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

Acute Bone Loss and Infrapatellar Fat Pad Fibrosis in the Knee After an In Vivo ACL Injury in Adolescent Mice

BACKGROUND

Young patients are 6 times more likely than adults to have a primary anterior cruciate ligament (ACL) graft failure. Biological factors (ie, tunnel osteolysis) may account for up to a third of these failures. Previous evaluations of patient ACL explants indicated significant bone loss within the entheseal regions. However, it remains unknown if the degree of bone loss within the ACL insertion regions, wherein ACL grafts are fixated, exceeds that of the femoral and tibial condylar bone.

HYPOTHESIS

Bone loss in the mineralized matrices of the femoral and tibial ACL entheses is distinct from that clinically reported across the whole knee after injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

We developed a clinically relevant in vivo mouse ACL injury model to cross-sectionally track the morphological and physiological postinjury changes within the ACL, femoral and tibial entheses, synovial joint space, and load-bearing epiphyseal cortical and trabecular bone components of the knee joint. Right ACLs of 10-week-old C57BL/6J female mice (N = 75) were injured in vivo with the contralateral ACLs serving as controls. Mice were euthanized at 1, 3, 7, 14, or 28 days after injury (n = 12/cohort). Downstream analyses included volumetric cortical and trabecular bone analyses and histopathologic assessments of the knee joint after injury. Gait analyses across all time points were also performed (n = 15 mice).

RESULTS

The majority of the ACL injuries in mice were partial tears. The femoral and tibial cortical bone volumes were 39% and 32% lower, respectively, at 28 days after injury than those of the uninjured contralateral knees (P < .01). Trabecular bone measures demonstrated little difference between injured and control knees after injury. Across all bone measures, bone loss was similar between the injured knee condyles and ACL entheses. There was also significant inflammatory activity within the knee after injury. By 7 days after injury, synovitis and fibrosis were sigificantly elevated in the injured knee compared with the controls (P < .01), which corresponded with significantly higher osteoclast activity in bone at this time point compared with the controls. This inflammatory response signficantly persisted throughout the duration of the study (P < .01). The hindlimb gait after injury deviated from normal, but mice habitually loaded their injured knee throughout the study.

CONCLUSION

Bone loss was acute and persisted for 4 weeks after injury in mice. However, the authors' hypothesis was not confirmed, as bone quality was not significantly lower in the entheses compared with the condylar bone regions after injury. With relatively normal hindlimb loading but a significant physiological response after injury, bone loss in this model may be driven by inflammation.

CLINICAL RELEVANCE

There is persistent bone resorption and fibrotic tissue development after injury that is not resolved. Inflammatory and catabolic activity may have a significant role in the postinjury decline of bone quality in the knee.

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.

Synchronous chondroblastomas in the knee joint: A case report

Introduction

A chondroblastoma (CB) is a benign chondroid bone tumor that typically arises in growing children. It frequently occurs in the proximal tibia, femur, and humerus. However, the biological behavior of CBs remains unclear because of their rarity. Herein, we report a rare case of synchronous CBs arising on the bilateral sides of the knee joint, suggesting the etiology of chronological tumorigenesis.

Presentation of case

An 18-year-old Japanese man with a complaint of right knee pain was referred to our hospital. Radiography revealed an expanding osteolytic lesion in the right proximal tibia. A small lesion in the distal femur was detected on magnetic resonance imaging. A biopsy of the tibial lesion revealed a pathological diagnosis of CB. Two-stage curettages were performed in the tibia and femur, and the pathological diagnosis of the femoral lesion was CB. No recurrence had occurred for 5 years in the tibia and a year in the femur with stable ambulation and a full range of motion.

Discussion

In our case, the CBs in the proximal tibia and distal femur co-occurred, suggesting that the seed of the CB emerged before the separation of these two bones. The key point to the generation of CB is that its origin could be initiated during mesenchymal condensation before the separation and differentiation of bones as if continental drifts.

Conclusion

We experienced a rare and suggestive case in CB etiology. An experience of synchronous CBs in the consecutive bones was suggestive of CB etiology and careful management.

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Report of a rare type of chondroblastomas in two consecutive long bones.

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Tumorigenesis of chondroblastoma is suggested at mesenchymal condensation.

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Chondroblastoma separation to different bones, resembling plate tectonics.

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Multiple chondroblastomas should be carefully treated or monitored.

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.

Femur Neck Osteoid Osteoma Managed with Radiofrequency Ablation - A Case Report

Introduction

Osteoid osteoma is a benign tumor of bones involving mainly the tubular bones and rarely axial skeletons. The patient mainly complains of night pain in the affected region or the joint nearby. Pain always subsides with analgesics and gradually increased over the period of time. It is mostly missed on the plain radiograph so magnetic resonance imaging or computed tomography (CT) scan are preferred for accurate and early diagnosis of the tumor.

Case Report

A 20-year-old male presented with pain in the left hip region which was gradually increased over the period of 6 months and was experiencing pain more in the night, used to relieve on medications. CT scan of the left hip showed the presence of osteoid osteoma of 0.5 cm diameter, which was managed with radiofrequency ablation. Moreover, the patient had pain relief immediately after the procedure. At present 1-year follow-up, the patient is symptomless with no recurrence.

Conclusion

The neck of femur osteoid osteomas is best managed with radiofrequency ablation as it causes less morbidity to the patient and helps in early return to normal activities with fewer complications as compared to open procedures.

Recent Advances of Osterix Transcription Factor in Osteoblast Differentiation and Bone Formation

With increasing life expectations, more and more patients suffer from fractures either induced by intensive sports or other bone-related diseases. The balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption is the basis for maintaining bone health. Osterix (Osx) has long been known to be an essential transcription factor for the osteoblast differentiation and bone mineralization. Emerging evidence suggests that Osx not only plays an important role in intramembranous bone formation, but also affects endochondral ossification by participating in the terminal cartilage differentiation. Given its essentiality in skeletal development and bone formation, Osx has become a new research hotspot in recent years. In this review, we focus on the progress of Osx's function and its regulation in osteoblast differentiation and bone mass. And the potential role of Osx in developing new therapeutic strategies for osteolytic diseases was discussed.

An extraskeletal osteosarcoma in the auricle of a Wistar Hannover rat

An extraskeletal osteosarcoma was detected in the auricle of a 110-week-old female Wistar Hannover rat. Grossly, the tumor, measuring 15 mm in size, was observed in the subcutis as a solid and hard mass. Histologically, the majority of the mass comprised mature, compact bone. It was surrounded by neoplastic cells showing a variety of histologies, such as sarcoma, not otherwise specified, and myxosarcoma away from the bone-forming region. However, these different histological regions were considered to be components of a single bone tumor, based on the common expression of osterix and a similar mixture of constituent cells in each region. The tumor was diagnosed as an extraskeletal osteosarcoma because of the presence of infiltrative growth and abnormal mitosis and its development in the auricle without attachment to the skeleton. The present case is a rare histological type of an extraskeletal osteosarcoma with independent and different histological elements in rats.

Osteoid osteoma: Contemporary management

Osteoid osteoma is a benign bone-forming tumor with hallmark of tumor cells directly forming mature bone. Osteoid osteoma accounts for around 5% of all bone tumors and 11% of benign bone tumors with a male predilection. It occurs predominantly in long bones of the appendicular skeleton. According to Musculoskeletal Tumor Society staging system for benign tumors, osteoid osteoma is a stage-2 lesion. It is classified based on location as cortical, cancellous, or subperiosteal. Nocturnal pain is the most common symptom that usually responds to salicyclates and non-steroidal anti-inflammatory medications. CT is the modality of choice not only for diagnosis but also for specifying location of the lesion, i.e. cortical vs sub periosteal or medullary. Non-operative treatment can be considered as an option since the natural history of osteoid osteoma is that of spontaneous healing. Surgical treatment is an option for patients with severe pain and those not responding to NSAIDs. Available surgical procedures include radiofrequency (RF) ablation, CT-guided percutaneous excision and en bloc resection.

Bone-Forming Tumors

Bone-forming tumors are defined by neoplastic cells that differentiate along the lines of osteoblasts that deposit neoplastic bone. The morphology and biological spectrum of bone-forming tumors is broad, and their accurate diagnosis requires the careful correlation of their clinical, morphologic, and radiologic characteristics. Immunohistochemical and molecular analyses have an important role in select instances. At present, the identification of neoplastic bone largely depends on histologic analysis, which can be subjective. The major types of osteosarcoma are defined according to their morphology, origin within or on the surface of the bone, and their histologic grade.

Regulation of Bone Metabolism

Bone is formed through the processes of endochondral and intramembranous ossification. In endochondral ossification primary mesenchymal cells differentiate to chondrocytes and then are progressively substituted by bone, while in intramembranous ossification mesenchymal stem cells (MSCs) differentiate directly into osteoblasts to form bone. The steps of osteogenic proliferation, differentiation, and bone homeostasis are controlled by various markers and signaling pathways. Bone needs to be remodeled to maintain integrity with osteoblasts, which are bone-forming cells, and osteoclasts, which are bone-degrading cells.In this review we considered the major factors and signaling pathways in bone formation; these include fibroblast growth factors (FGFs), bone morphogenetic proteins (BMPs), wingless-type (Wnt) genes, runt-related transcription factor 2 (RUNX2) and osteoblast-specific transcription factor (osterix or OSX).

Osteogenic tumour in Australopithecus sediba: Earliest hominin evidence for neoplastic disease

Abstract We describe the earliest evidence for neoplastic disease in the hominin lineage. This is reported from the type specimen of the extinct hominin Australopithecus sediba from Malapa, South Africa, dated to 1.98 million years ago. The affected individual was male and developmentally equivalent to a human child of 12 to 13 years of age. A penetrating lytic lesion affected the sixth thoracic vertebra. The lesion was macroscopically evaluated and internally imaged through phase-contrast X-ray synchrotron microtomography. A comprehensive differential diagnosis was undertaken based on gross- and micro-morphology of the lesion, leading to a probable diagnosis of osteoid osteoma. These neoplasms are solitary, benign, osteoid and bone-forming tumours, formed from well-vascularised connective tissue within which there is active production of osteoid and woven bone. Tumours of any kind are rare in archaeological populations, and are all but unknown in the hominin record, highlighting the importance of this discovery. The presence of this disease at Malapa predates the earliest evidence of malignant neoplasia in the hominin fossil record by perhaps 200 000 years.

Haploinsufficiency for either one of the type-II regulatory subunits of protein kinase A improves the bone phenotype of Prkar1a+/- mice

Carney Complex (CNC), a human genetic syndrome predisposing to multiple neoplasias, is associated with bone lesions such as osteochondromyxomas (OMX). The most frequent cause for CNC is PRKAR1A deficiency; PRKAR1A codes for type-I regulatory subunit of protein kinase A (PKA). Prkar1a(+/-) mice developed OMX, fibrous dysplasia-like lesions (FDL) and other tumors. Tumor tissues in these animals had increased PKA activity due to an unregulated PKA catalytic subunit and increased PKA type II (PKA-II) activity mediated by the PRKAR2A and PRKAR2B subunits. To better understand the effect of altered PKA activity on bone, we studied Prkar2a and Prkar2b knock out (KO) and heterozygous mice; none of these mice developed bone lesions. When Prkar2a(+/-) and Prkar2b(+/-) mice were used to generate Prkar1a(+/-)Prkar2a(+/-) and Prkar1a(+/-)Prkar2b(+/-) animals, bone lesions formed that looked like those of the Prkar1a(+/-) mice. However, better overall bone organization and mineralization and fewer FDL lesions were found in both double heterozygote groups, indicating a partial restoration of the immature bone structure observed in Prkar1a(+/-) mice. Further investigation indicated increased osteogenesis and higher new bone formation rates in both Prkar1a(+/-)Prkar2a(+/-) and Prkar1a(+/-)Prkar2b(+/-) mice with some minor differences between them. The observations were confirmed with a variety of markers and studies. PKA activity measurements showed the expected PKA-II decrease in both double heterozygote groups. Thus, haploinsufficiency for either of PKA-II regulatory subunits improved bone phenotype of mice haploinsufficient for Prkar1a, in support of the hypothesis that the PRKAR2A and PRKAR2B regulatory subunits were in part responsible for the bone phenotype of Prkar1a(+/-) mice.

Bone- and cartilage-forming tumors and ewing sarcoma: an update with a gnathic emphasis

Over the past decade, there have been remarkable advances in bone tumor pathology. Insights into the genetic basis and pathobiology of many tumor types have impacted diagnosis, classification, and treatment. However, because gnathic lesions may comprise only a small proportion of cases overall for many tumors, clinicopathologic features and management considerations specific to this subset may be overlooked. Here we provide a summary of recent developments in the following tumor types: osteosarcoma (OS), chondrosarcoma (CS), osteoid osteoma (OO), osteoblastoma (OB), and Ewing sarcoma (ES). In particular, we will give special consideration to cases arising in the jaws.

Expired and Pathogen-Inactivated Platelet Concentrates Support Differentiation and Immunomodulation of Mesenchymal Stromal Cells in Culture

Platelet lysates have been reported as suitable cell culture supplement for cultures of mesenchymal stromal cells (MSCs). The demand for safe and animal-free cultures of MSCs is linked to the potential application of MSCs in clinics. While the use of platelet lysates offers an alternative to animal serum in MSC cultures, obtaining supplies of fresh platelet concentrates for lysate production is challenging and raises concerns due to the already existing shortage of platelet donors. We have previously demonstrated that expired platelet concentrates may represent a good source of platelets for lysate production without competing with blood banks for platelet donors. The INTERCEPT Blood System™ treatment of platelet concentrates allows for prolonged storage up to 7 days, using highly specific technology based on amotosalen and UV-A light. The INTERCEPT system has therefore been implemented in blood processing facilities worldwide. In this study, we evaluated the suitability of INTERCEPT-treated, expired platelet concentrates, processed into platelet lysates, for the culture of MSCs compared to nontreated expired platelets. Bone marrow-derived MSCs were cultured in media supplemented with either platelet lysates from traditionally prepared expired platelet concentrates or in platelet lysates from expired and pathogen-inactivated platelet concentrates. The effects of pathogen inactivation on the ability of the platelets to support MSCs in culture were determined by evaluating MSC immunomodulation, immunophenotype, proliferation, and trilineage differentiation. Platelet lysates prepared from expired and pathogen-inactivated platelet concentrates supported MSC differentiation and immunosuppression better compared to traditionally prepared platelet lysates from expired platelet units. Pathogen inactivation of platelets with the INTERCEPT system prior to use in MSC culture had no negative effects on MSC immunophenotype or proliferation. In conclusion, the use of expired pathogen-inactivated platelet units from blood banks to prepare platelet lysates for the culture of MSCs is desirable and attainable.

Osteoblastoma of the lateral skull base: work-up, surgical management, and a review of the literature"

Objectives To describe the work-up and surgical management of an osteoblastoma involving the lateral skull base. Typically occurring in the spine or long bones, osteoblastomas of the craniofacial skeleton are exceedingly rare and infrequently reported. A review of the current literature regarding temporal bone osteoblastoma, diagnosis, and treatment is described. Methods This case report describes the clinical presentation, radiographic studies, surgical management, histology, and postoperative follow-up of a young man presenting to a tertiary care neurotology practice with osteoblastoma involving the lateral skull base. A review of the current literature regarding osteoblastoma of the skull base, work-up, and treatment is described. Results A 15-year-old adolescent boy with a greater than 1-year history of right-sided retroauricular pain, a palpable postauricular mass, and chronic headaches presented for evaluation/management. Microscope examination of the ears, hearing, and cranial nerve function were normal. High-resolution temporal bone computed tomography and magnetic resonance imaging scans were obtained, which revealed an expansile mass involving the junction of the temporal and occipital bones. The patient underwent a combined retrosigmoid/retrolabyrinthine resection of this extradural tumor. Histology revealed a benign bone neoplasm consistent with osteoblastoma. Complete surgical resection was achieved, and the patient's symptoms fully resolved. Follow-up imaging studies found no evidence of recurrence. The scientific literature relevant to work-up and management of osteoblastoma is reviewed. Discussion Osteoblastomas of the lateral skull base are rare, histologically benign tumors that can present with radiographic features suggestive of malignancy. An en bloc resection is important for both diagnosis and definitive treatment of these neoplasms. The differential diagnosis on imaging and histology is discussed.

SATB2 is a novel marker of osteoblastic differentiation in bone and soft tissue tumours

AIMS

Diagnosing osteosarcoma can be challenging, as osteoid deposition is often limited in extent, and hyalinized stroma may closely mimic osteoid. SATB2 is a nuclear protein that plays a critical role in osteoblast lineage commitment. The aim of this study was to examine SATB2 expression in osteosarcomas and other bone and soft tissue tumours, to evaluate its diagnostic utility.

METHODS AND RESULTS

Whole sections of 215 tumours were evaluated, including 52 osteosarcomas (43 of skeletal origin; nine extraskeletal), 86 other bone tumours, and 77 other soft tissue tumours. All skeletal osteosarcomas, osteoblastomas, osteoid osteomas, and fibrous dysplasias, eight (89%) extraskeletal osteosarcomas, five (83%) giant cell tumours and three (50%) chondromyxoid fibromas showed nuclear immunoreactivity for SATB2. Staining in other bone and soft tissue tumours was predominantly limited to areas of heterologous osteoblastic differentiation. Focal weak staining was identified in one (9%) unclassified pleomorphic sarcoma and one (13%) monophasic synovial sarcoma. SATB2 was negative in all soft tissue tumours with prominent sclerotic stromal collagen.

CONCLUSIONS

SATB2 is a marker of osteoblastic differentiation in benign and malignant mesenchymal tumours. Although SATB2 is not specific for osteosarcoma, it has the potential to be a useful adjunct in some settings, particularly in the distinction between hyalinized collagen and osteoid.

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.

Regulators of skeletal development: a cluster analysis of 206 bone tumors reveals diagnostically useful markers

The molecules Indian hedgehog (IHH), SP7 (also known as osterix), sex-determining region Y-box 9 (SOX9), runt-related transcription factor 2 (RUNX2) and TWIST1 regulate the normal differentiation of osteo- and chondrogenic cells from precursors during skeletal development and remodeling. The aberrant function of the same molecules has been implicated in the pathogenesis of bone tumors. Preliminary studies suggest that antibodies against these molecules have practical, diagnostic or prognostic utility in tumors. However, a comprehensive analysis of the expression of these molecules in a large, diverse set of bone tumors has yet to be reported. The goals of this study were to compare the immunohistochemical profiles of IHH, SP7, SOX9, RUNX2 and TWIST1 among bone tumors and to determine the optimum panel for diagnostic utility. Tissue microarrays prepared from 206 undecalcified tumors (71 osteosarcomas, 26 osteoblastomas/osteoid osteomas, 50 giant cell tumors, 5 chondromyxoid fibromas and 54 chondroblastomas) were stained with antibodies to IHH, SP7, SOX9, RUNX2 and TWIST1. The stains were scored for intensity (0-3+) and distribution. The results were analyzed by cluster analysis. Optimum antibody panels for diagnostic sensitivity and specificity were calculated. Analysis revealed six main clusters that corresponded well to tumor types and suggested a close relationship between the stromal cells of giant cell tumor and the osteoblasts of osteosarcoma. The expression profile of chondromyxoid fibroma and chondroblastoma also suggested related differentiation. The distribution of osteoblastomas and osteoid osteomas was more heterogeneous. RUNX2, SOX9 and TWIST1 represented the most sensitive and specific immunohistochemical panel to distinguish among these diagnoses with the limitation that no result could discriminate between chondroblastoma and chondromyxoid fibroma. IHH and SP7 did not yield additional utility.