Recurrent and novel fusions detected by targeted RNA sequencing as part of the diagnostic workflow of soft tissue and bone tumours.

The identification of gene fusions has become an integral part of soft tissue and bone tumour diagnosis. We investigated the added value of targeted RNA-based sequencing (targeted RNA-seq, Archer FusionPlex) to our current molecular diagnostic workflow of these tumours, which is based on fluorescence in situ hybridisation (FISH) for the detection of gene fusions using 25 probes. In a series of 131 diagnostic samples targeted RNA-seq identified a gene fusion, BCOR internal tandem duplication or ALK deletion in 47 cases (35.9%). For 74 cases, encompassing 137 FISH analyses, concordance between FISH and targeted RNA-seq was evaluated. A positive or negative FISH result was confirmed by targeted RNA-seq in 27 out of 49 (55.1%) and 81 out of 88 (92.0%) analyses, respectively. While negative concordance was high, targeted RNA-seq identified a canonical gene fusion in seven cases despite a negative FISH result. The 22 discordant FISH-positive analyses showed a lower percentage of rearrangement-positive nuclei (range 15-41%) compared to the concordant FISH-positive analyses (>41% of nuclei in 88.9% of cases). Six FISH analyses (in four cases) were finally considered false positive based on histological and targeted RNA-seq findings. For the EWSR1 FISH probe, we observed a gene-dependent disparity (p = 0.0020), with 8 out of 35 cases showing a discordance between FISH and targeted RNA-seq (22.9%). This study demonstrates an added value of targeted RNA-seq to our current diagnostic workflow of soft tissue and bone tumours in 19 out of 131 cases (14.5%), which we categorised as altered diagnosis (3 cases), added precision (6 cases), or augmented spectrum (10 cases). In the latter subgroup, four novel fusion transcripts were found for which the clinical relevance remains unclear: NAB2::NCOA2, YAP1::NUTM2B, HSPA8::BRAF, and PDE2A::PLAG1. Overall, targeted RNA-seq has proven extremely valuable in the diagnostic workflow of soft tissue and bone tumours.

Optical Genome Mapping for Comprehensive Cytogenetic Analysis of Soft-Tissue and Bone Tumors for Diagnostic Purposes.

Soft-tissue and bone tumors represent a heterogeneous group of tumors encompassing more than 100 histologic subtypes today. Identifying genetic aberrations increasingly is important in these tumors for accurate diagnosis. Although gene mutations typically are detected by second-generation sequencing, the identification of structural variants (SVs) and copy number alterations (CNAs) remains challenging and requires various cytogenetic techniques including karyotyping, fluorescence in situ hybridization, and arrays, each with important limitations. Optical Genome Mapping (OGM), a non-sequencing-based technique for high-resolution detection of SVs and CNAs, was applied in a retrospective series of diagnostic soft-tissue and bone tumor samples. Sample preparation was successful in 38 of 53 cases, with the highest success rate in nonadipocytic soft-tissue tumors (24 of 27 cases; 89%). In 32 of 35 cases carrying a diagnostic SV or CNA, OGM identified the aberration (91%), including a POU2AF3::EWSR1 fusion in a round cell sarcoma and a translocation t(1;5)(p22;p15) in a myxoinflammatory fibroblastic sarcoma. Interestingly, OGM shed light on the genomic complexity underlying the various aberrations. In five samples, OGM showed that chains of rearrangements generated the diagnostic fusion, three of which involved chromoplexy. In addition, in nine samples, chromothripsis was causal to the formation of giant marker/ring/double-minute chromosomes. Finally, compared with standard-of-care cytogenetics, OGM revealed additional aberrations, requiring further investigation of their potential clinical relevance.

Partial Femoral Diaphysectomy With Vastus Lateralis Interposition in a Paraplegic Patient With Severely Debilitating Hip Ankylosis: Low Risks and High Gains?

We present the case of a 56-year-old male unable to sit because of an ankylosed right hip. This ankylosis originated from combined neurogenic heterotopic ossifications (NHO) and traumatic heterotopic ossifications (THO) as a result of a road traffic accident. Because of multiple ossifications, the proximity of neurovascular structures, and chronic pressure ulcers, a resection was deemed unsafe. We opted for a new articulation distal to the ossifications in unstained tissue. A partial femoral diaphysectomy was performed just distal of the lesser trochanter. and the vastus lateralis was rotated in the new articulation. Postoperatively, the patient was able to sit as his hip could flex again. A partial femoral diaphysectomy with vastus lateralis interposition flap appears to be a valid option in paraplegic patients with extensive heterotopic ossifications (HO) in close proximity to neurovascular structures with a low risk of complications and high gain in hip mobility.

Advanced quantitative 3D imaging improves the reliability of the classification of acetabular defects.

INTRODUCTION: Classifying complex acetabular defects in revision total hip arthroplasty (THA) by means of conventional radiographs comes with significant limitations. Statistical shape modelling allows the virtual reconstruction of the native pelvic morphology, hereby enabling an analytic acetabular defect assessment. Our objective was to evaluate the effect of advanced imaging augmented with analytic representations of the defect on (1) intra- and inter-rater reliability, and (2) up- or downscaling of classification scores when evaluating acetabular defects in patients undergoing revision THA. MATERIALS AND METHODS: The acetabular defects of 50 patients undergoing revision THA were evaluated by three independent, fellowship-trained orthopaedic surgeons. Defects were classified according to the acetabular defect classification (ADC) using four different imaging-based representations, namely, standard radiographs, CT imaging, a virtual three-dimensional (3D) model and a quantitative analytic representation of the defect based on a statistical shape model reconstruction. Intra- and inter-rater reliabilities were quantified using Fleiss' and Cohen's kappa scores, respectively. Up- and downscaling of classification scores were compared for each of the imaging-based representations and differences were tested. RESULTS: Overall inter-rater agreement across all imaging-based representations for the classification was fair (κ 0.29 95% CI 0.28-0.30). Inter-rater agreement was lowest for radiographs (κ 0.21 95% CI 0.19-0.22) and increased for other representations with agreement being highest when using analytic defect models (κ 0.46 95% CI 0.43-0.48). Overall intra-rater agreement was moderate (κ 0.51 95% CI 0.42-0.60). Intra-rater agreement was lowest for radiographs (κ 0.40 95% CI 0.23-0.57), and highest for ratings including analytic defect models (κ 0.64:95% CI 0.46-0.82). Virtual 3D models with quantitative analytic defect representations upscaled acetabular defect scores in comparison to standard radiographs. CONCLUSIONS: Using 3D CT imaging with statistical shape models doubles the intra- and inter-rater reliability and results in upscaling of acetabular defect classification when compared to standard radiographs. This method of evaluating defects will aid in planning surgical reconstruction and stimulate the development of new classification systems based on advanced imaging techniques.

Fracture risk assessment and evaluation of femoroplasty in metastatic proximal femurs. An in vivo CT-based finite element study.

The goal of this study was twofold. First, we aimed to evaluate the accuracy of a finite element (FE) model to predict bone fracture in cancer patients with proximal femoral bone metastases. Second, we evaluated whether femoroplasty could effectively reduce fracture risk. A total of 89 patients were included, with 101 proximal femurs affected with bone metastases. The accuracy of the model to predict fracture was evaluated by comparing the FE failure load, normalized for body weight, against the actual occurrence of fracture during a 6-month follow-up. Using a critical threshold, the model could identify whether femurs underwent fracture with a sensitivity of 92% and a specificity of 66%. A virtual treatment with femoroplasty was simulated in a subset of 34 out of the 101 femurs; only femurs with one or more well-defined lytic lesions were considered eligible for femoroplasty. We modeled their lesions, as well as the surrounding 4 mm of trabecular bone, to be augmented with bone cement. The simulation of femoroplasty increased the median failure load of the FE model by 57% for lesions located in the head/neck of the femur. At this lesion location, all high risk femurs that had fractured during follow-up effectively moved from a failure load below the critical threshold to a value above. For lesions located in the trochanteric region, no definite improvement in failure load was found. Although additional validation studies are required, our results suggest that femoroplasty can effectively reduce fracture risk for several osteolytic lesions in the femoral head/neck.

An egg in the leg: Case report of an osteochondrolipoma.

Osteochondrolipomas, a very rare combination of chondroid and osseous differentiation within lipomas, are typically found in the neck and head area. We present the case of an osteochondrolipoma in the thigh of a 54-year-old female, with matching histological and cytological correlation. To the best of our knowledge, this atypical location has only been reported once in the literature.

Management of Synovial Sarcoma in a Tertiary Referral Center: A Retrospective Analysis of 134 Patients.

BACKGROUND: Synovial sarcomas (SS) are malignant mesenchymal neoplasms that account for about 10% of all sarcomas. Complete surgical excision is the mainstay of primary treatment for localized disease, but SS have a high tendency for local relapse and metastases. Metastatic disease is commonly treated with systemic chemotherapy. METHODS: We designed a retrospective analysis to describe the clinical presentation, course of treatment, outcome, and prognosis of patients with SS. Univariate and multivariate analyses were performed for potential prognostic factors. RESULTS: We identified 134 patients treated between 1987 and 2018, with a cutoff date of December 2018. Demographics, disease characteristics, treatment, and survival rates were collected and analyzed. The median overall survival (mOS) from the date of diagnosis was 96.7 months. The median progression-free survival was 6.37 months. Disease-free survival was 26 months. Age over 65 years was found to be a prognostic factor with statistically significant value in the univariate analysis regarding mOS (p = 0.015) and mOS after local relapse (p = 0.0228). CONCLUSIONS: Even though our study is limited by the retrospective nature of the analysis, it adds an important amount of clinical data regarding the treatment and outcome of SS.

Intraosseous schwannoma of the glenoid: case report and literature review.

Intraosseous schwannomas represent an extremely rare subgroup of schwannomas, accounting for <1% of all primary bone tumors. They mostly occur in the mandible, the maxilla, the sacrum, and they are also seen in long bones. We herein report a rare presentation of an intraosseous schwannoma in the glenoid of a 49-year-old patient. She complained of shoulder pain and was referred to the orthopaedic oncologist after detection of a suspicious lesion on imaging. Biopsy revealed benign spindle cells and immunohistochemistry was positive for S100. Because of the rarity of these intraosseous schwannomas it is important to recognize their radiological and histological features and make a differential diagnosis with other lytic tumors. Only if these characteristics are recognized, correct treatment can be given with definite curettage and bone grafting and correct follow-up with avoidance of unnecessary adjuvant therapy.

Establishment and Characterization of Histologically and Molecularly Stable Soft-tissue Sarcoma Xenograft Models for Biological Studies and Preclinical Drug Testing.

Soft-tissue sarcomas (STS) represent a heterogeneous group of rare, malignant tumors of mesenchymal origin. Reliable in vivo sarcoma research models are scarce. We aimed to establish and characterize histologically and molecularly stable patient-derived xenograft (PDX) models from a broad variety of STS subtypes. A total of 188 fresh tumor samples from consenting patients with localized or advanced STS were transplanted subcutaneously in NMRI-nu/nu-immunodeficient mice. Once tumor growth was observed, the material was passaged to a next generation of mice. A patient-derived tumor sample was considered "successfully engrafted" whenever the sample was transplanted to passage 1. A PDX model was considered "established" when observing stable morphologic and molecular features for at least two passages. With every passage, histologic and molecular analyses were performed. Specific genomic alterations and copy-number profile were assessed by FISH and low coverage whole-genome sequencing. The tumor engraftment rate was 32% (61/188) and 188 patient samples generated a total of 32 PDX models, including seven models of myxofibrosarcoma, five dedifferentiated liposarcoma, five leiomyosarcoma, three undifferentiated pleomorphic sarcoma, two malignant peripheral nerve sheet tumor models, and single models of synovial sarcoma and some other (ultra)rare subtypes. Seventeen additional models are in early stages of engraftment (passage 1-2). Histopathologic and molecular features were compared with the original donor tumor and were stable throughout passaging. The platform is used for studies on sarcoma biology and suited for in vivo preclinical drug testing as illustrated by a number of completed and ongoing laboratory studies.

The surgical treatment of acromioclavicular joint injuries.

Acromioclavicular joint (ACJ) injuries are common, but their incidence is probably underestimated. As the treatment of some sub-types is still debated, we reviewed the available literature to obtain an overview of current management.We analysed the literature using the PubMed search engine.There is consensus on the treatment of Rockwood type I and type II lesions and for high-grade injuries of types IV, V and VI. The treatment of type III injuries remains controversial, as none of the studies has proven a significant benefit of one procedure when compared with another.Several approaches can be considered in reaching a valid solution for treating ACJ lesions. The final outcome is affected by both vertical and horizontal post-operative ACJ stability. Synthetic devices, positioned using early open or arthroscopic procedures, are the main choice for young people.Type III injuries should be managed surgically only in cases with high-demand sporting or working activities. Cite this article: EFORT Open Rev 2017;2:432-437. DOI: 10.1302/2058-5241.2.160085.

Fungation in soft tissue sarcomas is associated with poor survival.

PURPOSE: Whilst much is known on the multiple variables associated with a poor prognosis in soft tissue sarcomas, little evidence exists on the impact of fungation at the time of presentation. The aim of this study was to assess the impact of fungation on overall and disease free survival in soft tissue sarcomas. METHODS: The study comprised a retrospective review of all patients presenting with a soft tissue sarcoma between 1996 and 2014 managed at a single institution. Over the 18-year study period, 2661 patients were diagnosed with a STS. Eighty-six patients (3.2%) presented with a fungating tumour. RESULTS: The five year survival for all patients with a fungating sarcoma was 15.5% (95% confidence interval: 4.6-26.4), which compared to 65.6% (95% confidence interval 63.2-67.8%) (p = 0.0001) for non-fungating tumours. The incidence of metastasis at presentation in the non-fungating tumour group was 11.3% of patients, compared to 20.0% in those with a fungating tumour (p = 0.0113). Factors associated with a poor prognosis in the fungating group included size, grade and tumour-type, patient age, tumour depth, and metastases at presentation. As an independent risk factor, tumour fungation was associated with a poor prognosis when compared to non-fungating tumours. The rate of limb sacrifice as primary treatment was higher in the fungating group (23% versus 73%). In spite of this, the incidence of local recurrence was higher in the fungating group (20% versus 16.5%). CONCLUSIONS: Fungation is associated with a poor prognosis with a high incidence of metastases at presentation and a high rate of local recurrence. As an independent variable, fungation confers a poor prognosis when compared to non-fungation in soft tissue sarcomas.

Does total humeral endoprosthetic replacement provide reliable reconstruction with preservation of a useful extremity?

BACKGROUND: Controversy exists regarding the ideal method of reconstruction after proximal humeral resection and several reconstructive techniques have been reported. The reconstructive options are very limited when resection of the entire humerus is required. One option is endoprosthetic reconstruction, but there have been few published studies on the outcome of total humeral endoprosthetic reconstruction. QUESTIONS/PURPOSES: The purposes of this study were (1) to assess the longevity of total humerus prostheses in those patients who survived their disease; (2) to review the complications associated with this prosthesis; and (3) to assess the Musculoskeletal Tumor Society functional score in survivors. METHODS: Thirty-four patients (10 males, 24 females) with a mean age of 26 years (range, 7-86 years) were included in this study. Histological diagnosis was osteosarcoma in 15 patients, chondrosarcoma in seven, Ewing's sarcoma in seven, metastatic carcinoma in three, liposarcoma in one, and giant cell tumor of bone in one remaining patient. Twenty-nine patients had their total humeral endoprosthetic replacement for primary reconstruction, whereas the remaining five patients received their implants for failures with other reconstructive techniques. At a minimum followup of 3 months (mean, 8.2 years; range, 3 months to 29 years), 16 patients were alive with no evidence of disease, whereas 13 of the remaining 18 died with metastatic disease. Local recurrence was seen in five patients and all eventually died of disease progression. RESULTS: According to the Kaplan-Meier survival analysis, the cumulative 10-year implant survival rate was 90%. Periprosthetic infection was seen in four patients, postoperative radial nerve palsy in one, and proximal migration of the prosthesis in three, whereas three patients needed a change of the articular elbow bushings at a mean of 16 years after the implant insertion. The mean Musculoskeletal Tumor Society functional score of the 28 patients who survived their disease for more than 12 months after the index procedure and could therefore be functionally assessed was 83% (range, 60%-93%). CONCLUSIONS: From this small, preliminary report, we suggest that total humeral endoprosthetic replacement may be a reasonable option of reconstruction after tumor resection. We have shown that this prosthesis preserves the function of the hand. The local recurrence rate observed suggests that careful selection of patients is crucial. Infection was our most common surgical complication, but we showed that in those who survived their tumor, this prosthesis offers a method to preserve a functional upper extremity in some patients. Further study with more patients is necessary to confirm the value of this reconstruction method. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Management of pelvic giant cell tumours involving the acetabular bone.

The purpose of this study was to establish the optimal surgical treatment in patients with a Giant Cell Tumour (GCT) involving the acetabular bone. The surgical outcome in 10 patients with GCT involving the acetabular bone was reviewed. Patients were divided into two groups: group 1 in which 5 patients were primarily treated by curettage, and group 2, in which 5 patients were treated by resection and pelvic reconstruction. In group 1, local recurrence occurred in two cases. The functional outcome was excellent or good in 4, and poor in one case. There were no recurrences in group 2, in which the functional outcome was excellent or good in 4 and poor in one patient. The optimal surgical treatment modality should be based upon the tumour extension. Tumours located primarily in the ischiopubic region and not extending proximally beyond the supra-acetabular line can be adequately treated by extended curettage while those with further proximal extension are better treated by en-bloc resection. However, the possible complications of the different methods of pelvic reconstruction should always be considered.

Surgical options and outcomes in bone sarcoma.

Bone sarcomas are challenging to treat. The primary goal of treatment is local control of the disease while, if possible, achieving salvage of the limb and its function. There is no ideal method of reconstruction in limb-salvage surgery but the choice of the method of reconstruction should be individualized based upon many factors including the patient's age, the extent and location of the tumor, the wishes of the patient, and the availability of surgical facilities and expertise, as well as the cost of the procedure. In this review, the authors explore the advantages and disadvantages of the different methods of limb reconstruction. The surgical management of bone sarcomas is a real challenge to the orthopedic surgeon, owing to the diversity of sites in which tumors arise, combined with the extension of the tumor into adjacent soft tissues and their proximity, in many cases, to major neurovascular structures. There have been dramatic improvements in survival for patients with osteosarcoma and Ewing's sarcoma in the past 30 years owing to increasing effectiveness of chemotherapy. This, along with developments in imaging techniques (magnetic resonance imaging in particular) has led to earlier diagnosis and more accurate preoperative staging. Whilst traditional treatment for bone tumors used to be amputation, advances in surgical techniques have made limb-salvage procedures a valid alternative method of treatment to amputation in 80-85% of patients with primary bone sarcomas.