Immunohistochemical analysis for Sox9 reveals the cartilaginous character of chondroblastoma and chondromyxoid fibroma of the bone

Comprehensive Insights into Chondroblastoma Metastasis: Metastatic Patterns and Therapeutic Approaches

Chondroblastoma metastasis, though rare, represents a clinically significant and notably important aspect of bone tumors. Understanding its epidemiological characteristics, pathological features, and treatment modalities, despite its infrequency, is imperative for comprehensive patient management. This review aims to elucidate the epidemiology, molecular mechanisms, diagnostic challenges, and therapeutic strategies associated with chondroblastoma metastasis. The patterns, prognostic factors, and treatment outcomes were explored through an analysis of case studies and clinical reports. Notably, we highlighted emerging therapeutic perspectives aimed at improving patient outcomes. To the best of our knowledge, there has been no previous review addressing these matters cumulatively, highlighting a significant gap in the existing scholarly literature. By shedding light on the nuances of chondroblastoma metastasis, this review contributes to the advancement of knowledge in this field and informs clinical decision-making for improved patient care.

Molecular In-Depth Characterization of Chondrosarcoma for Current and Future Targeted Therapies

Chondrosarcoma (CHS) are heterogenous, but as a whole, represent the second most common primary malignant bone tumor entity. Although knowledge on tumor biology has grown exponentially during the past few decades, surgical resection remains the gold standard for the treatment of these tumors, while radiation and differentiated chemotherapy do not result in sufficient cancer control. An in-depth molecular characterization of CHS reveals significant differences compared to tumors of epithelial origin. Genetically, CHS are heterogenous, but there is no characteristic mutation defining CHS, and yet, IDH1 and IDH2 mutations are frequent. Hypovascularization, extracellular matrix composition of collagen, proteoglycans, and hyaluronan create a mechanical barrier for tumor suppressive immune cells. Comparatively low proliferation rates, MDR-1 expression and an acidic tumor microenvironment further limit therapeutic options in CHS. Future advances in CHS therapy depend on the further characterization of CHS, especially the tumor immune microenvironment, for improved and better targeted therapies.

Chondroblastoma of foot bones; a clinicopathological study of 29 cases confirming the diagnostic utility of H3K36M and H3G34W antibodies at an uncommon site

OBJECTIVE

Chondroblastoma (CB) is a benign cartilaginous bone neoplasm which commonly occurs in long bones of adolescents. CB can uncommonly involve foot. Its mimics include both benign and malignant lesions. H3K36M immunohistochemical (IHC) stain is a helpful tool for establishing the diagnosis of CB in such challenging situations. In addition, H3G34W IHC stain helps to rule out giant cell tumor which is the closest differential of CB. Our objective was to describe the clinicopathological features and frequencies of H3K36M, H3G34W and SATB2 IHC stains in CB of foot.

MATERIALS AND METHODS

We reviewed H&E slides and blocks of 29 cases diagnosed as "chondroblastoma" of foot at our institutions.

RESULTS

Patient's age ranged from 6 to 69 (mean: 23.3 and median: 23) years. Males were almost 5 times more commonly affected than females. Talus and calcaneum were involved in 13 (44.8 %) cases each. Microscopically, tumors were composed of polygonal mononuclear cells and multinucleated giant cells and chondroid matrix. Other histological features included aneurysmal bone cyst-like (ABC-like) change (44.8 %), osteoid matrix (31 %), chicken-wire calcification (20.7 %), and necrosis (10.3 %). H3K36M was expressed in 100 % and SATB2 in 91.7 % cases. H3G34W was negative in all cases, where performed. One out of 11 patients with follow up information developed local recurrence after 48 months.

CONCLUSION

CB in foot occur at an elder age and show more frequent ABC-like changes as compared to long bones. Males are affected ~5:1 as compared to 2:1 in long bones. H3K36M are H3G34W are extremely useful diagnostic markers for CB, especially elderly (aged or higher) patients and we report the largest series of foot CB cases confirmed by immunohistochemistry.

Expression of SATB2, RUNX2, and SOX9 and possible osteoblastic and chondroblastic differentiation in chondroblastoma

Chondroblastoma (CB) is histologically characterized by oval to polygonal-shaped mononuclear neoplastic cells, multinucleated osteoclastic giant cells, and eosinophilic matrix with occasional calcification. Genetically, the majority of CBs harbor H3F3B p.K36M mutation. Despite the historical nomenclature, it has been reported that the matrix of CB is similar to osteoid rather than true cartilage; however, it remains unclear whether neoplastic cells in CB have the potential for osteoblastic differentiation. To clarify this issue, we immunohistochemically examined the expression of osteogenic and chondrogenic markers (SATB2, RUNX2, p63, and SOX9) as well as H3K36M mutant protein in 33 cases of CB. All 33 cases of CB were positive for H3K36M, while SATB2, RUNX2, p63, and SOX9 were expressed in 30/33 (91%), 33/33 (100%), 29/33 (88%), and 31/32 (97%) CB cases, respectively. Our immunohistochemical results suggest that neoplastic cells in CB frequently express both osteogenic and chondrogenic markers and may have an intermediate feature of osteoblastic and chondroblastic nature.

GRM1 Immunohistochemistry Distinguishes Chondromyxoid Fibroma From its Histologic Mimics

Chondromyxoid fibroma (CMF) is a rare benign bone neoplasm that manifests histologically as a lobular proliferation of stellate to spindle-shaped cells in a myxoid background, exhibiting morphologic overlap with other cartilaginous and myxoid tumors of bone. CMF is characterized by recurrent genetic rearrangements that place the glutamate receptor gene GRM1 under the regulatory control of a constitutively active promoter, leading to increased gene expression. Here, we explore the diagnostic utility of GRM1 immunohistochemistry as a surrogate marker for GRM1 rearrangement using a commercially available monoclonal antibody in a study of 230 tumors, including 30 CMF cases represented by 35 specimens. GRM1 was positive by immunohistochemistry in 97% of CMF specimens (34/35), exhibiting moderate to strong staining in more than 50% of neoplastic cells; staining was diffuse (>95% of cells) in 25 specimens (71%). Among the 9 CMF specimens with documented exposure to acid decalcification, 4 (44%) exhibited diffuse immunoreactivity (>95%) for GRM1, whereas all 15 CMF specimens (100%) with lack of exposure to decalcification reagents were diffusely immunoreactive ( P =0.003). High GRM1 expression at the RNA level was previously observed by quantitative reverse transcription polymerase chain reaction in 9 CMF cases that were also positive by immunohistochemistry; low GRM1 expression was observed by quantitative reverse transcription polymerase chain reaction in the single case of CMF that was negative by immunohistochemistry. GRM1 immunohistochemistry was negative (<5%) in histologic mimics of CMF, including conventional chondrosarcoma, enchondroma, chondroblastoma, clear cell chondrosarcoma, giant cell tumor of the bone, fibrous dysplasia, chondroblastic osteosarcoma, myoepithelial tumor, primary aneurysmal bone cyst, brown tumor, phosphaturic mesenchymal tumor, CMF-like osteosarcoma, and extraskeletal myxoid chondrosarcoma. These results indicate that GRM1 immunohistochemistry may have utility in distinguishing CMF from its histologic mimics.

Special AT-rich sequence-binding protein 2 (SATB2) in the differential diagnosis of osteogenic and non-osteogenic bone and soft tissue tumors

Background

The diagnosis of osteosarcoma (OSA) depends on clinicopathological and radiological correlation. A biopsy is considered the gold standard for OSA diagnosis. However, since OSA is a great histological mimicker, diagnostic challenges exist. Immunohistochemistry (IHC) can serve as an adjunct for the histological diagnosis of OSA. Special AT-rich sequence-binding protein 2 (SATB2) was recently described as a reliable adjunct immunohistochemical marker for the diagnosis of OSA.

Methods

We investigated the IHC expression of SATB2 in 95 OSA and 100 non-osteogenic bone and soft tissue tumors using a monoclonal antibody (clone EPNCIR30A). The diagnostic utility of SATB2 and correlation with clinicopathological parameters were analyzed.

Results

SATB2 IHC was positive in 88 out of 95 cases (92.6%) of OSA and 50 out of 100 cases (50.0%) of primary non-osteogenic bone and soft tissue tumors. Of the 59 bone tumors, 37 cases (62.7%) were positive for SATB2, and of the 41 soft tissue tumors, 13 cases (31.7%) were positive for SATB2. The sensitivity of SATB2 as a diagnostic test was 92.6%, specificity 50%, positive predictive value 63.8%, and negative predictive value 87.7%.

Conclusions

Although SATB2 is a useful diagnostic marker for OSA, other clinical, histological and immunohistochemical features should be considered for the interpretation of SATB2.

Anti-histone H3.3K36M Antibody is a Highly Sensitive and Specific Immunohistochemistry Marker for the Diagnosis of Chondroblastoma. A Validation Based on Study 136 Cases Comprising Chondroblastoma and its Mimics from Single a Centre in India

Introduction: Chondroblastoma has a wide range of differential diagnosis encompassing various benign and malignant entities. The closest differential diagnosis is giant cell tumor of the bone due to overlapping radiological and histomorphological features. Extensive aneurysmal bone cyst like changes and lack of adequately sampled chondroid matrix often masquerades the primary bone lesion and amplifies the diagnostic difficulty in small biopsies with limited tissue. Immunohistochemistry is helpful in such instances to resolve the diagnostic dilemma. Objectives: To analyze the immunohistochemical expression of anti-histone H3F3K36M antibody inchondroblastoma and validate its utility in differentiating chondroblastomafrom its histological mimics. Material and methods: Immunohistochemistry was performed using anti-histone antibody H3.3K36M in 44 histologically diagnosed chondroblastoma and 92 other histological mimickers. All chondroblastoma and giant cell tumor of the bone included in the study were also tested for anti-histone H3.3 G34W antibody. Of the 33 giant cell tumors of bone with classic morphology and imaging findings, 24 H3.3 G34W positive and 9 negative tumors were included intentionally to rule out the possibility of chondroblastoma. The sensitivity, specificity, positive and negative predictive value of marker with regard to chondroblastoma was calculated. Results: Immunohistochemistry revealed unequivocal nuclear positivity for H3.3K36M in the mononuclear cells in all the 44 Chondroblastoma tested, denoting a sensitivity of 100% cases. Allthesetumors tested simultaneously for anti-histone H3.3G34W were negative. None of the histological mimickers were positive H3.3K36M indicating a specificity of 100%. The positive and negative predictive value was 100%. Conclusion: H3.3K36M mutant antibody is highly sensitive and specific IHC marker and can be used as a valuable adjunct to distinguish chondroblastomafrom its histological mimics especially on small biopsies.

Benign Bone Tumors: An Overview of What We Know Today

Nonmalignant bone tumors represent a wide variety of different entities but maintain many common features. They usually affect young patients, and most can be diagnosed through imaging exams. Often asymptomatic, they can be discovered incidentally. Due to their similarities, these tumors may be challenging to diagnose and differentiate between each other, thus the need for a complete and clear description of their main characteristics. The aim of this review is to give a picture of the benign bone tumors that clinicians can encounter more frequently in their everyday work.

Chondrosarcoma-from Molecular Pathology to Novel Therapies

Chondrosarcoma (CHS) is the second most common primary malignant bone sarcoma. Overall survival and prognosis of this tumor are various and often extreme, depending on histological grade and tumor subtype. CHS treatment is difficult, and surgery remains still the gold standard due to the resistance of this tumor to other therapeutic options. Considering the role of differentiation of CHS subtypes and the need to develop new treatment strategies, in this review, we introduced a multidisciplinary characterization of CHS from its pathology to therapies. We described the morphology of each subtype with the role of immunohistochemical markers in diagnostics of CHS. We also summarized the most frequently mutated genes and genome regions with altered pathways involved in the pathology of this tumor. Subsequently, we discussed imaging methods and the role of currently used therapies, including surgery and the limitations of chemo and radiotherapy. Finally, in this review, we presented novel targeted therapies, including those at ongoing clinical trials, which can be a potential future target in designing new therapeutics for patients with CHS.

Total Calcanectomy and Bilateral Iliac Bone Autograft Reconstruction for the Treatment of Calcaneal Chondroblastoma Involving a Secondary Aneurysmal Bone Cyst: A Case Report and Literature Review

Chondroblastoma is a rare, benign, cartilaginous-derived tumor accounting for ∼1% to 2% of all primary bone tumors and almost 9% of all benign bone tumors. In this case report, we describe a patient with chondroblastoma and a secondary aneurysmal bone cyst, with the adjacent talus being mildly affected. The initial diagnosis was giant cell tumor and was then confirmed after computed tomography-assisted biopsy. We performed a total calcanectomy via bilateral structural iliac bone autografting to relieve pain and reconstruct the loadbearing function because of the presence of extensive lesions. The patient was pain free and expressed satisfaction with postsurgical dorsiflexion and plantarflexion function at the 60-month follow-up visit. Radiographic images showed that the autografted iliac bone was completely healed, with no evidence of local recurrence.

Chondromyxoid Fibroma of the Temporal Bone: Case Report and Literature Review

Chondromyxoid fibroma (CMF) is a rare, benign, cartilaginous bone tumor that commonly affects the metaphysis of the lower-extremity long bones in young adults. Involvement of the craniofacial bones, especially the temporal bone, is exceedingly rare. We report a case of a 64-year-old man who presented with a left ear mass, but on subsequent imaging was found to have a more extensive mass centered in the temporal bone. Initial biopsy raised the concern for a low-grade chondrosarcoma. However, following surgical resection, a diagnosis of CMF was rendered. The clinical findings, radiographic features, histology, and differential diagnoses are discussed.

Differential Diagnosis of Cartilaginous Lesions of Bone

CONTEXT.—

Cartilaginous tumors represent one of the most common tumors of bone. Management of these tumors includes observation, curettage, and surgical excision or resection, depending on their locations and whether they are benign or malignant. They can be diagnostically challenging, particularly in small biopsies. In rare cases, benign tumors may undergo malignant transformation.

OBJECTIVE.—

To review common cartilaginous tumors, including in patients with multiple hereditary exostosis, Ollier disease, and Maffucci syndrome, and to discuss problems in the interpretation of well-differentiated cartilaginous neoplasms of bone. Additionally, the concept of atypical cartilaginous tumor/chondrosarcoma grade 1 will be discussed and its use clarified.

DATA SOURCES.—

PubMed (US National Library of Medicine, Bethesda, Maryland) literature review, case review of archival cases at the Massachusetts General Hospital, and personal experience of the authors.

CONCLUSIONS.—

This review has examined primary well-differentiated cartilaginous lesions of bone, including their differential diagnosis and approach to management. Because of the frequent overlap in histologic features, particularly between low-grade chondrosarcoma and enchondroma, evaluation of well-differentiated cartilaginous lesions should be undertaken in conjunction with thorough review of the imaging studies.

[Giant cell tumor of bone : Morphology, molecular pathogenesis, and differential diagnosis]

The histological picture of giant cell tumor of bone is characterized by numerous osteoclast-like giant cells. However, these are not the actual tumor cells, but constitute a reactive infiltrate. Rather, the tumor cells are mononuclear mesenchymal cells, which even reveal an osteoblastic line of differentiation. The CD68-positive macrophages form the second group of mononuclear cells. The receptor activator of nuclear factor kappa-B/ligand (RANK/RANKL) system, which belongs to the tumor necrosis factor (TNF) cytokine family, is decisively involved in the activation of the giant cells. It is generally accepted that a RANKL expression of mononuclear stromal cells is responsible for the development and differentiation of osteoclast-like giant cells. Therefore, the RANKL inhibitor denosumab constituted an essential element for giant cell tumor therapy over the last several years, as it blocks the maturation of osteoclasts and thus the osteolytic activity and the spread of tumor. However, with time it became evident that the not risk-free therapy with denosumab may lead to extensive recurrences upon withdrawal, so this therapy is applied with caution today.At the molecular genetic level, the giant cell tumors of bone are characterized by point mutations in the H3F3A gene. The detection of this mutation is used for the diagnostic differentiation from other bone lesions containing giant cells. Giant cell osteosarcomas rarely contain H3F3A mutations. Chondroblastoma is characterized by mutations in the H3F3B gene.

Immunohistochemical analysis of 36 cases of chondroblastomas: A single institutional experience

Chondroblastoma is a relatively uncommon, primary benign bone tumor, frequently identified in young individuals. Despite its classical radiologic and histopathological features, at times, it is fraught with a diagnostic challenge, especially differentiating it from a giant cell tumor of bone (GCTB); an osteosarcoma and a chondrosarcoma. Lately, few studies have shown the diagnostic utility of immunohistochemical (IHC) expression DOG1 antibody in chondroblastomas. The present study was undertaken to evaluate IHC expression of S100 protein, DOG1 and p63 in 36 chondroblastomas. From January 2013 to July 2019 (6-year duration), 106 chondroblastomas were diagnosed, with IHC staining performed in 36 cases. Conventional Hematoxylin and Eosin stained microsections and IHC stained sections were reviewed in 36 cases. IHC staining of p63 (intranuclear), S100 protein (nuclear and cytoplasmic) and DOG1 (cytoplasmic membranous) was recorded in various cases. Seventy-four tumors occurred in males and 32 in females, within age-range of 7-55 years (average = 18.6), frequently in tibia (33/106; 31.1%), followed by femur (26, 24.5%) humerus (22, 20.7%), calcaneum (5) and scapula (4). IHC staining for S100P was positive in 33/36cases (91.7%); DOG1 in 16/19 (84.2%) cases and p63 in 10/15cases (66.6%). DOG1 immunostaining was negative in 25 various other tumors. Sensitivity and specificity for S100P, DOG1and p63 in chondroblastomas was (91.6%, 59.3%); (84.2%, 100%) and (66.6%, 46.6%), respectively. P63 was positively expressed in 15/27 (55.5%) GCTBs. S100 protein and DOG1 can be utilized for a confirmatory diagnosis of a chondroblastoma, especially for differentiating it from its other differentials, such as GCTB, in view of certain associated therapeutic implications. P63 is not useful in that scenario.

Histone H3K36M mutation and trimethylation patterns in chondroblastoma

AIMS

Histones are essential components of chromatin, and mutations in histones lead to alterations in methylation and acetylation, which play an important role in tumorigenesis. Most of the chondroblastomas harbour the H3K36M mutation. With the availability of a mutation-specific antibody, we sought to assess the sensitivity of this antibody and the alterations of histone methylation in a series of chondroblastoma cases.

METHODS AND RESULTS

Immunohistochemical staining with antibodies against H3K36M, trimethylated histones (H3K27me3 and H3K36me3) and an osteoblastic marker (SATB2) was performed on 27 chondroblastomas from 27 patients. The clinical and radiological characteristics of each patient were reviewed. All 27 tumours showed typical radiological and histological features of chondroblastoma, with a subset of cases showing secondary aneurysmal bone cyst changes (11/27), giant-cell-rich foci (4/27), and matrix-rich areas mimicking chondromyxoid fibroma (1/27). All except one case (26/27, 96%) showed positive H3K36M immunostaining (nuclear). In the majority of cases, there was a diffuse staining pattern. Immunohistochemical staining for H3K27me3 and H3K36me3 showed a heterogeneous staining pattern in all cases, regardless of mutation status. None of the cases showed loss of positivity or diffuse positivity. Focal or diffuse SATB2 expression was seen in 21 of 26 tumours (81%).

CONCLUSION

Our results demonstrate that the vast majority of chondroblastomas are positive for H3K36M by immunohistochemical analysis, confirming its diagnostic value. H3K27me3 expression and H3K36me3 expression are heterogeneous in these tumours.

Updates in Primary Bone Tumors: Current Challenges and New Opportunities in Cytopathology

The review summarizes the current diagnostic challenges in fine-needle aspiration of primary bone tumors, with focus on the application of new molecular and immunohistochemical techniques in the diagnosis of giant cell-rich neoplasms, chondrosarcomas, and notochordal tumors.

Selected Giant Cell Rich Lesions of the Temporal Bone

Giant cell rich lesions of the temporal bone encompass a wide spectrum of disease that includes infectious, reactive, and neoplastic processes. When dealing with any lesion that can potentially involve bone, it is important to understand both the clinical presentation and to correlate the histologic findings with the radiologic imaging. This review discusses the clinical, the pathologic features including the differential diagnosis, and the treatment of some of the more commonly encountered giant cell rich entities in this region.

Chondroblastoma: An Update

Chondroblastoma is a rare primary bone tumor of young people that typically arises in the ends of the long bones. Radiologic investigations show a small, circumscribed, lytic lesion. The tumor is characterized histologically by the proliferation of chondroblasts along with areas of mature cartilage, giant cells, and occasionally, secondary aneurysmal bone cyst formation. Chondroblastoma, however, may also present with atypical features, such as prominent hemosiderin deposition, numerous giant cells, or the presence of a large aneurysmal bone cyst component. Malignant entities such as clear cell chondrosarcoma and chondroblastic osteosarcoma must also be considered. Recently, immunohistochemical stains such as DOG1 and SOX9 have been described in chondroblastoma, and K36M mutations in either the H3F3A or H3F3B genes have also been identified. While generally regarded as a benign entity, chondroblastoma manifests an intermediate type of behavior, given its ability to recur locally, and rarely, metastasize.

A diagnosis of giant cell-rich tumour of bone is supported by p63 immunohistochemistry, when more than 50 % of cells is stained

Some primary malignant or benign tumours of bone contain numerous multinucleated cells. These "giant cell-rich tumours of bone" have overlapping features and clinical and radiological data are needed to reach an accurate pathological diagnosis. We studied the potential contribution of p63 immunohistochemistry to the reliability of the histological diagnosis. We performed a multicentric retrospective study of 291 giant cell-rich tumours of bone which included 119 giant cell tumours of bone (GCTB), 76 aneurysmal bone cysts (ABC), 49 chondroblastomas (CB), 15 nonossifying fibromas (NOF), 10 giant cell reparative granulomas (RG) of jaws, 1 giant cell lesion of small bones, 2 hyperparathyroidism-related brown tumours (BT), 17 bone sarcomas with numerous osteoclasts and 2 malignant giant cell tumours of bone. p63 is expressed in ABC, CB, NOF, RG, BT and GCTB, but its expression in more than 50 % of mononuclear cells is strongly suggestive of a diagnosis of GCTB. In contrast, malignant GCTB were mostly negative. Our results show that p63 is expressed in a broad range of benign giant cell-rich tumours of bone, consistent with data in the recent literature, while infrequent in malignant tumours. With a cut-off 50 %, the presence of p63 positive cells is useful in supporting a diagnosis of giant cell-rich tumour of bone. However, a final diagnosis cannot be made without due consideration of all clinical/radiological and pathological data.

Intermittent administration of human parathyroid hormone before osteosynthesis stimulates cancellous bone union in ovariectomized rats

It has been reported that intermittent administration of human parathyroid hormone (h-PTH) promotes bone healing after surgery for osteoporotic fractures. If bone healing is promoted by the administration of h-PTH during pre-operative waiting period, we can prevent prolonged bed rest. Therefore, we evaluated the effects of pre-operative h-PTH treatment on cancellous bone union and its mechanism for fracture healing in ovariectomized rats as a model for osteoporosis. Ovariectomized 7-month-old female Sprague-Dawley rats underwent an osteotomy of the proximal tibia as a fracture model, and h-PTH (30 μg/kg body weight) or vehicle was administered as a pre-operative treatment for one week. After the one-week treatment, tibiae were fixed with wire for osteosynthesis, and h-PTH or vehicle was administered for 1 or 3 weeks following wire fixation. In addition to bone histomorphometry, we used alcian blue/hematoxylin stained sections for evaluating cartilage volume and immunostained sections for analyzing the expression of proliferating cell nuclear antigen (PCNA) for cell proliferation and that of Sox9 and Runx2, differentiation markers for cartilage cells and osteoblasts, respectively. Pre-operative treatment with PTH significantly increased bone volume. Pre-operative and pre- to post-operative treatment with PTH for 2 weeks significantly promoted bone union. Pre-operative treatment with PTH significantly increased cartilage volume, and pre- to post-operative treatment with PTH for 2 weeks significantly increased the percentage of cells positive for Runx2 (p < 0.01), but not PCNA or Sox9. Pre-operative administration of h-PTH enhances bone union by promoting cartilage formation and cell differentiation to osteoblasts, but not by promoting cell proliferation.

Chondroblastoma and chondromyxoid fibroma

Chondroblastoma and chondromyxoid fibroma are benign but locally aggressive bone tumors. Chondroblastoma, a destructive lesion with a thin radiodense border, is usually seen in the epiphysis of long bones. Chondromyxoid fibroma presents as a bigger, lucent, loculated lesion with a sharp sclerotic margin in the metaphysis of long bones. Although uncommon, these tumors can be challenging to manage. They share similarities in pathology that could be related to their histogenic similarity. Very rarely, chondroblastoma may lead to lung metastases; however, the mechanism is not well understood.

SOX9 gene plus heparinized TGF-β 3 coated dexamethasone loaded PLGA microspheres for inducement of chondrogenesis of hMSCs

Microparticulated types of scaffolds have been widely applied in stem cell therapy and the tissue engineering field for the regeneration of wound tissues. During application of simple genes or growth factors and cell delivery vehicles, we designed a method that employs dexamethsone loaded PLGA microspheres consisting of polyplexed SOX9 genes plus heparinized TGF-β 3 on the surface of polymeric microspheres prepared using a layer-by-layer (LbL) method. The fabrication of the polyplexed SOX9 genes plus heparinized TGF-β 3 and their subsequent coating onto dexamethsone loaded PLGA microspheres represents a method for functionalization of the polymeric matrix. The use of SOX9 gene plus heparinized TGF-β 3 coated dexamethsone loaded PLGA microspheres was evaluated to determine their potential as both gene carriers and cell delivery vehicle. By adhesion of hMSCs onto SOX9 gene plus heparinized TGF-β 3 coated dexamethsone loaded PLGA microspheres, the chondrogenesis-related specific genes of collagen type II were increased 30 times comparing to control. Also, the specific extracellular matrix of glycosaminoglycan (GAG) production of hMSCs adhered onto SOX9 gene plus heparinized TGF-β 3 coated dexamethasone loaded PLGA microspheres increased more 2.5 times than control group. Not only in vitro culture but in vivo results, the specific genes of COMP, aggrecan, collagen type II, and SOX9 showed much more gene expressions such as 20, 15, 10, 8 times.

Fine needle aspiration cytology in two cases of chondromyxoid fibroma of bone and review of literature

We report the cytological features of two cases of chondromyxoid fibroma (CMF) confirmed by histopathology examination. First case was a 40-year-old male who presented with a foot swelling, and the second case was a 16-year-old male with a lesion at the angle of jaw. A fine needle aspiration cytology (FNAC) was performed in both the cases. In first case, a correct diagnosis of CMF could be offered on FNAC. In the second case, though the cytology diagnosis was a sarcoma considering the cytological, radiological and clinical features, the histopathological examination confirmed the same to be a CMF. The cases are being discussed to highlight the usefulness of FNAC to diagnose these uncommon benign bone lesions and the potential pitfalls in the cytological diagnosis of chondroid lesions.

Discovered on gastrointestinal stromal tumour 1 (DOG1): a useful immunohistochemical marker for diagnosing chondroblastoma

AIMS

  Cellular areas of chondroblastoma are composed of polygonal chondroblasts with indented nuclei and scattered osteoclast-type multinucleated cells. To learn more about the phenotype of chondroblasts, we investigated the expression of several established immunohistochemical markers in chondroblastomas.

METHODS AND RESULTS

  Nine chondroblastomas were analysed using immunohistochemical antibodies [CD34, α-smooth muscle actin (α-SMA), DOG1, CD117, AE1/AE3 and CD163]. Ten chondromyxoid fibromas, seven giant cell tumours of bone and four foetal proximal femurs were also analysed. The cellular areas of each chondroblastoma contained nests of DOG1(+) αSMA(+) CD117(-) CD34(-) chondroblasts, a phenotype that was not detected in chondromyxoid fibroma cases or in giant cell tumours. Although AE1/AE3 was expressed in all chondroblastomas, the staining intensity and proportion of the positive cells varied widely. Intra-lesional CD163(+) macrophages were detected in all cases of chondroblastoma, chondromyxoid fibroma and giant cell tumours.

CONCLUSIONS

  Our results demonstrated nests of membranous DOG1(+) chondroblasts located within cellular portions of chondroblastoma containing diffuse heterogeneous infiltrates of mostly DOG1(-) chondroblasts, CD163(+) macrophages and multinucleated osteoclastic giant cells. Thus, chondroblastoma can be added to the tumours that are usually positive for DOG1, alongside gastrointestinal stromal tumour (GIST), rare solid-pseudopapillary neoplasms of the pancreas and exceptional mesenchymal tumours including uterine type retroperitoneal leiomyoma, peritoneal leiomyomatosis and synovial sarcoma.

Chondrogenesis of human mesenchymal stem cells mediated by the combination of SOX trio SOX5, 6, and 9 genes complexed with PEI-modified PLGA nanoparticles

Target gene transfection for desired cell differentiation has recently become a major issue in stem cell therapy. For the safe and stable delivery of genes into human mesenchymal stem cells (hMSCs), we employed a non-viral gene carrier system such as polycataionic polymer, poly(ethyleneimine) (PEI), polyplexed with a combination of SOX5, 6, and 9 fused to green fluorescence protein (GFP), yellow fluorescence protein (YFP), or red fluorescence protein (RFP) coated onto PLGA nanoparticles. The transfection efficiency of PEI-modified PLGA nanoparticle gene carriers was then evaluated to examine the potential for chondrogenic differentiation by carrying the exogenous SOX trio (SOX5, 6, and 9) in hMSCs. Additionally, use of PEI-modified PLGA nanoparticle gene carriers was evaluated to investigate the potential for transfection efficiency to increase the potential ability of chondrogenesis when the trio genes (SOX5, 6, and 9) polyplexed with PEI were delivered into hMSCs. SOX trio complexed with PEI-modified PLGA nanoparticles led to a dramatic increase in the chondrogenesis of hMSCs in in vitro culture systems. For the PEI/GFP and PEI/SOX5, 6, and 9 genes complexed with PLGA nanoparticles, the expressions of GFP as reporter genes and SOX9 genes with PLGA nanoparticles showed 80% and 83% of gene transfection ratios into hMSCs two days after transfection, respectively.

Expression of master regulatory genes controlling skeletal development in benign cartilage and bone forming tumors

Recent progress in skeletal molecular biology has led to the clarification of the transcriptional mechanisms of chondroblastic and osteoblastic lineage differentiation. Three master transcription factors-Sox9, Runx2, and Osterix-were shown to play an essential role in determining the skeletal progenitor cells' fate. The present study evaluates the expression of these factors in 4 types of benign bone tumors-chondromyxoid fibroma, chondroblastoma, osteoid osteoma, and osteoblastoma-using immunohistochemistry and tissue microarrays. Osteoid osteoma and osteoblastoma showed strong nuclear expression of Osterix and Runx2. In contrast, only a few chondroblastomas showed positive nuclear expression of Osterix. Strong nuclear expression of Sox9 was detected in all chondroblastomas, whereas nearly half of the osteoblastomas showed focal weak cytoplasmic expression of Sox9.

Sox9 expression is not limited to chondroid neoplasms: variable occurrence in other soft tissue and bone tumors with frequent expression by synovial sarcomas

The transcription factor Sox9 is known to play a crucial role in normal chondrogenesis, and antibodies against Sox9 have been proposed as a diagnostic tool for neoplasms with chondroid differentiation. However, the pattern of Sox9 immunohistochemical expression by other bone and soft tissue neoplasms, as well as its diagnostic specificity, remain unexplored. The authors have performed immunohistochemistry with antibodies against Sox9 in 106 chondroid and nonchondroid bone and soft tissue neoplasms. Moderate to intense Sox9 nuclear staining was observed in 14/20 chondrosarcomas (70%), and in 24/81 (29.6%) cases from a multitumor tissue microarray, which included 16/18 synovial sarcomas, 4/15 osteosarcomas, 2/5 peripheral primitive neuroectodermal tumor (PNET)/Ewing sarcomas, 1/1 mesenchymal chondrosarcoma, and 1/1 chondroblastoma. The results suggest that Sox9 usefulness in the diagnosis of chondroid tumors may be limited because of low sensitivity and specificity. The finding of Sox9 expression by 88.9% of synovial sarcomas represents a novel and striking observation, which deserves further investigation.