Ewing sarcoma is the second most common bone sarcoma in children after osteosarcoma. It is a very aggressive malignancy for which systemic treatment has greatly improved outcome for patients with localized disease, who now see survival rates of over 70%. However, for the quarter of patients presenting with metastatic disease, survival is still dismal with less than 30% of patients surviving past 5 years. Patients with disease relapse, local or distant, face an even poorer prognosis with an event-free 5-year survival rate of only 10%. Unfortunately, Ewing sarcoma patients have not yet seen the benefit of recent years’ technical achievements such as next-generation sequencing, which have enabled researchers to study biological systems at a level never seen before. In spite of large multinational studies, treatment of Ewing sarcoma relies entirely on chemotherapeutic agents that have been largely unchanged for decades. As many promising modern therapies, including monoclonal antibodies, small molecules, and immunotherapy, have been disappointing to date, there is no clear candidate as to which drug should be investigated in the next large-scale clinical trial. However, the mechanisms driving tumor development in Ewing sarcoma are slowly unfolding. New entities of Ewing-like tumors, with fusion transcripts that are related to the oncogenic EWSR1-FLI1 fusion seen in the majority of Ewing tumors, are being mapped. These tumors, although sharing much of the same morphologic features as classic Ewing sarcoma, behave differently and may require a different treatment. There are also controversies regarding local treatment of Ewing sarcoma. The radiosensitive nature of the disease and the tendency for Ewing sarcoma to arise in the axial skeleton make local treatment very challenging. Surgical treatment and radiotherapy have their pros and cons, which may give rise to different treatment strategies in different centers around the world. This review article discusses some of these controversies and reproduces the highlights from recent publications with regard to diagnostics, systemic treatment, and surgical treatment of Ewing sarcoma.

Aneurysmal bone cysts are benign bone tumors that usually present in childhood and early adulthood. They usually manifest as expansile osteolytic lesions with a varying potential to be locally aggressive. Since their first description in 1942, a variety of treatment methods has been proposed. Traditionally, these tumors were treated with open surgery. Either intralesional surgical procedures or en bloc excisions have been described. Furthermore, a variety of chemical or physical adjuvants has been utilized in order to reduce the risk for local recurrence after excision. Currently, there is a shift to more minimally invasive procedures in order to avoid the complications of open surgical excision. Good results have been reported during percutaneous surgery, or the use of embolization. Recently, sclerotherapy has emerged as a promising treatment, showing effective consolidation of the lesions and functional results that appear to be superior to the ones of open surgery. Lastly, non-invasive treatment, such as pharmaceutical intervention with denosumab or bisphosphonates has been reported to be effective in the management of the disease. Radiotherapy has also been shown to confer good local control, either alone or in conjunction to other treatment modalities, but is associated with serious adverse effects. Here, we review the current literature on the methods of treatment of aneurysmal bone cysts. The indication for each type of treatment along reported outcome of the intervention, as well as potential complications are systematically presented. Our review aims to increase awareness of the different treatment modalities and facilitate decision-making regarding each individual patient.

In the case of primary malignant tumors, extensive metastatic disease, major trauma or end-stage revision arthroplasty, the orthopaedic surgeon often has to deal with the need to reconstruct large skeletal defects, or replace bone of low quality. In the past years this was frequently impossible, and the only solution was amputation of the extremity. Later, the introduction of custom-made endoprostheses capable of reconstructing large skeletal defects, also known as megaprostheses, allowed for sparing of the extremity. This was especially valuable in the case of oncologic orthopaedic surgery, as advances in the medical treatment of sarcoma patients improved prognosis and limb-preserving surgery proved to have comparable patient survival rates to amputation. However, custom-made designs were implicated in frequent mechanical failures. Furthermore, they were extremely difficult to revise.The introduction of modular endoprostheses in the 1980s marked a new era in orthopaedic oncologic surgery. Modular megaprostheses consist of a number of different components in readily available sets, which can be assembled in various combinations to best address the specific bone defect. Moreover, they proved to have considerably lower rate of mechanical failures, which were also much easier to address during revision surgery by replacing only the parts that failed. The functional outcome after reconstruction with megasprostheses is often very satisfactory and the patient can enjoy a good quality of life. Nowadays, the major challenge is to eliminate the rate of non-mechanical complications associated with surgery of that magnitude, namely the risk for wound dehiscence and necrosis, deep infection, as well as local recurrence of the tumor.In our present mini-review, we attempt to make a critical approach of the available literature, focusing on the multiple aspects of reconstructive surgery using megaprostheses. We present the evolution of megasprosthetic implants, the indications for their use, and describe the outcome of surgery, so that the non-specialized orthopedic surgeon also becomes familiar with that kind of surgery which is usually performed in tertiary centers. A special interest lays in the recent developments that promise for even better results and fewer complications.

Treatment of Ewing sarcoma of the pelvic bones remains one of the most difficult tasks in the treatment of bone sarcomas. Whether surgery or radiation therapy is the best local treatment is still a matter of debate. The aim of the present study was to compare sacral and nonsacral sites with regard to the treatment and outcome of pelvic Ewing sarcomas. Patients with Ewing sarcoma of the osseous pelvis diagnosed between 1986 and 2011 were identified through the Scandinavian Sarcoma Group registry. Data regarding tumor size, local treatment (surgery or radiation therapy), metastatic disease, surgical margins, local recurrence, and overall survival were analyzed. Of the 117 patients examined, eighty-eight had tumors in the innominate bones and twenty-nine, in the sacrum. Radiation therapy was the sole local treatment for 40% of the innominate bone tumors in contrast to 79% of the sacral tumors. The five-year disease-free survival rate in the latter group (66%) was greater than that in the group with tumors in the innominate bones (40%) (p = 0.02 adjusted for size). Disease-free survival among patients with Ewing sarcoma was improved when the tumor was localized in the sacrum compared with the innominate bones, where these tumors are generally larger. Local radiation therapy alone appears to result in good local tumor control and may be the treatment of choice for sacral tumors. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Purpose of Review This review presents a selection of regulatory molecules of tumor microenvironmental properties and metastasis. Signaling pathways controlling mesenchymal biology in bone and soft-tissue sarcomas found in children and adolescents are prioritized. Recent Findings The tumor microenvironment of pediatric tumors is still relatively unexplored. Highlighted findings are mainly on deregulated genes associated with cell adhesion, migration, and tumor cell dissemination. How these processes are involved in a mesenchymal phenotype and metastasis is further discussed in relation to the epithelial to mesenchymal transition (EMT) in epithelial tumors. Cell plasticity is emerging as a concept with impact on tumor behavior. Summary Sarcomas belong to a heterogeneous group of tumors where local recurrence and tumor spread pose major challenges despite intense multimodal treatments. Molecular pathways involved in the metastatic process are currently being characterized, and tumor-regulatory properties of structural components, and infiltrating, non-malignant cell types should be further investigated.

Aims: The aim of this study was to identify factors that determine outcomes of treatment for patients with chondroblastic osteosarcomas (COS) of the limbs and pelvis. Patients and Methods: The authors carried out a retrospective review of prospectively collected data from 256 patients diagnosed between 1979 and 2015. Of the 256 patients diagnosed with COS of the pelvis and the limbs, 147 patients (57%) were male and 109 patients (43%) were female. The mean age at presentation was 20 years (0 to 90). Results: In all, 82% of the patients had a poor response to chemotherapy, which was associated with the presence of a predominantly chondroblastic component (more than 50% of tumour volume). The incidence of local recurrence was 15%. Synchronous or metachronous metastasis was diagnosed in 60% of patients. Overall survival was 51% and 42% after five and ten years, respectively. Limb localization and wide surgical margins were associated with a lower risk of local recurrence after multivariable analysis, while the response to chemotherapy was not. Local recurrence, advanced patient age, pelvic tumours, and large volume negatively influenced survival. Resection of pulmonary metastases was associated with a survival benefit in the limited number of patients in whom this was undertaken. Conclusion: COS demonstrates a poor response to chemotherapy and a high incidence of metastases. Wide resection is associated with improved local control and overall survival, while excision of pulmonary metastases is associated with improved survival in selected patients. Cite this article: Bone Joint J 2019;101-B:739–744.