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Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myositis ossificans traumatica (MOT) is a nonneoplastic, heterotopic ossification of soft tissues i.e. skeletal muscle, tendons, aponeuroses and fascia. It is often encountered in young male athletes participating in contact sports as a result of a single or repeated contusion. MOT tends to be solitary, localized and well circumscribed with a self-limited growth potential that may culminate in regression. The pathogenesis of MOT is still enigmatic. Recent animal experiments have led to a theory that mesenchymal connective tissue cells, undergo metaplasia induced by trauma and probably osteogenic proteins, to fibroblasts and osteoblasts. These cells deposit and structure osteoid centripetally in the lesion. As the lesion matures, cancellous bone develops into mature, lamellar bone in the periphery of the lesion. In its earlier stages MOT is easily cytologically and radiologically confused with osteogenic sarcoma. The management of MOT is largely conservative and the principles are of considerable value to physicians and physiotherapists engaged in the treatment of sports injuries. This article reviews the various forms of myositis ossificans as well as the pathology, diagnosis and treatment options.
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PMID:[Traumatic myositis ossificans. Posttraumatic non-neoplastic heterotopic ossification]. 748 51

We discuss a patient with an occult, densely calcified synovial sarcoma of the hip who came to clinical attention because of pulmonary metastases. When synovial sarcomas present with dense and conglomerate calcification, they may be confused with benign processes such as myositis ossificans or tumoral calcinosis. Malignancies such as extraskeletal osteogenic sarcoma, extraskeletal chondrosarcoma, and mesenchymal chondrosarcoma must also be considered in the differential diagnosis.
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PMID:Case report 878: Densely calcifying synovial sarcoma of the hip metastatic to the lungs. 788 82

Scintigraphy was instrumental in two histologically proven cases of forme fruste melorheostosis. Radionuclide bone scans demonstrated a moderately increased uptake of radiopharmaceutical localized to the "flowing" cortical hyperostosis of melorheostosis observed radiographically. The medullary portion of the affected bones showed no increase in tracer activity. In one case, imaging with Tl-201 chloride demonstrated increased focal activity of the lesion. These scintigraphic findings can help distinguish the mildest manifestation (forme fruste) of melorheostosis from the well-ossified lesions of myositis ossificans and parosteal or periosteal osteosarcoma. The findings of MRI are also described in one patient.
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PMID:Radionuclide imaging in forme fruste of melorheostosis. 806 70

A case of parosteal osteosarcoma is reported. In spite of the pathognomonic plain radiographic signs of parosteal osteosarcoma, it is very uneasy to differentiate it from myositis ossificans circumscripta in the mature stage. CT and MRI defined the extent of the tumor into the soft tissue, the medullary and cortical invasion and gave more information about the composition of the lesion.
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PMID:Parosteal osteosarcoma. 825 57

The benign bone lesions--osteoma, osteoid osteoma, and osteoblastoma--are characterized as bone-forming because tumor cells produce osteoid or mature bone. Osteoma is a slow-growing lesion most commonly seen in the paranasal sinuses and in the calvaria. When it occurs in the long bones, it is invariably juxtacortical and may need to be differentiated from, among others, parosteal osteosarcoma, sessile osteochondroma, and a matured juxtacortical focus of myositis ossificans. Osteoid osteoma and osteoblastoma appear histologically very similar. Their clinical presentations and distribution in the skeleton, however, are distinct: osteoid osteoma is usually accompanied by nocturnal pain promptly relieved by salicylates; osteoblastoma arises predominantly in the axial skeleton, spinal lesions constituting one-third of reported cases. This review focuses on the application of the various imaging modalities in the diagnosis, differential diagnosis, and evaluation of these lesions. Their histopathology also is discussed, and their treatment briefly outlined.
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PMID:Benign bone-forming lesions: osteoma, osteoid osteoma, and osteoblastoma. Clinical, imaging, pathologic, and differential considerations. 827 84

Extraskeletal osseous and cartilaginous tumors and tumorlike conditions of the extremities can often be differentiated radiologically; for those that cannot, knowledge of the spectrum of lesions will allow a suitably ordered differential diagnosis. Of the osseous lesions--myositis ossificans, fibro-osseous pseudotumor, fibrodysplasia ossificans progressiva, soft-tissue osteoma, and extraskeletal osteosarcoma--all but myositis ossificans are relatively rare. Myositis ossificans has a distinct mineralization pattern that can be observed radiologically as a peripheral rim of lamellar bone. Fibro-osseous pseudotumor typically occurs in the digits of the hand and lacks the well-defined zoning pattern of myositis ossificans. The cartilaginous entities include the true tumors, soft-tissue chondroma and extraskeletal chondrosarcoma, and the tumorlike process, synovial osteochondromatosis. The tumors are relatively rare; synovial osteochondromatosis commonly affects middle-aged men, especially in the knee, and is associated with osteoarthritis. The differential diagnosis for these extraskeletal osseous and cartilaginous lesions includes soft-tissue sarcoma, benign mesenchymoma, malignant mesenchymoma (rare), calcified tophi in gout, melorheostosis (rare), pilomatricoma (rare), and tumoral calcinosis (rare).
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PMID:From the archives of the AFIP. Extraskeletal osseous and cartilaginous tumors of the extremities. 835 73

Alterations of tumour suppressor genes are considered crucial steps in the development of human cancers. Expressions of p53 protein, a product of the tumour suppressor gene altered most commonly in human cancers examined so far, were investigated immunohistochemically in 18 osteosarcomas and 40 other malignant and benign lesions of bone. A monoclonal antibody clone PAb240, which recognizes a common conformational epitope of mutant p53 proteins, stained nuclei of tumour cells in 12 of 18 osteosarcomas (67%). Six tumours (33%) particularly showed positive immunoreactions in more than half of the tumour cells. PAb240 also stained tumour cells in a small number of other malignant bone tumours, such as malignant fibrous histiocytoma, chondrosarcoma, and Ewing's sarcomas. Furthermore, a small number of cells of giant-cell tumours were positively stained. In contrast, PAb240 was completely negative in 21 benign bone tumours and reactive lesions examined. Another monoclonal antibody clone PAb1801, which reacts with both wild- and mutant-type p53 protein, reacted in nuclei of tumour cells of 7 osteosarcomas (39%). Most of those also reacted with PAb240. PAb1801 was expressed much more frequently in other malignant bone tumours and giant-cell tumours. In addition, PAb1801 showed intranuclear positive reactions in tumour cells of a benign chondroblastoma, and reactive cells such as actively proliferating preosteoblasts in a myositis ossificans and osteoclast-like giant cells in a giant-cell tumour. The immunoelectron-microscopic observation that p53 protein was localized in euchromatic areas of nuclei of osteosarcoma cells supported the specificity of immunoreaction for p53 protein, indicating an active role of p53 protein in the regulation of DNA synthesis and transcription. These findings suggest that point mutation of the p53 gene is frequently involved in the development of osteosarcomas. PAb240 may be a useful tool not only in screening point mutations of the p53 gene in osteosarcomas but also in the differential diagnosis between osteosarcomas and reactive bone-forming lesions. Expressions of mutant p53 protein were not correlated with any clinical or pathological factors examined, although the results should be confirmed in studies of a large number of osteosarcomas.
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PMID:Analysis of mutant P53 protein in osteosarcomas and other malignant and benign lesions of bone. 841 91

We present the findings on 201Tl and 99mTc-MDP scintigraphy in three patients suffering from heterotopic ossification (two patients presenting with myositis ossificans and one patient presenting with juxta-articular ossification in combination with myositis ossificans). Since resection of the lesions has to be delayed until stabilization, 99mTc-MDP is often used as a parameter of lesional activity, although it is not optimal. For this clinical problem, we evaluated 201Tl scintigraphy as a marker of metabolic activity. In addition to the well-documented uptake of 99mTc-MDP, marked accumulation of 201Tl was observed in all heterotopic ossification sites. Hence, our results support the use of 201Tl scintigraphy in the therapeutic management and monitoring of conditions associated with ectopic ossification. On the other hand, although myositis ossificans is sometimes clinically, radiographically and even histologically confused with extraosseous osteogenic sarcoma, 201Tl accumulation may not be a helpful factor in the differential diagnosis due to the presence of tracer accumulation in both disorders.
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PMID:Thallium-201 accumulation in myositis ossificans and in juxta-articular ossification. 852 12

Non-traumatic localized myositis ossificans is a rare variant of pseudotumoral muscular ossification. In the early stage it may be misdiagnosed as soft tissue sarcoma or some kind of osteosarcoma. Myositis ossificans itself does not always require therapy; when diagnosed on the basis of the typical features revealed by meticulous non-invasive investigation, biopsy is not mandatory for confirmation of the diagnosis. The diagnostic procedures needed - radiography, ultrasound, MRI, and isotope bone scan - are discussed with reference to three clinical case reports.
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PMID:[Diagnosis and spontaneous course of non-traumatic localized myositis ossificans]. 856 Feb 76

Bone tumors represent a group of tumors of various dignity. In spite of this single tumor entities may display strong morphological resemblance to each other which can in turn result in profound difficulties in differential diagnosis. The biological behaviour of a tumor is mainly determined by its rate of proliferation. In this study the rate of proliferation of 64 bone tumors (30 high-grade central osteosarcomas, 6 low-grade osteosarcomas, 8 giant cell tumors, 8 aneurysmatic bone cysts, 5 osteoidosteomas/osteoblastomas, 7 fibrous dysplasias and 5 cases of a myositis ossificans) were analysed. Immunohistochemistry was performed on paraffin-embedded tissue sections using the MIB-1 monoclonal antibody. MIB-1 recognizes the proliferation-associated Ki-67 protein which is expressed during the active phases of the cell cycle but cannot be detected in senescent cells. Among high-grade central osteosarcomas a significantly higher rate of proliferation (average value 30%) was found in comparison with low-grade osteosarcomas and other benign intraosseous bone tumors. This approach proved to be very useful in the distinction between high-grade and low-grade osteosarcomas as well as bone-forming intraosseous tumors. However distinguishing low-grade osteosarcomas from benign bone tumors by determining only the rate of proliferation was not possible, although interestingly, the proliferative rate of myositis ossificans, a purely reactive lesion, was in the range of the values determined for high-grade osteosarcoma.
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PMID:[Cell proliferation in bone tumors. Immunohistologic study of Ki-67 protein expression]. 868 97


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