR1). Three observers evaluated haematoxylin and eosin (H&E)-stained and immunostained slides independently. Semi-quantitative estimation of the matrix, the type of matrix, and immunostaining was performed. Cellular and matrix-rich areas were evaluated separately. Diverse amounts and types of matrix were present in different tumours, as well as within individual tumours. Signalling molecules were expressed in 50-100% of the cases. Higher levels of expression were found in cellular areas than in matrix-rich areas, especially for PTHR1, bcl-2, and FGFR-3. CB is an unusual entity affecting specific sites, showing that both IHh/PTHrP and FGF signalling are active. Higher expression was found in cellular than in matrix-rich areas, as in the proliferating/pre-hypertrophic growth plate zone in comparison with the hypertrophic/calcifying zone. Previous studies have shown the same molecules to be expressed with a similar pattern in chondrosarcomas. The sum of the evaluated features indicates that CB is a neoplasm originating from a mesenchymal cell committed towards chondrogenesis via active growth plate signalling pathways.

Dynamic contrast-enhanced MR imaging in monitoring response to isolated limb perfusion in high-grade soft tissue sarcoma: initial results

The objective of this study was to evaluate whether dynamic contrast-enhanced MR imaging can determine tumor response and localize residual viable tumor after isolated limb perfusion (ILP) chemotherapy in soft tissue tumors. Twelve consecutive patients, with histologically proven high-grade soft tissue sarcoma, prospectively underwent non-enhanced MR and dynamic contrast-enhanced MR imaging before and after ILP. Tumor volume was measured on non-enhanced MR images. The temporal change of signal intensity in a region of interest on dynamic contrast-enhanced MR images was plotted against time. Start, pattern, and progression of enhancement were recorded. Histopathologic response was defined as complete response if no residual viable tumor was present, partial remission if <50% viable tumor was present, and no change if > or =50% viable tumor was present in the resection specimen. Resected specimens for correlation with histopathology were available for 10 patients; 5 patients had partial remission and 5 had no change. Volume measurements correctly predicted tumor response in 6 of 10 patients. Dynamic contrast-enhanced MR correctly predicted tumor response in 8 of 10 patients. Early rapidly progressive enhancement correlated histologically with residual viable tumor. Late and gradual, or absence of enhancement, was associated with necrosis, predominantly centrally located, or granulation tissue. These preliminary results show that dynamic contrast-enhanced MR imaging offers potential for non-invasive monitoring of response to isolated limb perfusion in soft tissue sarcomas due to identification of residual areas of viable tumor and subsequently may provide clinically useful information with regards to timing and planning of additional surgery. Further prospective studies in a larger patient population is warranted.

Expression of cell cycle-related gene products in Langerhans cell histiocytosis

BACKGROUND The pathogenesis of Langerhans cell histiocytosis (LCH), a disease characterized by an abnormal accumulation of the dendritic Langerhans cells, is still unknown. Based on the monoclonality of the CD1a+ cell and reports of familial clustering, it is hypothesized that a genetic alteration at a cellular level may be causative. This genetic change may have an effect on the cellular mechanisms controlling proliferation and apoptosis. MATERIALS AND METHODS LCH-lesions were studied for the expression of Ki-67, present in the nucleus of proliferating cells. Furthermore, the expression of cell cycle-related gene products TGF-beta receptor I and II, MDM2, p53, p21, p16, Rb, and Bcl2 were studied. The TGF-betaR genes play a role in tumor suppression, whereas Bcl2 inhibits apoptosis. The remaining genes are part of either the p53-p21 and/or p16-Rb pathways, which induce cell cycle arrest or apoptosis in response to DNA damage. RESULTS In 30 biopsies the diagnosis of LCH could be confirmed on the basis of CD1a positivity (27 bone and 3 skin). All cases showed scattered nuclear-positive staining for the proliferation marker Ki-67. In more than 90% (n >/=27) of these cases, expression of TGFbeta receptor I and II, MDM2, p53, p21, p16, Rb, and Bcl2 was detected in lesional LCH cells. The overexpression was in general heterogeneous, ranging from limited focal staining of scattered cells within the lesion to strong diffuse staining. CONCLUSIONS These findings suggest that the cellular mechanisms that sense and respond to DNA-damage, namely the p53-p21 pathway and the p16-Rb pathway, are activated. The expression of Ki-67 indicates that the cells in LCH are proliferating. The observed overexpression of Bcl2 may play a role in the activation of p53 and p16 and/or the arrest of apoptosis.