117,603 research outputs found
Fine-Grained Complexity of Earth Mover’s Distance Under Translation
No full textPublisher Copyright: © Karl Bringmann, Frank Staals, Karol Węgrzycki, and Geert van Wordragen.The Earth Mover’s Distance is a popular similarity measure in several branches of computer science. It measures the minimum total edge length of a perfect matching between two point sets. The Earth Mover’s Distance under Translation (EMDuT) is a translation-invariant version thereof. It minimizes the Earth Mover’s Distance over all translations of one point set. For EMDuT in R1, we present an Oe(n2)-time algorithm. We also show that this algorithm is nearly optimal by presenting a matching conditional lower bound based on the Orthogonal Vectors Hypothesis. For EMDuT in Rd, we present an Oe(n2d+2)-time algorithm for the L1 and L∞ metric. We show that this dependence on d is asymptotically tight, as an no(d)-time algorithm for L1 or L∞ would contradict the Exponential Time Hypothesis (ETH). Prior to our work, only approximation algorithms were known for these problems.Peer reviewe
Diffuse-type tenosynovial giant cell tumour: Current treatment concepts and future perspectives
No full textAt present, the optimal treatment strategy in patients with diffuse-type tenosynovial giant cell tumour (D-TGCT) is unclear. The purpose of this review was to describe current treatment options, and to highlight recent developments in the knowledge of the molecular pathogenesis of D-TGCT as well as related therapeutic implications. Epidemiology, clinical features, and the pathogenesis of D-TGCT and the most widely used treatment modalities are described. D-TGCT is a benign clonal neoplastic proliferation arising from the synovium. Patients are often symptomatic and require multiple surgical procedures during their lifetime. Currently, surgery is the main treatment for patients with D-TGCT, with relapse rates ranging from 14% to 55%. Radiosynovectomy and external beam radiotherapy have been used in combination with surgical excision or as single modalities. The finding that D-TGCT cells overexpress colony-stimulating factor 1 (CSF1), resulting in recruitment of CSF1 receptor (CSF1R)-bearing macrophages that are polyclonal and make up the bulk of the tumour, has led to clinical trials with CSF1R inhibitors. These inhibitors include small molecules such as imatinib, nilotinib, PLX3397, and the monoclonal antibody RG7155. In conclusion, D-TGCT impairs patients' quality of life significantly. The evidence that the pathogenetic loop of D-TGCT can be inhibited could potentially change the therapeutic armamentarium for this condition. Clinical trials of agents that target D-TGCT are currently ongoing. In the meantime, international registries should be activated in order to provide useful information on this relatively rare tumour
Chondromas
No full textDefinition: Intramedullary neoplasm made of well-differentiated hyaline cartilage
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Diagnosis and prognosis for the Ewing family of tumors
No full textBackground: Ewing's sarcoma was first described by James Ewing in 1921. It is the second most common bone sarcoma seen in children, adolescents and young adults after osteosarcoma and belongs to the group of 'small round blue cell tumors', showing an aggressive natural history. Once almost invariably fatal and treated only with palliative radiation, thanks to a multidisciplinary approach, the probability of survival at 5years is now - 65 - 75% for patients with localized disease. This percentage is no more than 20 - 25% for patients with metastatic disease at presentation. Objective: To review epidemiology, diagnosis and prognosis of Ewing's sarcoma family tumors (EFT) of bone. This entity includes a wide spectrum of tumors, from the less differentiated or classic Ewing's sarcoma to the more differentiated peripheral neuroectodermal tumor. A translocation involving the EWS gene on the chromosome 22 band q12 is characteristic of EFTs. Conclusion: A complete clinical and radiological assessment is essential for initial patient evaluation. Owing to the rarity of this entity, whenever an EFT is suspected patients should be referred to a bone tumor treatment center before a diagnostic biopsy is performed. The molecular characterization of chromosomal translocations has an important role in the diagnosis of EFT. © 2009 Informa UK Ltd. All rights reserved
Osteochondromas
No full textDefinition: Benign cartilaginous neoplasm arising from the surface of the bone, histologically mimicking abnormal epiphyseal plate which grows and matures according to normal enchondral ossification
Advances in treatment for tenosynovial giant cell tumors
No full textIntroduction: Tenosynovial giant cell tumor (TGCT) is a benign clonal neoplastic proliferation arising from the synovium often causing pain, swelling, joint stiffness, and reduced quality of life. The optimal treatment strategy in patients with diffuse-type TGCT (dt-TGCT) is unclear. The purpose of this review is to describe recent advances in the knowledge of TGCT pathogenesis and potential therapeutic implications. Areas covered: Current treatment options for TGCT are discussed, including surgery and radiotherapy. Recent evidence that TGCT cells overexpress colony-stimulating factor 1 (CSF1), resulting in recruitment of CSF1 receptor (CSF1R) positive tumor-associated macrophage and contributing to tumor growth, has created new opportunities for systemic treatments of dt-TGCT. Results of clinical trials with CSF1R inhibitors are now available. These inhibitors include small molecules such as imatinib, nilotinib, pexidartinib, and monoclonal antibodies like emactuzumab, MCS110, and cabiralzumab. Expert opinion: TGCT impairs patients’ quality of life significantly. The confirmation that the pathogenetic loop of TGCT can be inhibited through targeted agents could potentially change the therapeutic armamentarium for this condition
Dedifferentiated parosteal osteosarcoma: the experience of the Rizzoli Institute
No full textBACKGROUND. Dedifferentiated parosteal osteosarcoma (DPOS) is a variant of osteosarcoma in which a high-grade sarcoma coexists with a conventional parosteal osteosarcoma (c-POS), either at presentation (synchronous type) or at the time of recurrence (metachronous type). Only approximately 60 patients have been reported in the literature. The objective of this study was to analyze the clinicopathologic and radiographic features of a relatively large number of patients with DPOS in an attempt to define further the histologic and biologic behavior of this rare entity. METHODS. In a series of 120 patients with parosteal osteosarcoma who were seen at the Rizzoli Institute from 1958 to 2000, the authors identified 29 patients who were diagnosed with DPOS. The authors reviewed the clinical and radiologic features, histologic sections, treatments, and outcomes in this group of patients with DPOS. RESULTS. Twelve patients were male, and 17 patients were female. The patients ranged in age from 15 years to 65 yrs (average, 36 years; median, 32 years). One tumor involved the scapula, one involved the ilium, and another involved the skull. All 26 of the other tumors were located in the long bones (14 in the femur, 5 in the humerus, 3 in the tibia, 3 in the fibula, and 1 in the ulna). In 18 patients, radiographic areas of lucency were seen within an otherwise sclerotic lesion. Histologically, the dedifferentiated component was high-grade osteoblastic osteosarcoma in 14 patients, fibroblastic osteosarcoma in 10 patients, giant cell-rich osteosarcoma in 3 patients, and chondroblastic osteosarcoma in 2 patients. All tumors were Stage IIB, and invasion of the medullary canal was detected in 19 patients (65%). Twenty-eight patients underwent surgery, and 18 of those patients received chemotherapy (5 patients received neoadjuvant chemotherapy, and 13 patients received adjuvant). Nine patients were dead and 20 patients were alive (average follow-up, 107 months; range, from 3 months to 36 years) at the last follow-up. Of the nine patients who died, one patient received no treatment, five patients underwent surgery (with three patients achieving adequate margins) in combination with chemotherapy, and three patients underwent surgery only (with adequate margins achieved). Of the 20 patients who remained alive, 13 patients underwent surgery (with 10 patients achieving adequate margins) in combination with chemotherapy, whereas 7 patients underwent surgery only (all with adequate margins). Seven of the nine patients who died had widespread metastases. One patient died of causes unrelated to the tumor, and another patient died shortly after undergoing resection of a lesion in the skull. CONCLUSIONS. Dedifferentiation occurred in approximately 24% of patients with c-POS. The prognosis for patients with DPOS was better than the prognosis for patients with dedifferentiated central and dedifferentiated peripheral chondrosarcoma. © 2005 American Cancer Society
Non-surgical treatment of chondrosarcoma: Current concepts and future perspectives
No full textChondrosarcoma represents a heterogeneous group of malignant cartilage tumors. Surgery is the most important component of treatment. Although convincing evidence of its benefit is lacking, chemotherapy might be useful in the treatment of mesenchymal and dedifferentiated chondrosarcoma. Radiotherapy plays an important role in the treatment of chondrosarcomas located in the spheno-occipital region and cervical spine. New modern radiation techniques could further improve the outcome for patients with lesions in sites that are surgically difficult to access. Finally, better understanding of molecular diagnostics and pathogenesis of chondrosarcoma, together with the development of new therapeutic agents, has resulted in numerous studies investigating potentially active treatment approaches to this disease. However, at present, the majority of these new compounds are being tested in preclinical settings, and their future clinical application still needs to be defined. © 2010 Elsevier Inc. All rights reserved
Rare primary malignant bone sarcomas
No full textRare primary malignant bone sarcomas (RPMBS), other than osteosarcoma, chondrosarcoma, chordoma, and Ewing sarcoma, account for about 5-10% of primary bone tumors and represent a major diagnostic challenge. These tumors include spindle cell and round cell sarcoma entities, hemangiopericytoma-like and vascular tumors. Additionally, several histotypes, traditionally described in the soft tissues, such as myxofibrosarcoma, synovial sarcoma, and malignant peripheral nerve sheath tumor of bone, have been reported in patients with primary bone tumors. While wide surgical resection is the mainstay of local treatment, systemic therapy of these rare entities is controversial. Patients with undifferentiated spindle cell or pleomorphic high-grade tumors of bone, are usually treated with osteosarcoma-like chemotherapy, while patients with round cell and undifferentiated round cell tumors (URCTs), may respond to sarcoma treatment regimens for Ewing sarcoma patients. Studies on analogies and differences among these ultra-rare tumors have seldom been reported. This review describes relevance, clinical aspects, diagnostic procedures, staging, treatment recommendations, and current research in this composite tumor group
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