p53 expression and DNA ploidy of cartilage lesions

CD34+ synovial fibroblasts exhibit high osteogenic potential in synovial chondromatosis

Synovial chondromatosis (SC) is a disorder of the synovium characterized by the formation of osteochondral nodules within the synovium. This study aimed to identify the abnormally differentiated progenitor cells and possible pathogenic signaling pathways. Loose bodies and synovium were obtained from patients with SC during knee arthroplasty. Single-cell RNA sequencing was used to identify cell subsets and their gene signatures in SC synovium. Cells derived from osteoarthritis (OA) synovium were used as controls. Multi-differentiation and colony-forming assays were used to identify progenitor cells. The roles of transcription factors and signaling pathways were investigated through computational analysis and experimental verification. We identified an increased proportion of CD34+ sublining fibroblasts in SC synovium. CD34+CD31- cells and CD34-CD31- cells were sorted from SC synovium. Compared with CD34- cells, CD34+ cells had larger alkaline phosphatase (ALP)-stained area and calcified area after osteogenic induction. In addition, CD34+ cells exhibited a stronger tube formation ability than CD34- cells. Our bioinformatic analysis suggested the expression of TWIST1, a negative regulator of osteogenesis, in CD34- sublining fibroblasts and was regulated by the TGF-β signaling pathway. The experiment showed that CD34+ cells acquired the TWIST1 expression during culture and the combination of TGF-β1 and harmine, an inhibitor of Twist1, could further stimulate the osteogenesis of CD34+ cells. Overall, CD34+ synovial fibroblasts in SC synovium have multiple differentiation potentials, especially osteogenic differentiation potential, and might be responsible for the pathogenesis of SC.

Dedifferentiated Chondrosarcoma: Diagnostic Controversies and Emerging Therapeutic Targets

PURPOSE OF REVIEW

The pathogenesis of dedifferentiated chondrosarcoma is controversial, and no genetic abnormality has consistently been identified in the disease. Focusing on the diagnostic challenges encountered in dedifferentiated chondrosarcoma, the following review aims at summarizing the tumor's active neoplastic pathways while highlighting therapeutic modalities that could potentially be explored to enhance patient survivorship.

RECENT FINDINGS

Owing to the challenging examination of small needle biopsy sampling as well as the disease's overlapping morphological and immunohistochemical features with other bone and soft-tissue sarcomas, the diagnosis of dedifferentiated chondrosarcoma can be problematic. While combined doxorubicin- and cisplatin-based regimens remain the first-line systemic chemotherapy in the disease, ~50% of tumors carry EXT1/2 or IDH1/2 mutations, advancing EXT or IDH inhibitors as potential alternative therapies, respectively. Despite systemic chemotherapy, dedifferentiated chondrosarcoma remains an aggressive tumor with dismal prognosis and limited survival. A multidisciplinary collaboration across multiple cancer centers is warranted to yield an accurate diagnosis, understand the disease's underlying pathogenesis, develop adequate treatment, and improve patient survivorship.

Dedifferentiated Central Chondrosarcoma: A Clinical, Histopathological, and Immunohistochemical Analysis of 57 Cases

Dedifferentiated central chondrosarcoma (DCCS) is a rare cartilage tumor with invasive biological behavior and a poor prognosis. To better understand the morphological characteristics of this type of tumor and its internal mechanism of dedifferentiation, we retrospectively analyzed 57 cases of DCCS. A total of 29 female and 28 male patients were included, ranging in age from 20 to 76 years, with a median age of 54 years. Fifty-seven cases of DCCS occurred in the pelvis (n = 29), femur (n = 17), scapula (n = 4), tibia (n = 2), humerus (n = 2), metatarsals (n = 1), fibula (n = 1), and radius (n = 1). Radiologically, DCCS had two different appearances on imaging, with an area showing calcifications of the cartilage forming the tumor juxtaposed to a lytic area with a highly aggressive, non-cartilaginous component. Histopathologically, the distinctive morphological features consisted of two kinds of defined components: a well-differentiated cartilaginous tumor and non-cartilaginous sarcoma. The cartilaginous components included grade 1 (n = 38; 66.7%) and grade 2 (n = 19; 33.3%) cartilage. The sarcoma components included those of osteosarcoma (n = 29; 50.9%), undifferentiated pleomorphic sarcoma (n = 20; 35.1%), rhabdomyosarcoma (n = 3; 5.2%), fibrosarcoma (n = 2; 3.5%), spindle cell sarcoma (n = 2; 3.5%) and angiosarcoma (n = 1; 1.8%). Immunohistochemistry showed that the expression of p53 and RB in the sarcoma components was significantly higher than that in the cartilaginous components, suggesting that these factors play roles in the dedifferentiation process of chondrosarcoma. DCCS is a highly malignant tumor with a poor prognosis. Except for the patients who were lost to follow-up, most of our patients died.

Sacral chondroblastoma — a rare location, a rare pathology: A case report and review of literature

BACKGROUND

Chondroblastoma (CB) is an intermediate tumor of cartilage origin. CB involving the sacrum is a very rare pathology.

CASE SUMMARY

A 17-year-old male with sacral CB was diagnosed as CB during the first surgery, and 18 mo later, the tumor recurred and a second surgery was performed with the same pathology result of CB.

CONCLUSION

We recommend complete removal of the tumor in a timely manner, provided that surgical conditions are met. At the same time, other diseases should be carefully differentiated in terms of imaging or pathological features so as to avoid erroneous diagnostic conclusions.

SOX9 Knockout Induces Polyploidy and Changes Sensitivity to Tumor Treatment Strategies in a Chondrosarcoma Cell Line

As most chemotherapeutic drugs are ineffective in the treatment of chondrosarcoma, we studied the expression pattern and function of SOX9, the master transcription factor for chondrogenesis, in chondrosarcoma, to understand the basic molecular principles needed for engineering new targeted therapies. Our study shows an increase in SOX9 expression in chondrosarcoma compared to normal cartilage, but a decrease when the tumors are finally defined as dedifferentiated chondrosarcoma (DDCS). In DDCS, SOX9 is almost completely absent in the non-chondroid, dedifferentiated compartments. CRISPR/Cas9-mediated knockout of SOX9 in a human chondrosarcoma cell line (HTB94) results in reduced proliferation, clonogenicity and migration, accompanied by an inability to activate MMP13. In contrast, adhesion, apoptosis and polyploidy formation are favored after SOX9 deletion, probably involving BCL2 and survivin. The siRNA-mediated SOX9 knockdown partially confirmed these results, suggesting the need for a certain SOX9 threshold for particular cancer-related events. To increase the efficacy of chondrosarcoma therapies, potential therapeutic approaches were analyzed in SOX9 knockout cells. Here, we found an increased impact of doxorubicin, but a reduced sensitivity for oncolytic virus treatment. Our observations present novel insight into the role of SOX9 in chondrosarcoma biology and could thereby help to overcome the obstacle of drug resistance and limited therapy options.

A molecular study of synovial chondromatosis

Synovial chondromatosis (SC) is a rare benign cartilaginous neoplasm in which recurrent fibronectin 1 (FN1) and activin receptor 2A (ACVR2A) gene rearrangements have been recently reported. Triggered by a case of malignant transformation in SC (synovial chondrosarcoma) showing a novel KMT2A-BCOR gene fusion by targeted RNA sequencing, we sought to evaluate the molecular abnormalities in a cohort of 27 SC cases using a combined methodology of fluorescence in situ hybridization (FISH) and/or targeted RNA sequencing. Results showed that FN1 and /or ACVR2A gene rearrangements were noted in 18 cases (67%), with an FN1-ACVR2A fusion being confirmed in 15 (56%) cases. Two cases showed only FN1 gene rearrangement, without other abnormalities. A novel FN1-NFATc2 gene fusion was noted in one case by RNA sequencing. The remaining nine cases showed no abnormalities in FN1 and ACVR2A genes. No additional cases showed BCOR gene alterations. In conclusion, this study confirms that FN1-ACVR2A fusion is the leading pathogenetic event in SC, at even higher frequency than previously reported. FISH methodology emerges as an appropriate tool in the identification of FN1 and ACVR2A gene abnormalities, which can be used in challenging cases. Further studies are needed to determine the recurrent potential of BCOR abnormalities in this disease.

Targeted next-generation sequencing of dedifferentiated chondrosarcoma in the skull base reveals combined TP53 and PTEN mutations with increased proliferation index, an implication for pathogenesis

Dedifferentiated chondrosarcoma (DDCS) is a rare disease with a dismal prognosis. DDCS consists of two morphologically distinct components: the cartilaginous and noncartilaginous components. Whether the two components originate from the same progenitor cells has been controversial. Recurrent DDCS commonly displays increased proliferation compared with the primary tumor. However, there is no conclusive explanation for this mechanism. In this paper, we present two DDCSs in the sellar region. Patient 1 exclusively exhibited a noncartilaginous component with a TP53 frameshift mutation in the pathological specimens from the first surgery. The tumor recurred after radiation therapy with an exceedingly increased proliferation index. Targeted next-generation sequencing (NGS) revealed the presence of both a TP53 mutation and a PTEN deletion in the cartilaginous and the noncartilaginous components of the recurrent tumor. Fluorescence in situ hybridization and immunostaining confirmed reduced DNA copy number and protein levels of the PTEN gene as a result of the PTEN deletion. Patient 2 exhibited both cartilaginous and noncartilaginous components in the surgical specimens. Targeted NGS of cells from both components showed neither TP53 nor PTEN mutations, making Patient 2 a naïve TP53 and PTEN control for comparison. In conclusion, additional PTEN loss in the background of the TP53 mutation could be the cause of increased proliferation capacity in the recurrent tumor.

Both a visual and a semiquantitative analysis for differentiating benign from malignant chondrogenic bone tumors using Tc-99m (V) DMSA scintigraphy: a prospective study

OBJECTIVE

The aims of this prospective study were to assess the relationship between tumor aggressiveness and Tc-99m (V) dimercaptosuccinic acid (DMSA) uptake in chondrogenic bone tumors and the value of Tc-99m (V) DMSA scintigraphy for differentiating benign from malignant tumors.

METHODS

Twenty-four patients with chondrogenic tumors (19 benign and five malignant) underwent Tc-99m DMSA (V) scintigraphy. Radiopharmaceutical uptake was classified using a three-point scale to allow a visual-only analysis, and a tumor-to-background contrast (TBC) was computed using regions of interest to provide a semiquantitative analysis. Spearman's correlation coefficient was used to assess the correlation between tumor aggressiveness and TBC. The difference in TBC between benign and malignant tumors was analyzed with the Mann-Whitney U-test. An appropriate cutoff value of TBC was chosen for the diagnosis of malignancy of a tumor using receiver operating characteristic analysis.

RESULTS

Six benign tumors showed negative uptake (uptake score 0), whereas 13 benign tumors showed positive uptake (n=10 uptake score 1; n=3 uptake score 2). All chondrosarcomas showed positive uptake (n=2 uptake score 1; n=3 uptake score 2). A significant correlation was found between tumor aggressiveness and TBC. A significant difference was seen in TBC between benign and malignant tumors. With the chosen cutoff value of TBC equal to 0.611, the sensitivity was 80.0%, specificity was 78.9%, the positive predictive value was 50.0%, and the negative predictive value was 93.8%.

CONCLUSION

Tc-99m (V) DMSA scintigraphy may have the potential to improve diagnostic methods for detecting chondrosarcomas using visual and/or semiquantitative analyses.

Genetic alterations in chondrosarcomas - keys to targeted therapies?

BACKGROUND

Chondrosarcomas are malignant tumors of chondrocytes and represent the second most common type of primary bone tumors. Within the context of normal chondrogenesis, this review summarizes results from recent research outlining the key molecular changes that occur during the development of this sarcoma type.

RESULTS

Current data support the notion that a two-hit scenario, common to many tumors, also underlies chondrosarcoma formation. First, early-stage mutations alter the normal proliferation and differentiation of chondrocytes, thereby predisposing them to malignant transformation. These early-stage mutations, found in both benign cartilaginous lesions and chondrosarcomas, include alterations affecting the IHH/PTHrP and IDH1/IDH2 pathways. As they are not observed in malignant cells, mutations in the EXT1 and EXT2 genes are considered early-stage events providing an environment that alters IHH/PTHrP signaling, thereby inducing mutations in adjacent cells. Due to normal cell cycle control that remains active, a low rate of malignant transformation is seen in benign cartilaginous lesions with early-stage mutations. In contrast, late-stage mutations, seen in most malignant chondrosarcomas, appear to induce malignant transformation as they are not found in benign cartilaginous lesions. These late-stage mutations primarily involve cell cycle pathway regulators including p53 and pRB, two genes that are also known to be implicated in numerous other human tumor types.

CONCLUSIONS

Now the key genetic alterations involved in both early and late stages of chondrosarcoma development have been identified, focus should be shifted to the identification of druggable molecular targets for the design of novel chondrosarcoma-specific therapies.

Genetic characterization of mesenchymal, clear cell, and dedifferentiated chondrosarcoma

Clear cell, mesenchymal, and dedifferentiated chondrosarcoma are rare, cartilaginous tumors with limited treatment options other than surgery. Conventional chondrosarcomas have been extensively studied at the genetic level, but for rare chondrosarcoma subtypes, this is merely restricted to case reports. Information on the genetics of rare chondrosarcomas may provide insight into the etiology of these specific disease subtypes and possible alternative treatment strategies. Therefore, the aim of this study was to genetically characterize this subset of rare tumors. Using array CGH, we gathered genomic information of 30 rare cartilaginous tumors. In addition, we constructed tissue microarrays with 2 mm cores of 23 clear cell, 23 mesenchymal, and 45 dedifferentiated chondrosarcomas, in triplicate. Using immunohistochemistry, we investigated expression of R132H IDH1, and p53 and retinoblastoma pathways. Results were verified and further investigated with a methylation assay and MLPA for CDKN2A/p16, and IDH1/2, and TP53 mutation analysis. Array-CGH showed numerous genomic alterations in all subtypes. However, only a limited number of recurrent alterations were detected, none of which seemed to be associated with the subtypes. The IDH1/2, p53, and retinoblastoma pathways were affected in 0, 9, and 95% of clear cell chondrosarcomas, in 0, 39, and 70% in mesenchymal chondrosarcomas, and in 50, 59, and 85% of dedifferentiated chondrosarcomas, respectively. Our results suggest an important role for the retinoblastoma pathway in all three rare chondrosarcoma subtypes investigated.

Clinical and histopathological prognostic factors in chondrosarcomas

Purpose. In an attempt to identify clinical and histopathological factors of prognostic importance in chondrosarcomas, 115 cases of malignant and borderline chondromatous tumours were reviewed.

Patients/methods. Histopathological features tested for prognostic information as well as reproducibility included cellularity, nuclear pleomorphism, multinucleated cells, mitotic activity and grade. Eleven patients had a biopsy only, and a short survival (median 2.0 years); these were excluded from further analysis. The remaining 104 patients who had received intended curative treatment had a median survival of 14.7 years.

Results. In univariate analysis, tumour size, extra-compartmental growth, surgical margin and sex were significantly correlated to recurrence-free survival (RFS); sex was marginally significant while age, site and pathological parameters were not significant. Overall survival (OAS) was likewise found to be independent of pathological features as well as site, size and surgical margin; but age, sex and extra-compartmental growth were statistically significant. However, when the same parameters were entered into a stepwise Cox (multivariate) analysis, only surgical margin, cellularity and pleomorphism were significantly related to RFS; margin, grade, pleomorphism and age to OAS. Overall inter-observer agreement on grade was relatively low: 0.54, with a Kappa value of 0.32. It was not better for the other histological parameters, with the exception of the mitotic count. However, acceptable values were achieved when the material was divided into low-grade (grade I and below) vs high-grade (grade II and III) lesions: overall agreement 0.79, Kappa 0.56.

Discussion. Although the grading of chondrosarcomas is in need of improvement, its replacement by semiquantitative evaluation of individual histopathological parameters as performed in this study offers no advantage. Among the clinical parameters, only the adequacy of the surgical treatment and the patient's age appear to be important.

Chondrosarcoma and peroxisome proliferator-activated receptor

Induction of differentiation and apoptosis in cancer cells by ligands of PPARγ is a novel therapeutic approach to malignant tumors. Chondrosarcoma (malignant cartilage tumor) and OUMS-27 cells (cell line established from grade III human chondrosarcoma) express PPARγ. PPARγ ligands inhibited cell proliferation in a dose-dependent manner, and induced apoptosis of OUMS-27. The higher-grade chondrosarcoma expressed a higher amount of antiapoptotic Bcl-xL in vivo. The treatment of OUMS-27 by 15d-PGJ₂, the most potent endogenous ligand for PPARγ, downregulated expression of Bcl-xL and induced transient upregulation of proapoptotic Bax, which could accelerate cytochrome c release from mitochondria to the cytosol, followed by induction of caspase-dependent apoptosis. 15d-PGJ₂ induced the expression of CDK inhibitor p21 protein in human chondrosarcoma cells, which appears to be involved in the mechanism of inhibition of cell proliferation. These findings suggest that targeted therapy with PPARγ ligands could be a novel strategy against chondrosarcoma.

The clinical relevance of molecular genetics in soft tissue sarcomas

Bone and soft tissue sarcomas are an infrequent and heterogeneous group of mesenchymal tumors including more than a hundred different entities attending to histologic patterns. Research into the molecular aspects of sarcomas has increased greatly in the last few years. This enormous amount of knowledge has allowed, for instance, to refine the classification of sarcomas, improve the diagnosis, and increase the number of therapeutical targets available, most of them under preclinical evaluation. However, other important key issues, such as sarcomagenesis and the cell of origin of sarcomas, remain unresolved. From a molecular point of view, these neoplasias are grouped into 2 main types: (a) sarcomas showing relatively simple karyotypes and translocations, which originate gene fusions (eg, EWS-FLI1 in Ewing sarcoma) or point mutations (eg, c-kit in the gastrointestinal tumors) and (b) sarcomas showing unspecific gene alterations, very complex karyotypes, and no translocations. The discovery of the early mechanisms involved in the genesis of sarcomas, the more relevant signaling pathways, and the development of genetically engineered mouse models could also provide a new individualized therapeutic strategy against these tumors. This review describes the clinical application of some of the molecular alterations found in sarcomas, some advances in the field of sarcomagenesis, and the development of animal models.

Extended intralesional treatment versus resection of low-grade chondrosarcomas

The need for segmental resection versus intralesional treatment of low-grade chondrosarcomas of the appendicular skeleton remains controversial. We hypothesized extended intralesional treatment would equally control malignant disease but with improved functional outcomes and decreased postoperative complications. We retrospectively reviewed 31 patients with 32 Grade I intracompartmental chondrosarcomas of the long bones of the appendicular skeleton treated with either resection (15 lesions) or extended intralesional curetting (17) at a minimum followup of 2 years (median, 55 months; range, 24-203 months). Lesions were larger and median followup was longer in the resection cohort. One local recurrence developed in each treatment cohort and neither transitioned to a higher grade of tumor. No patient had metastases develop or died of disease. The mean final Musculoskeletal Tumor Society functional scores were greater after extended intralesional versus resection treatment (29.5 versus 25.1). Complications were observed more frequently after resection and reconstruction (seven of 15) as compared with extended intralesional treatment (one of 17). Extended intralesional treatment of Grade I intracompartmental chondrosarcomas of the long bones of the appendicular skeleton therefore appears safe with improved functional scores and decreased complications versus segmental resection and reconstruction.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The clinical approach towards chondrosarcoma

This review provides an overview of the histopathology, classification, diagnostic procedures, and therapy of skeletal chondrosarcoma. Chondrosarcomas that arise de novo are primary chondrosarcomas, whereas chondrosarcomas developing superimposed on pre-existing benign cartilage neoplasms such as enchondromas or osteochondromas are referred to as secondary chondrosarcomas. Conventional chondrosarcomas can be categorized according to their location in bone into central, peripheral, and juxtacortical chondrosarcomas. Histological grading is related to prognosis; however, it is also subject to interobserver variability. Rare subtypes of chondrosarcoma, including dedifferentiated, mesenchymal, and clear cell chondrosarcoma, are discussed as well. Magnetic resonance imaging is necessary to delineate the extent of the intraosseous and soft tissue involvement preoperatively. Computed tomography is especially recommended in the pelvis and other flat bones where it may be difficult to discern the pattern of bone destruction and the presence of matrix mineralization. Wide, en-bloc excision is the preferred surgical treatment in intermediate- and high-grade chondrosarcoma. In low-grade chondrosarcoma confined to the bone, extensive intralesional curettage followed by local adjuvant treatment and filling the cavity with bone graft has promising long-term clinical results and satisfactory local control. Chondrosarcomas are relatively radiotherapy resistant; therefore, doses >60 Gy are needed in attempts to achieve local control after incomplete resection. Irradiation with protons or other charged particles seems beneficial in this curative situation. Chemotherapy is only possibly effective in mesenchymal chondrosarcoma, and is of uncertain value in dedifferentiated chondrosarcoma. Potential new systemic treatment targets are being discussed.

Establishment of novel human dedifferentiated chondrosarcoma cell line with osteoblastic differentiation

Dedifferentiated chondrosarcoma is a rare, highly malignant variant of chondrosarcoma in which a high-grade sarcoma coexists with a low-grade chondroid tumor. We herein review a case of dedifferentiated chondrosarcoma with an osteosarcoma omit component that occurred in the distal femur of a 38-year-old man. We established the cell line (NDCS-1) from a pleural effusion of the metastatic lung tumor. The cell line was characterized by a the G-banded karyotype, polymerase chain reaction (PCR) single-strand conformation polymorphism analysis, spectral karyotyping, and reverse transcriptase PCR (RT-PCR). The tumor exhibited complex karyotypes and a high frequency of chromosomal amplication with p53 mutation. This tumor revealed an osteoblastic and chondroblastic character in vitro and in severe combined immunodeficiency mice. The expression and phosphorylation of platelet-derived growth factor receptor-beta, which seemed to play a major role in the malignant phenotype of chondrosarcoma, was confirmed by RT-PCR and Western blotting. To our knowledge, this is the first report of the establishment of a human dedifferentiated chondrosarcoma.

Chondrosarcoma of the spine: a rare case with unusual presentation

Chondrosarcoma is the third most common primary malignancy of bone, affecting primarily the pelvic and shoulder girdles and being extremely rare in the spine. Herein, we present a case of a 65-year-old woman with a rare chondrosarcoma of the spine, who presented with clinical symptoms from the lung metastasis. The neoplasm was grade II and exhibited overexpression of the p53 tumor suppressor protein. The latter has been associated with a high propensity for distant metastases.

Diagnostic Relevance of the Immunohistochemical Detection of Growth Factors in Benign and Malignant Cartilaginous Tumors

The goal of this study was to evaluate the diagnostic relevance of the expression of growth factors in cartilaginous tumors and to investigate on the possible correlation with grade, local recurrence, metastatic potential, and survival. Expression of VEGF, PDGF, FGF1, TFGbeta2, TNFalpha, Ki-67, and p53 was analyzed in 21 cases of benign and malignant cartilaginous tumors using immunohistochemistry. Immunohistochemical staining was performed on sections from paraffin-embedded tissue. The correlation of these markers' expression and grading or clinical outcome was also evaluated. Immunohistochemistry revealed a high correlation between grading and VEGF-positive staining (P=0.001). In addition, a correlation with local recurrence was found in cases with a positive expression of Ki-67 (P=0.035), TGFbeta (P=0.007), PDGF (P=0.007), and p53 (P=0.0455), with a time-related association. These data suggest a progressive modification in the biologic behavior of malignant cartilaginous tumors. VEGF could be used as a marker in the preoperative surgical assessment of chondrosarcoma. New therapeutic strategies could be considered for VEGF-positive cases. Positive expression of TGFbeta and PDGF seems to be a predictor of clinical outcome.

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.

The role of thallium-201 and pentavalent dimercaptosuccinic acid for staging cartilaginous tumours

Introduction

Heterogeneity of cartilage tumours may confound accurate diagnosis and grading resulting in under and over treatment. Improved preoperative assessment of malignancy and grade would be invaluable for developing a rational plan for treatment. We examined correlations between nuclear tracer avidity and malignancy grade in cartilage tumours.

Methods

Between 1996 and 2000, 92 consecutive patients with cartilaginous tumours (50 benign, 42 non-metastatic malignant) underwent nuclear scanning. Thallium-201 (TL-201) and pentavalent dimercaptosuccinic acid (DMSAV) were used as nuclear isotopes. Scanning with these agents was performed on separate days 48 hours apart. Static and SPECT images were obtained at 30 m and 4 h after injection of nuclear tracer. Pathology review was undertaken blinded to the results of the nuclear scans and correlations between histologic results and trace uptake at 4 hours examined.

Results

25 patients with negative DMSAV had benign tumours. 15/17 tumours with positive TL-201 had malignant tumours. 11/13 patients with both positive DMSAV and TL-201 scans had intermediate or high grade tumours and 4 of these developed metastases. We have developed an algorithm for the management of patients with tumours that aims to avoid over treatment of low grade tumours and under treatment of high grade tumours.

Conclusion

Functional nuclear scanning with TL-201 and DMSAV complements other imaging modalities in the management of cartilaginous tumours.

A distinct phenotype characterizes tumors from a putative genetic trait involving chondrosarcoma and breast cancer occurring in the same patient

Recently, we documented an increased risk for the occurrence of breast- and cartilaginous tumors in the same patient, statistically pointing towards a potential genetic trait. This trait is most probably not associated with mutations in the two major hereditary breast cancer genes since no cases of enchondroma or chondrosarcoma were found in Dutch BRCA1 and BRCA2 families. We were able to collect and review the tumor tissue samples from 34 patients with both breast- and cartilaginous tumors and compared histopathological and immunohistochemical features of these tumors with controls. Breast cancer controls were available from literature data generated to compare familial breast cancers with nonselected cases. Clinical markers for chondrosarcoma controls were collected from the Netherlands Committee of Bone Tumors. Immunohistochemical data on chondro-tumor controls were available from our own files. Breast tumors of patients with cartilaginous sarcomas showed a significantly higher mitotic count (P=0.001), contained less lymphocyte infiltrate (P=0.025) and less nuclear pleomorphism. Remarkably, all cartilaginous tumors are of one common histological category originating centrally (P=0.014). Estrogen receptor and p53 expression were significantly higher (P<0.001) in breast cancer associated with chondro-tumors. p21 staining was more often negative in chondro-tumors associated with breast cancer. In seven cases of breast cancer, we found a slight decrease in CHEK2 expression. However, we could not identify the CHEK2 1100delC mutation in these cases nor in cases with normal CHEK2 expression. Hierarchical cluster analysis of all parameters within chondro-tumor-associated breast cancer specimens revealed two different subgroups, the largest one associated with estrogen receptor-positive breast cancer, which may distinguish sporadic cases from those belonging to the potential genetic trait. These distinct phenotypic findings support the existence of a new hitherto unrecognized syndrome, characterized by an increased risk to develop both breast cancer and centrally originating cartilaginous tumors.

Platelet-derived growth factor-alpha receptor expression supports the growth of conventional chondrosarcoma and is associated with adverse outcome

Bone cells are important targets of platelet-derived growth factors (PDGFs) because they stimulate proliferation of osteoblasts and chondrocytes. In this study we wanted to determine the expression of PDGF-AA and PDGF-alpha receptor in conventional chondrosarcomas and to compare the results with those obtained from benign enchondromas and non-neoplastic cartilage tissue. Sixty-seven chondrosarcomas, 20 enchondromas, and 5 specimens of healthy cartilage as well as 7 specimens of hypertrophic callus cartilage were immunohistochemically analyzed for the expression of PDGF-AA and PDGF-alpha receptor, respectively. Additionally, the proliferation activity was examined with the MIB-1 antibody. Clinical follow-up data were available from 53 patients. A significant overexpression of receptor and factor was found in chondrosarcomas as compared with enchondromas (PDGF-AA p = 0.013, PDGF-alpha receptor p <0.001). MIB-1 values were significantly higher in chondrosarcomas (p <0.001). In healthy joint cartilage no staining was detectable, whereas reactive cartilage of callus formation showed high expression levels. PDGF-alpha receptor expression was significantly higher in grade 3 chondrosarcomas compared with grade 2 (p = 0.022) and grade 1 tumors (p = 0.002). Survival analysis documented a significantly shorter overall survival for patients with high PDGF-alpha receptor expression (p = 0.0172, log-rank test). Because PDGF-alpha receptor expression positively correlates with the aggressiveness of chondrosarcoma, it may be considered as a possible target for novel therapeutic strategies.

Chondrosarcoma of bone: analysis of 108 cases and evaluation for predictors of outcome

Chondrosarcoma is the second most common malignant bone tumor and is relatively unresponsive to chemotherapy and radiation regimens. In addition, the clinical course of chondrosarcoma is difficult to predict. The purpose of this study was to review the authors' experience with chondrosarcoma and ascertain any factors related to prognosis and clinical outcome. The medical records of 108 patients followed up for a minimum of 2 years were retrospectively reviewed. There were 31 low-grade and 77 high-grade chondrosarcomas. One hundred one patients underwent surgical resection. There was a statistically significant association between positive margins and local recurrence, metastasis, and death. Tumor grade was not predictive of outcome. Proliferation indices (MIB-1 expression determination through immunohistochemistry) were quantitated in 39 patients. A significant association was seen between MIB-1 expression and recurrence and death. Thus, objective quantitation of tumor proliferation was more predictive than was histologic grade of outcome in chondrosarcoma. Although histologic grade continues to be the standard grading system for chondrosarcoma, the current study contributes to ongoing research and validation of alternative techniques that may be more reliable in guiding prognosis and treatment of chondrosarcoma.

Condylar hyperplasia associated to synovial chondromatosis of the temporomandibular joint: a case report

Condylar hyperplasia is a slowly developing malformation of the mandible, with elongation of the mandibular neck, that generally results in facial asymmetry. Synovial chondromatosis is a benign chronic disorder characterized by the formation of multiple small nodules of hyaline cartilage as a result of metaplasia of the synovial connective tissue. It affects mostly the large joints, particularly the knee, hip, elbow and ankle. The temporomandibular joint (TMJ) is rarely affected. The case of a 42-year-old male with a history of left preauricular pain and swelling and deviation of the mandible to the left upon opening the mouth is presented. Computed tomography disclosed hyperplasia of the left condyle with loose radiopaque bodies within the joint cavity. The left TMJ was subject to open surgery, which included resection of four loose bodies and a remodeling condylectomy. The histopathological study confirmed the diagnosis of condylar hyperplasia and chondromatosis of the left TMJ.

Synovial neoformations and tumours

An important group of soft tissue tumours and tumour-like lesions originates from the synovium of the joints, bursae and tendon sheaths. These include synovial chondromatosis, diffuse articular lipomatosis (lipoma arborescens), villonodular synovitis, synovial haemangioma, synovial chondroma and fibroma (intracapsular and peri-articular), primary chondrosarcoma originating from the synovium and synovial sarcoma. The main clinical symptoms of these tumours, such as pain, swelling, effusion and joint locking, are not specific, so the diagnosis can easily be missed in clinical practice. The most important clinical characteristics and the differential diagnostic clues for synovial tumours and tumour-like lesions are described in this chapter. In addition, the new results of genetic and histological studies are discussed, together with a summary of the available evidence-base for therapy.

Synovial chondromatosis: the possible role of FGF 9 and FGF receptor 3 in its pathology

Primary synovial chondromatosis (PSC) is a rare disorder of the synovium typified by cartilaginous nodule formation within the synovial membrane. Fibroblast growth factor receptor 3 (FGFR3) is a recently described specific marker of mesenchymal precartilaginous stem cells. Expression patterns of FGFR3 and its specific ligand, fibroblast growth factor 9 (FGF 9), were evaluated both in situ and in cell cultures. Histologically, cells at the periphery of the cartilage nodules express FGFR3 and PCNA (proliferating cell nuclear antigen). Elevated levels of FGF 9, its specific ligand, have been found in synovial fluids of patients with synovial chondromatosis. Synoviocytes but not chondrocytes from affected patients express FGF9 in culture. This pattern is absent in normal synovium and cartilage. Downregulation of FGF9 may provide a possible nonoperative therapy for PSC.

Changes of the p16 gene but not the p53 gene in human chondrosarcoma tissues

The role of two important tumour suppressor genes, p16 and p53, was evaluated in cartilaginous tumour tissues. Genomic DNA from 22 chondrosarcomas, 5 benign chondroid tumours, 1 sample of reactive proliferative cartilage and 2 samples of normal cartilage were analysed using polymerase chain reaction, single strand conformational polymorphism, DNA sequencing and methylation-specific polymerase chain reaction. The p16 gene was found to be partly methylated in 5 high-grade chondrosarcomas and homozygously deleted in 1 chondrosarcoma. Moreover, a polymorphism was detected in 3 malignant tumours, but not in benign tumours or normal cartilage. Analysis of the p53 gene revealed an unchanged structure in all samples. These findings show a role for p16, but not p53, in chondrosarcoma.

Molecular genetic characterization of both components of a dedifferentiated chondrosarcoma, with implications for its histogenesis

Dedifferentiated chondrosarcoma is defined as a high-grade, anaplastic sarcoma adjacent to a low-grade malignant cartilage-forming tumour. Controversy remains as to whether the anaplastic and cartilaginous components are derived from a common precursor cell, or whether they represent separate genotypic lineages (collision tumour). Both components of a case of dedifferentiated chondrosarcoma were therefore separately investigated by loss of heterozygosity (LOH) analysis, comparative genomic hybridization (CGH), DNA flow cytometry, and p53 analysis. Both showed p53 overexpression and an identical somatic 6 bp deletion in exon 7 of p53. Combination of the CGH and LOH results revealed that both components had lost the same copy of chromosome 13. These results provide compelling evidence in this case for a common origin, instead of the 'collision tumour' theory. Certain genotypic alterations were not shared. The anaplastic component showed severe aneuploidy, LOH at additional loci, and amplification and deletion of several chromosome parts. In contrast, the cartilaginous component had lost chromosomes 5, 22, 17p and part of 16p and revealed an amplification of 17q. The LOH and CGH results further demonstrated that the two components had lost a different copy of chromosome 4. Thus, a substantial number of genetic alterations have occurred after the diversion of the two components, indicating that the separation of the two clones, derived from a single precursor, was a relatively early event in the histogenesis of this case of dedifferentiated chondrosarcoma.

Chondrosarcoma of the phalanx: a locally aggressive lesion with minimal metastatic potential: a report of 35 cases and a review of the literature

BACKGROUND

Enchondroma is the most common primary benign bone tumor of the hand, especially the phalanges, whereas chondrosarcoma is uncommon at this site. Although phalangeal chondrosarcoma may have ominous histologic features, its biologic behavior is relatively indolent.

METHODS

Thirty-five cases of phalangeal lesions previously diagnosed as chondrosarcoma were studied. Histologic and tumor-biologic parameters (Ki-67 and p53 immunohistochemistry) were investigated and correlated with clinical behavior.

RESULTS

All cases were characterized by unequivocal malignant histologic features (Grade 2 or higher) or Grade 1 malignant histologic features combined with the presence of cortical destruction and soft tissue extension. The median age of the patients at the time of diagnosis was 67 years (range 21-87 years), with a slight female predominance. Occurrence in the hand was more common than in the foot, with the proximal phalanx affected most often. Treatment varied from local therapy (curettage or local excision) in 16 patients to amputation or exarticulation in 19 cases. Follow-up ranged from 8-432 months for 28 patients. Ten of 15 tumors treated by local therapy recurred whereas none of 13 tumors treated by radical surgery recurred. The median survival was 20.8 years; none of 28 patients developed metastases nor died of disease. Both the type of treatment and localization in the proximal phalanx were associated independently with local recurrence.

CONCLUSIONS

Phalangeal chondrosarcoma behaves as a locally aggressive lesion and, in contrast to chondrosarcomas located elsewhere, rarely metastasizes. Treatment is indicated only because of its locally destructive growth. The authors believe that given the excellent survival data, curettage with adequate follow-up should be considered as the treatment of choice if technically feasible, especially in those cases in which amputation would lead to a significant loss of hand function.

Collagenase specificity in chondrosarcoma metastasis

The treatment of some mesenchymal malignancies has made significant gains over the past few decades with the development of effective systemic therapies. In contrast, the treatment of chondrosarcoma has been limited to surgical resection, with the most significant prognostic indicators being surgical margins and histologic grade. We have reported that MMP-1/TIMP-1 gene expression serves to prognosticate for tumor recurrence in this group of patients. This led to the hypothesis that collagenase activity facilitates cell egression from the cartilaginous matrix. In the current study we examine the specificity of collagenase gene expression in archival human chondrosarcoma samples using semi-quantitative PCR. Messenger RNA was affinity extracted and subject to reverse transcription. The subsequent cDNA was amplified using novel primers and quantitated by densitometry. Ratios of gene expression were constructed and compared to disease-free survival. The data demonstrate that the significance of the MMP-1/TIMP-1 ratio as a predictor of recurrence is confirmed with a larger number of patients. Neutrophil collagenase or MMP-8 was observed in only 5 of 29 samples. Collagenase-3 or MMP-13 was observed in all samples but the level did not correlate with disease-free survival. Since the collagenases have similar activity for fibrillar collagens and cleave the peptide in the same location, post-transcriptional regulatory mechanisms may account for the observed specificity. The determination of the MMP-1/TIMP-1 gene expression ratio not only serves to identify those patients at risk for recurrence but may also serve as a novel therapeutic avenue as an adjunct to surgical resection.

Chondrosarcoma of bone: an assessment of outcome

BACKGROUND

The data on 227 patients who had been managed for a chondrosarcoma at one institution were reviewed to determine the nature of the lesions, the predictors of outcome, and whether there were any ways to change the treatment approaches to improve the results.

METHODS

The patients were followed for a mean duration of six years (range, three to twenty-five years). The mean age of the patients was forty-seven years (range, nine to eighty-four years). The most prevalent sites of the tumors were the femur (seventy-eight), the pelvis (fifty-one), and the humerus (thirty-nine). The tumors were divided into two groups according to histological grade. Eighty-six tumors (sixteen atypical enchondromas and seventy grade-1 chondrosarcomas) that were locally destructive but were associated with a low likelihood of metastasis were considered to be low-grade. The remaining 141 lesions, which were locally destructive, potentially metastatic, and capable of causing death, were thought to be high-grade. One hundred and three of these 141 lesions were grade 2, and thirty-eight were grade 3 (eighteen of the thirty-eight were grade 3 only, and twenty were both grade 3 and dedifferentiated). Two hundred and twenty-four patients were managed with resection and a limb-sparing procedure; the remaining three patients had an amputation. Postoperative adjuvant radiation was used for fifty-six patients; chemotherapy, for thirty-five; and both radiation and chemotherapy, for nineteen. Flow cytometric patterns were analyzed for 105 patients.

RESULTS

The patients who had a high-grade tumor were older than those who had a low-grade tumor (mean age [and standard deviation], 50+/-17.0 years compared with 40+/-15.9 years; p < 0.001). Pathological fracture, metastasis, local recurrence, and death were more prevalent in the group that had a high-grade lesion (p < 0.001). Predictors of metastasis and death in that group of patients included local recurrence, a pelvic location of the tumor, a tumor that was more than 100 cubic centimeters in size, a ploidic abnormality (aneuploidy coupled with a high mean DNA index), a histological grade of 3, and a dedifferentiated type of tumor (p < 0.001).

CONCLUSIONS

Although the data are suggestive, with the numbers available for study we could not detect a significant difference in the rates of pulmonary metastasis and death between the patients who had a grade-3 lesion and those who had a grade-3 lesion that was also dedifferentiated. However, the interval between diagnosis and death was 32+/-22.8 months for the patients who had a grade-3 lesion compared with 5+/-3.7 months for those who had a grade-3 lesion that was also dedifferentiated (p < 0.001). Overall, patients who had had a resection with wide margins (margins extending outside the reactive zone) had a longer duration of survival than did those who had had a so-called marginal resection (margins extending outside the tumor but within the reactive zone) or an intralesional resection (margins within the lesion) (p < 0.04). Adjunctive chemotherapy or radiation, or both (which, it must be noted, was used, without a protocol, in a relatively small number of patients), after an intralesional resection, for recurrent disease, or for distant metastasis did not appear to alter the outcome.

Growth potential of loose bodies: an immunohistochemical examination of primary and secondary synovial osteochondromatosis

Histologic and immunohistochemical studies of growth potential were performed on 53 surgically removed loose bodies representing 10 cases of primary synovial osteochondromatosis, 37 bodies representing 12 cases of secondary synovial osteochondromatosis, and five bodies representing five cases of osteochondral fracture. Loose bodies in primary synovial osteochondromatosis were nodular, showing plump chondrocytes and irregular calcification, and all contained proliferative cell nuclear antigen-positive chondrocytes (labeling index: 42.5%; range: 36.0-52.0%). Other markers stained less frequently. Loose bodies in secondary synovial osteochondromatosis showed uniform chondrocytes and annular calcification surrounding core tissue. Eighteen of 37 loose bodies showed proliferative cell nuclear antigen-positive chondrocytes, mostly peripherally. Chondrocyte labeling indices were less than 5% for proliferative cell nuclear antigen and other markers, although some connective tissue cells in the outer layer were stained. Loose bodies from osteochondral fractures were composed of articular cartilage, subchondral bone, and connective tissue; cartilage was negative for markers, whereas connective tissue contained positive cells. One specimen showed cartilaginous metaplasia of connective tissue. These results suggest that loose bodies have the potential for slow growth by proliferation of chondrocytes in primary synovial osteochondromatosis and by metaplasia following proliferation of surrounding connective tissue in secondary synovial osteochondromatosis.

Altered p53 is associated with aggressive behavior of chondrosarcoma: a long term follow-up study

BACKGROUND

p53 is a major tumor suppressor gene that has been implicated in the biology of a variety of human neoplasms, including some that affect the skeleton. Recent studies based on small numbers of cases have shown that overexpression or alteration of the p53 gene is frequently present in high grade, clinically aggressive chondrosarcomas of bone. In this study, the authors addressed the relation between overexpression and alteration of the p53 gene and the clinical aggressiveness of chondrosarcoma in a large series of patients for whom long term follow-up data were available.

METHODS

The authors analyzed the expression and/or alteration of the p53 gene in 158 cases of chondrosarcoma of bone using immunohistochemistry, single-strand conformation polymorphism, and direct sequencing. They then related the findings to various clinicopathologic parameters and long term follow-up data.

RESULTS

The presence of overexpression and/or structural alterations of the p53 gene was documented in 38.1% of chondrosarcomas of bone. A statistically significant correlation was observed between overexpression or alteration of the p53 gene and both the histologic grade of the tumor and the presence of metastasis. The probability of local recurrence free, metastasis free, and overall survival was significantly higher for patients with no overexpression or alteration of p53 than for patients with p53 overexpression or alteration.

CONCLUSIONS

Overexpression or alteration of the p53 gene is an important predictor of aggressive clinical behavior in chondrosarcoma of bone.

p53 gene mutations in osteosarcomas of low-grade malignancy

Alterations in tumor suppressor gene p53, localized on chromosome 17p13, are considered to play a significant role in the initiation and, to some extent, even in the progression of various malignant tumors. In this respect, investigations on conventional highly malignant osteosarcomas have shown a mutation rate of approximately 20%. However, currently, data on the mutation rate in the group of variant histology osteosarcomas of low-grade malignancy do not exist. Therefore, we investigated a panel of low malignant entities (five low malignant intramedullary osteosarcomas grade 1; one intramedullary osteosarcoma grade 2; eight parosteal osteosarcomas, including one local recurrence grades 1 and 2, and five periosteal osteosarcomas grade 2) with polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis focusing on exons 4 to 8 of the p53 gene followed by direct sequencing. Point mutations were found in one low-grade osteoblastoma-like osteosarcoma and in two periosteal osteosarcomas grade 2 (one missense, one silent, and one nonsense mutation). This mutation rate of 15.7% (3 of 19) is comparable to that determined in highly malignant osteosarcomas. Moreover, the analysis of clinical data did not show any difference in the behavior of tumors with p53 mutations compared with those without. Therefore, we suggest that alterations in p53 gene are an early event in the tumorigenesis of malignant osteoblastic tumors without impact on progression of these tumors.

Mutations of the adenomatous polyposis coli and p53 genes in a child with Turcot's syndrome

Turcot's syndrome is a rare heritable complex that is characterized by an association between a primary neuroepithelial tumor of the central nervous system and multiple colonic polyps. The aim of this study was to analyze genetic alterations in a case of Turcot's syndrome in a 10.5-year-old boy in whom a colorectal tumor developed 3.5 years following astrocytoma. An APC germline non-sense mutation at codon 1284 leading to a truncated protein was identified, as was a somatic p53 mutation in the colorectal carcinoma in exon 7, codon 244. The latter was not identified in the primary astrocytoma. However, immunohistochemistry revealed high p53 protein expression in both tumors, suggesting an additional p53 mutation in the primary astrocytic tumor. The diverse p53 mutations observed in this unique syndrome in two different sites and stages of the disease may shed light on the multistep progression of the malignant events.

p53 mutations in chondrosarcoma

Chondrosarcoma is a primary bone tumor that has several different grades and variants. We evaluated 48 chondrosarcomas for p53 overexpression and p53 mutations. p53 expression was evaluated with immunohistochemistry using monoclonal antibodies PAb421, PAb1801, and PAb240. p53 mutations were identified with single-strand conformational polymorphism (SSCP) and DNA sequencing in selected cases. Immunohistochemistry revealed nuclear staining with PAb421 and PAb1801 in the spindle cell portion of one dedifferentiated chondrosarcoma. SSCP analysis was abnormal only in the case with positive immunostaining and localized the mutation to exons 7 and 8. DNA sequence analysis identified a point mutation of G to C in codon 276, resulting in an amino acid substitution of proline for alanine. This point mutation has been reported previously in other tumors but not in chondrosarcoma. Assimilation of our results with previous studies suggests that p53 mutations are present in a minority of chondrosarcomas but when present, are in higher grade chondrosarcomas and their variants.

Cell proliferation studies in primary synovial chondromatosis

Primary synovial chondromatosis (PSC) is thought to be a cartilaginous metaplasia, but it may recur locally and malignant change has been reported. Histologically, the cartilage is usually cellular, with binucleate forms. These findings suggest that the disease is not simply a metaplasia but imply a proliferative component. In this study, immunohistochemical detection of Ki-67 protein using an antigen retrieval microwave heating technique and DNA image cytometry (VIDAS image analysis system) has been used to assess the proliferative activity in 20 cases of PSC and the results have been compared with those obtained in other cartilage tissues: ten enchondromas, ten chondrosarcomas, and ten samples of normal articular cartilage. There was no detectable staining for Ki-67 protein in cases of PSC or in benign tissues, but there was a significant association between Ki-67 labelling index and grade in the chondrosarcomas (P < 0.01). The absence of mitotic figures and the lack of Ki-67 protein in PSC are consistent with a metaplasia. All enchondromas gave diploid DNA histograms but non-diploid histograms were obtained i eight cases (40 per cent) of PSC, with significant populations of hyperdiploid and DNA aneuploid cells. The mean DNA content, the percentage of hyperdiploid cells, the percentage of DNA aneuploid cells, and the 2c deviation index were all significantly higher in PSC than in enchondromas (P < 0.01). These findings with image cytometry suggest a proliferative process in the development of at least some cases of PSC. In terms of cell proliferative activity, PSC appears to occupy a position which is intermediate between benign enchondromas and malignant chondrosarcomas, which may explain the aggressive clinical behaviour occasionally seen in this condition.

Analysis of p53 expression in osteosarcoma of the jaw: correlation with clinicopathologic and DNA ploidy findings

The objective of this study was to determine whether p53 expression correlated with clinicopathological and DNA ploidy in osteosarcoma of the jaw, a particular subtype of osteosarcoma associated with an older age at presentation, longer median survival, rare metastasis, and death due to uncontrolled local recurrence. Seventeen cases of osteosarcoma of the jaw were stained for p53 using CM1 antibody (Novocastra). Eight cases (47.5%) showed nuclear staining in more than 10% of the neoplastic nuclei. Ploidy analysis showed 13 aneuploid (eight p53+) and three diploid (none p53+) tumors. No significant relationship was found between p53 positivity and clinicomorphological features, DNA ploidy or survival. p53-positive cases were, however, more commonly associated with aneuploidy and chondroblastic differentiation. These results indicate that p53 immunostaining does not seem to provide prognostic information in osteosarcoma of the jaw.

Lesions of the bones of the hands and feet

Neoplasms and their simulators in the bones of the hands and feet include the majority of those found in other skeletal sites, and a disproportionate number of some. We examined the clinical, radiologic, and pathologic features of 240 lesions of the hand and foot bones. Benign tumors and lesions including reactive and reparative conditions comprised 203 cases. The largest single category of neoplasms was that with cartilaginous differentiation, with enchondromas (29 cases) and chondrosarcomas (15 cases) the most common. Noncartilaginous malignant tumors were infrequent and displayed typical radiologic and pathologic features. Florid reactive periostitis, bizarre parosteal osteochondromatous proliferations, and giant cell reparative granulomas made up a larger percentage of lesions in these locations than in other skeletal sites. Lesions of the bones of the hands and feet may frequently be biopsied or treated at hospitals without large orthopedic tumor services. Thus, it is important for the surgical pathologist to be aware of the frequency and characteristics of lesions which may present in these sites.

Dedifferentiated chondrosarcoma of the rib with a malignant mesenchymomatous component: an autopsy case report

A rare variant of dedifferentiated chondrosarcoma with malignant mesenchymomatous component in a 57-year-old male is reported. The patient presented with a posterior mediastinal mass arising from the left eighth and ninth ribs showing well differentiated, low-grade chondrosarcoma. Five years later, local recurrence occurred and an excised specimen also showed the same histological features as the primary tumor. Another 6 years later, the tumor recurred and metastasized to the multiple organs, the patient dying 4 months later. Autopsy revealed that the recurrent and metastatic tumors showed malignant mesenchymomatous 'dedifferentiation' of chondrosarcoma composed of rhabdomyosarcoma, angiosarcoma, chondrosarcoma, osteosarcoma, and leiomyosarcoma, in addition to fibrosarcomatous areas. Although the less differentiated component of dedifferentiated chondrosarcoma usually shows the histological features of malignant fibrous histiocytoma and fibrosarcoma, multilineage differentiation can occur in that component. The phenomenon of 'dedifferentiation' in chondrosarcoma and the relationship to and distinction from malignant mesenchymoma of soft tissue and bone are discussed.