Clinicopathologic Features and Genetic Alterations of a Primary Osteosarcoma of the Uterine Corpus.

Primary osteosarcoma (OS) of the uterus is distinctly rare. We report a case of primary uterine OS with pulmonary metastasis in a 74-yr-old woman. Histopathologic features of the uterine tumor were in keeping with a pure chondroblastic OS composed of neoplastic cells with osteoblastic/chondroblastic differentiation and neoplastic bone formation. Despite treatment with Doxorubicin and Olaratumab and later with palliative radiation therapy, the patient died 7 mo after hysterectomy due to multiple distant metastases. A targeted next-generation sequencing assay based on a 637-gene panel was performed to analyze genetic alterations in this highly aggressive tumor, but no somatic mutations that are amenable to targeted therapy were detected. Rather, a 51-nucleotide deletion mutation including partial exon 2 of mediator complex subunit 12 (MED12), a gene commonly mutated in leiomyoma, breast fibroadenoma and phyllodes tumor, was identified. Given the MED12 mutation in this uterine OS, we propose possible mechanisms that account for the origin and development of this tumor.

Extremity gossypiboma mimicking sarcoma: case report and review.

A 70-year-old man with a history of bladder and colon cancer presented with an enlarging mass in his right lower extremity. Forty years before presentation, he had injured his right lower extremity in a motor vehicle accident. Imaging findings indicated suspected sarcoma, which led to biopsy. Biopsy and further surgical exploration revealed the presence of a surgical sponge and surrounding local inflammatory reaction. No neoplasm was found, and the sponge and involved tissues were removed. Gossypiboma is exceedingly rare in the extremities. Imaging of retained foreign material can appear suggestive of sarcoma because of strong inflammatory responses and local tissue mass-like derangement resulting in heterogeneous signal changes. Ultimately, biopsy must be performed to ensure that no oncological pathological condition is present.

Mutations Preventing Regulated Exon Skipping in MET Cause Osteofibrous Dysplasia.

The periosteum contributes to bone repair and maintenance of cortical bone mass. In contrast to the understanding of bone development within the epiphyseal growth plate, factors that regulate periosteal osteogenesis have not been studied as intensively. Osteofibrous dysplasia (OFD) is a congenital disorder of osteogenesis and is typically sporadic and characterized by radiolucent lesions affecting the cortical bone immediately under the periosteum of the tibia and fibula. We identified germline mutations in MET, encoding a receptor tyrosine kinase, that segregate with an autosomal-dominant form of OFD in three families and a mutation in a fourth affected subject from a simplex family and with bilateral disease. Mutations identified in all families with dominant inheritance and in the one simplex subject with bilateral disease abolished the splice inclusion of exon 14 in MET transcripts, which resulted in a MET receptor (MET(Δ14)) lacking a cytoplasmic juxtamembrane domain. Splice exclusion of this domain occurs during normal embryonic development, and forced induction of this exon-exclusion event retarded osteoblastic differentiation in vitro and inhibited bone-matrix mineralization. In an additional subject with unilateral OFD, we identified a somatic MET mutation, also affecting exon 14, that substituted a tyrosine residue critical for MET receptor turnover and, as in the case of the MET(Δ14) mutations, had a stabilizing effect on the mature protein. Taken together, these data show that aberrant MET regulation via the juxtamembrane domain subverts core MET receptor functions that regulate osteogenesis within cortical diaphyseal bone.

Extra-Axial Chordoma of the Hand.

Chordomas are low-grade malignant tumors that are locally aggressive and have the potential to metastasize. They most often occur in the sacrococcygeal and spheno-occipital portions of the vertebral column. Morphologically similar tumors have been found outside the axial skeleton and are referred to as extra-axial chordomas. Several case reports have described the radiologic, microscopic, and immunologic profiles of these tumors and their similarities to axial chordomas. The authors report a 24-year-old man who presented with a mass in his left hand and underwent surgical excision. Specimens stained positive for pancytokeratin, S100, and brachyury. Brachyury is a protein that is present during embryogenesis and is expressed by chordomas. This is the first report of an extra-axial chordoma within the interosseous muscle compartment of the hand in a young patient.

Primary rhabdomyosarcoma of the distal femoral diaphysis: a case report and review of the literature.

Primary rhabdomyosarcoma of the bone is an extremely rare condition with few examples reported in the literature. We present the case of a 34-year-old male who presented with a lesion in the distal femur with initial imaging features consistent with Ewing sarcoma. Histologically, the lesion consisted of atypical pleomorphic polygonal rhabdomyoblasts demonstrating focal desmin and myogenin expression. A diagnosis of pleomorphic rhabdomyosarcoma was rendered. Despite systemic treatment and surgery, this patient experienced a rapidly progressive disease course. We believe this is only the second report in the orthopedic literature of a case of primary pleomorphic rhabdomyosarcoma of the bone. The key imaging, pathologic, and clinical findings are discussed.

PD-1, PD-L1, PD-L2 expression in the chordoma microenvironment.

Chordomas are rare malignant tumors that are postulated to arise from remnants of the notochord. Currently, the interaction between chordomas and the host immune system is poorly understood. The checkpoint protein, PD-1 is expressed by circulating lymphocytes and is a marker of activation and exhaustion. Its ligands, PD-L1 (B7-H1, CD274) and PD-L2 (B7-DC, CD273), are expressed on a variety of human cancers; however this pathway has not been previously reported in chordomas. We used flow cytometric and RT-PCR analysis in three established primary and recurrent chordoma cell lines (U-CH1, U-CH2, and JHC7) as well as immunohistochemical analysis of chordoma tissues from 10 patients to identify and localize expression of PD-1 pathway proteins. PD-1 ligands are not constitutively expressed by chordoma cells, but their expression is induced in the setting of pro-inflammatory cytokines in all cell lines examined. In paraffin embedded tissues, we found that tumor infiltrating lymphocytes expressed PD-1 in 3/6 cases. We also found that, although chordoma cells did not express significant levels of PD-L1, PD-L1 expression was observed on tumor-infiltrating macrophages and tumor infiltrating lymphocytes. Our study suggests that PD-1, PD-L1, and PD-L2 are present in the microenvironment of a subset of chordomas analyzed. Future studies are needed to evaluate the contribution of the PD-1 pathway to the immunosuppressive microenvironment of chordomas.

Bulbous epiphysis and popcorn calcification as related to growth plate differentiation in osteogenesis imperfecta.

BACKGROUND: Osteogenesis Imperfecta (OI) is an heritable systemic disorder of connective tissue due to different sequence variants in genes affecting both the synthesis of type I collagen and osteoblast function. Dominant and recessive inheritance is recognized. Approximately 90% of the OI cases are due to mutations in COL1A1/A2 genes. We clinically and radiologically describes an adult male with type III osteogenesis imperfecta who presents a rare bone dysplasia termed bulbous epiphyseal deformity in association with popcorn calcifications. Popcorn calcifications may occur with bulbous epiphyseal deformity or independently. METHODS: Molecular analysis was performed for COL1A1, COL1A2, LEPRE1 and WNT1 genes. RESULTS: An uncommon COL1A1 mutation was identified. Clinical and radiological exams confirmed a distinctive bulbous epiphyseal deformity with popcorn calcifications in distal femurs. We have identified four additional OI patients reported in current literature, whose X-rays show bulbous epiphyseal deformity related to mutations in CR-TAP, LEPRE1 and WNT1 genes. CONCLUSION: The mutation identified here had been previously described twice in OI patients and no previous correlation with bulbous epiphyseal deformity was described. The occurrence of this bone dysplasia focuses attention on alterations in normal growth plate differentiation and the subsequent effect on endochondral bone formation in OI.

Alveolar soft-part sarcoma in the sacrum: a case report and review of the literature.

Alveolar soft part sarcoma (ASPS) is a rare disease of the soft tissue. Although the disease is rare, it is refractory to chemotherapy and radiation. En bloc surgical resection offers the best chance of cure. In this article we report the case of a 28-year-old woman who presented with buttock and leg pain, bowel, bladder and gait impairment and a large mass in the sacrum. Following surgical excision, the lesion was proven to be ASPS. On pathology, the mass was TFE3 (transcription factor E3) positive, indicating the presence of the ASPL-TFE3 (novel gene-transcription factor) translocation. Following surgery, the patient had improvement in her pain and ambulation; however, she refused adjuvant therapy to pursue hospice care and succumbed to her disease 2 years after surgery. On a review of the literature, it was found that ASPS of the bone constitutes a rare and formidable subset of this disease. Further, metastases related to ASPS are common in the lungs, liver, brain, and lymph nodes. The degree of dissemination is a predictor of outcome, with 5-year survival of 81-88% in patients with local disease and only 20-46% in patients with metastatic disease at the time of presentation. Brain metastases at the time of presentation portend the worst prognosis.

TrkA + sensory neurons regulate osteosarcoma proliferation and vascularization to promote disease progression.

Bone pain is a presenting feature of bone cancers such as osteosarcoma (OS), relayed by skeletal-innervating peripheral afferent neurons. Potential functions of tumor-associated sensory neurons in bone cancers beyond pain sensation are unknown. To uncover neural regulatory functions, a chemical-genetic approach in mice with a knock-in allele for TrkA was used to functionally perturb sensory nerve innervation during OS growth and disease progression. TrkA inhibition in transgenic mice led to significant reductions in sarcoma-associated sensory innervation and vascularization, tumor growth and metastasis, and prolonged overall survival. Single-cell transcriptomics revealed that sarcoma denervation was associated with phenotypic alterations in both OS tumor cells and cells within the tumor microenvironment, and with reduced calcitonin gene-related peptide (CGRP) and vascular endothelial growth factor (VEGF) signaling. Multimodal and multi-omics analyses of human OS bone samples and human dorsal root ganglia neurons further implicated peripheral innervation and neurotrophin signaling in OS tumor biology. In order to curb tumor-associated axonal ingrowth, we next leveraged FDA-approved bupivacaine liposomes leading to significant reductions in sarcoma growth, vascularity, as well as alleviation of pain. In sum, TrkA-expressing peripheral neurons positively regulate key aspects of OS progression and sensory neural inhibition appears to disrupt calcitonin receptor signaling (CALCR) and VEGF signaling within the sarcoma microenvironment leading to significantly reduced tumor growth and improved survival. These data suggest that interventions to prevent pathological innervation of osteosarcoma represent a novel adjunctive therapy to improve clinical outcomes and survival.

Advanced Ultrasonic Inspection of Thick-Section Composite Structures for In-Field Asset Maintenance.

An investigation into the inspection capabilities of in-field advanced ultrasound detection for use on ultra-thick (20 to 100 mm) glass fibre-reinforced polyester composites is presented. Plates were manufactured using custom moulding techniques, such that delamination flaws were created at calibrated depths. The full matrix capture technique with an on-board total focussing method was used to detect flaws scanned by a 0.5 MHz linear array probe. Flaw through-thickness dimensions were altered to assess the threshold for crack face separation at which delaminations could be identified. Furthermore, part thickness and in-plane flaw dimensions were varied to identify the inspection capability limitations of advanced ultrasonics for thick composites. The results presented in this study demonstrate an inverse relationship between the ability to find delaminations and plate thicknesses, with inspections successful at depths up to 74 mm. When the delamination thickness exhibited surface-to-surface contact, the inspection capability was reduced to 35 mm. There was an exponential decay relationship between the accuracy of the flaw depth measurement and plate thickness, likely due to the necessity of low probe frequencies. The effective inspection depth was determined to be in the range of 1 to 20 times the wavelength. It is speculated that the accuracy of measurements could be improved using probes with novel coupling solutions, and detectors with optimised signal processing/filtration algorithms.

Conventional Chondrosarcoma with Clear Cell Features in the Rib: Report of Two Cases and Review of the Literature.

A subset of clear cell chondrosarcomas may contain focal areas of low-grade conventional chondrosarcoma; however, it is rare to find foci resembling clear cell chondrosarcoma admixed with areas otherwise typical conventional chondrosarcoma. We report two patients with conventional chondrosarcoma with clear cell features occurring in the rib, one in the setting of multiple hereditary exostoses (MHE) and the other without MHE. Both patients were found to have a destructive rib mass with a soft tissue component and underwent en bloc resection. Histologic examination revealed predominantly grade 2 conventional chondrosarcomas; however, multiple foci containing large cells with pale eosinophilic to clear cytoplasm, distinct cell borders, centrally located nuclei, and conspicuous nucleoli, resembling clear cell chondrosarcoma were identified throughout the specimen. The significance of clear cell features in an otherwise typical conventional chondrosarcoma, to our knowledge, is unknown and deserves recognition. Finally, these tumors highlight the need for careful histologic examination and proper classification as unexpected findings may impact management.

CNTNAP4 signaling regulates osteosarcoma disease progression.

Improved treatment strategies for sarcoma rely on clarification of the molecular mediators of disease progression. Recently, we reported that the secreted glycoprotein NELL-1 modulates osteosarcoma (OS) disease progression in part via altering the sarcomatous extracellular matrix (ECM) and cell-ECM interactions. Of known NELL-1 interactor proteins, Contactin-associated protein-like 4 (Cntnap4) encodes a member of the neurexin superfamily of transmembrane molecules best known for its presynaptic functions in the central nervous system. Here, CRISPR/Cas9 gene deletion of CNTNAP4 reduced OS tumor growth, sarcoma-associated angiogenesis, and pulmonary metastases. CNTNAP4 knockout (KO) in OS tumor cells largely phenocopied the effects of NELL-1 KO, including reductions in sarcoma cell attachment, migration, and invasion. Further, CNTNAP4 KO cells were found to be unresponsive to the effects of NELL-1 treatment. Transcriptomic analysis combined with protein phospho-array demonstrated notable reductions in the MAPK/ERK signaling cascade with CNTNAP4 deletion, and the ERK1/2 agonist isoproterenol restored cell functions among CNTNAP4 KO tumor cells. Finally, human primary cells and tissues in combination with sequencing datasets confirmed the significance of CNTNAP4 signaling in human sarcomas. In summary, our findings demonstrate the biological importance of NELL-1/CNTNAP4 signaling axis in disease progression of human sarcomas and suggest that targeting the NELL-1/CNTNAP4 signaling pathway represents a strategy with potential therapeutic benefit in sarcoma patients.

Interobserver reliability in the histopathological diagnosis of cartilaginous tumors in patients with multiple osteochondromas.

The distinction between benign and malignant cartilaginous tumors located peripherally in the bone may be a challenging task in surgical pathology. The aim of this study was to investigate interobserver reliability in histological diagnosis of cartilaginous tumors in the setting of multiple osteochondromas and to evaluate possible histological parameters that could differentiate among osteochondroma, low- and high-grade secondary peripheral chondrosarcoma. Interobserver reliability was assessed by 12 specialized bone-tumor pathologists in a set of 38 cases. Substantial agreement on diagnosis among all the reviewers was observed (intraclass correlation coefficient=0.78). Our study confirmed that mitotic figures and nuclear pleomorphism are hallmarks of high-grade secondary peripheral chondrosarcoma. However, despite the substantial agreement, we demonstrated that histology alone cannot distinguish osteochondroma from low-grade secondary peripheral chondrosarcoma in the setting of multiple osteochondromas, as nodularity, the presence of binucleated cells, irregular calcification, cystic/mucoid changes and necrosis were not helpful to indicate malignant transformation of an osteochondroma. On the other hand, among the concordant cases, the cartilage cap in osteochondroma was significantly less thicker than in low- and high-grade secondary peripheral chondrosarcoma. Therefore, our study showed that a multidisciplinary approach integrating clinical and radiographical features and the size of the cartilaginous cap in combination with a histological assessment are crucial to the diagnosis of cartilaginous tumors.

Grade 1 and 2 Chondrosarcomas of the Chest Wall: CT Imaging Features and Review of the Literature.

The purpose of our retrospective article is to review the CT imaging features of chondrosarcomas of the chest wall with pathologic correlation. For 26 subjects with biopsy-proven chondrosarcomas of the chest wall, two musculoskeletal radiologists retrospectively reviewed 26 CT scans in consensus. Descriptive statistics were performed. The mean tumor size was 57 mm. Twenty (20/26, 77%) chondrosarcomas were located in the ribs and six (6/26, 23%) in the sternum. The majority were lytic (19/26, 73%) with <25% calcification (15/26, 58%), and with a soft tissue mass (22/27, 85%). In this study CT features of grade 1 chondrosarcoma overlapped with those of grade 2 tumors. In conclusion, chondrosarcomas of the chest wall are generally lytic with an associated soft tissue mass, showing little calcified matrix and low-to-intermediate grade.

NELL1 Regulates the Matrisome to Promote Osteosarcoma Progression.

Sarcomas produce an abnormal extracellular matrix (ECM), which in turn provides instructive cues for cell growth and invasion. Neural EGF like-like molecule 1 (NELL1) is a secreted glycoprotein characterized by its nonneoplastic osteoinductive effects, yet it is highly expressed in skeletal sarcomas. Here, we show that genetic deletion of NELL1 markedly reduces invasive behavior across human osteosarcoma (OS) cell lines. NELL1 deletion resulted in reduced OS disease progression, inhibiting metastasis and improving survival in a xenograft mouse model. These observations were recapitulated with Nell1 conditional knockout in mouse models of p53/Rb-driven sarcomagenesis, which reduced tumor frequency and extended tumor-free survival. Transcriptomic and phosphoproteomic analyses demonstrated that NELL1 loss skews the expression of matricellular proteins associated with reduced FAK signaling. Culturing NELL1 knockout sarcoma cells on wild-type OS-enriched matricellular proteins reversed the phenotypic and signaling changes induced by NELL1 deficiency. In sarcoma patients, high expression of NELL1 correlated with decreased overall survival. These findings in mouse and human models suggest that NELL1 expression alters the sarcoma ECM, thereby modulating cellular invasive potential and prognosis. Disruption of NELL1 signaling may represent a novel therapeutic approach to short-circuit sarcoma disease progression. SIGNIFICANCE: NELL1 modulates the sarcoma matrisome to promote tumor growth, invasion, and metastasis, identifying the matrix-associated protein as an orchestrator of cell-ECM interactions in sarcomagenesis and disease progression.

Acetabular Reaming Is a Reliable Model to Produce and Characterize Periarticular Heterotopic Ossification of the Hip.

Heterotopic ossification (HO) is a pathologic process characterized by the formation of bone tissue in extraskeletal locations. The hip is a common location of HO, especially as a complication of arthroplasty. Here, we devise a first-of-its-kind mouse model of post-surgical hip HO and validate expected cell sources of HO using several HO progenitor cell reporter lines. To induce HO, an anterolateral surgical approach to the hip was used, followed by disclocation and acetabular reaming. Animals were analyzed with high-resolution roentgenograms and micro-computed tomography, conventional histology, immunohistochemistry, and assessments of fluorescent reporter activity. All the treated animals' developed periarticular HO with an anatomical distribution similar to human patients after arthroplasty. Heterotopic bone was found in periosteal, inter/intramuscular, and intracapsular locations. Further, the use of either PDGFRα or scleraxis (Scx) reporter mice demonstrated that both cell types gave rise to periarticular HO in this model. In summary, acetabular reaming reproducibly induces periarticular HO in the mouse reproducing human disease, and with defined mesenchymal cellular contributors similar to other experimental HO models. This protocol may be used in the future for further detailing of the cellular and molecular mediators of post-surgical HO, as well as the screening of new therapies.

NGF-p75 signaling coordinates skeletal cell migration during bone repair.

Bone regeneration following injury is initiated by inflammatory signals and occurs in association with infiltration by sensory nerve fibers. Together, these events are believed to coordinate angiogenesis and tissue reprogramming, but the mechanism of coupling immune signals to reinnervation and osteogenesis is unknown. Here, we found that nerve growth factor (NGF) is expressed following cranial bone injury and signals via p75 in resident mesenchymal osteogenic precursors to affect their migration into the damaged tissue. Mice lacking Ngf in myeloid cells demonstrated reduced migration of osteogenic precursors to the injury site with consequently delayed bone healing. These features were phenocopied by mice lacking p75 in Pdgfra+ osteoblast precursors. Single-cell transcriptomics identified mesenchymal subpopulations with potential roles in cell migration and immune response, altered in the context of p75 deletion. Together, these results identify the role of p75 signaling pathway in coordinating skeletal cell migration during early bone repair.

Imaging features of chondrosarcoma.

Chondrosarcomas are malignant neoplasms of mesenchymal origin and represent a heterogeneous group of tumors ranging from indolent, low-grade lesions to aggressive, high-grade neoplasms. The early diagnosis and treatment of chondrosarcomas is paramount to achieving a better prognosis. Multiple imaging modalities have been used for the purpose of initial detection, characterization, and staging, as well as for the performance of image-guided biopsies. As imaging techniques continue to evolve, radiologists are assuming an increasingly important role in the management of chondrosarcomas. This review describes the imaging characteristics of chondrosarcomas on multiple modalities and emphasizes the imaging features that may assist in differentiating these tumors from their benign counterparts, enchondromas and osteochondromas, which frequently still pose challenging diagnostic dilemmas.

Genetic diseases of bones and joints.

Genetic factors play roles in many diseases. Often these factors are ill defined and unpredictable. Other diseases are caused by specific single gene mutations and are passed to offspring in Mendelian inheritance patterns. There are over 5000 documented Mendelian disorders; over 500 of these affect bones and joints. Some of these single gene disorders affect many tissues, and the skeletal system is one of many organ systems involved. The surgical pathologist must often diagnose these disorders. Important examples are neurofibromatosis, Gaucher's disease, and alkaptonuria. Other single gene disorders almost exclusively affect the skeleton. These disorders are the skeletal dysplasias and 372 have been documented. These disorders are classified using radiographic, clinical, and molecular data. The most common dysplasias are osteogenesis imperfecta, achondroplasia, and osteopetrosis. The surgical pathologist usually does not play a role in the diagnosis of skeletal dysplasias. However, histologic studies often elucidate the pathophysiologic basis of these diseases and proper collection of tissues is important for the evolving understanding of the molecular basis of these disorders.