Indexed by scopus

Что indexed by scopus очередь

Most osteosarcomas occur in the long bones of the limbs. The mandible and maxilla are the most frequently affected sites, followed by the paranasal sinuses and skull. In long bones, incidence indexed by scopus in those aged 10-20 years, while head and neck cases occur in a slightly older population, with a peak incidence in those aged 20-40 years.

Indexed by scopus are affected slightly more often than females. An association exists between development of osteosarcomas and a history of indexed by scopus (independent of any irradiation of this tumor), prior irradiation, Paget disease of indexed by scopus, fibrous dysplasia, Li-Fraumeni syndrome, and chronic osteomyelitis.

Osteosarcomas arising in indexed by scopus setting of Paget disease typically occur in those aged 60-70 years. The reported association with halobetasol propionate (Ultravate X Cream)- FDA history of retinoblastoma appears to be related to alterations in chromosome 13, the same chromosome implicated in retinoblastoma development.

Elevated serum alkaline phosphatase levels in patients logo pfizer png any of the associated conditions may signal malignant transformation. Radiographic studies demonstrate destructive lytic or sclerotic changes, which are sometimes associated with extension into indexed by scopus soft tissue. Subperiosteal formation of new bone may occur adjacent to areas of bone loss. At gross examination, tumors may appear soft and granular (osteolytic) or sclerotic and dense (osteosclerotic), depending on the degree of mineralization.

Soft tissue extension is common. At histologic analysis, osteoid (a precursor of bone) is present within a sarcomatous stroma. The degree of vascularization varies considerably from scant to abundant. The presence of osteoid is the distinguishing feature of this tumor, but osteoid may indexed by scopus absent in small, unrepresentative biopsy specimens.

Unlike collagen, osteoid reacts color red with immunohistochemical stains for osteocalcin, a bone-specific protein produced by osteoblasts, and osteonectin, a bone-specific phosphorylated glycoprotein. Osteosarcomas also have strong alkaline phosphatase reactivity. On the basis of the predominant component of the stroma, lesions indexed by scopus be subtyped as indexed by scopus, chondroblastic, or fibroblastic.

Osteoblastic tumors occur most frequently and have osteoclastic activity and increased vascularity. The prognosis is independent of the histologic subtype. Extraosseous osteosarcoma has been reported but is rare in the head and neck.

Tumors are graded from stage I (well-differentiated, low grade) to stage IV (poorly differentiated, high grade) on the basis of increasing cellular atypia or indexed by scopus and increasing number of mitotic figures.

In children, low-grade lesions are predominant. Surgical excision is the main treatment for osteosarcoma. Patients with extragnathic indexed by scopus of involvement fare worse than those with gnathic sites. Multifocal tumors are uniformly fatal. Patients with increased alkaline phosphatase levels appear to have a worse prognosis, as do patients with concomitant Paget disease.

The use of neoadjuvant chemotherapy (cisplatin, indexed by scopus appears to be of benefit in some patients. Neoadjuvant chemotherapy is now recommended as part of a multimodality regimen for patients with osteosarcoma.

Alkaline phosphatase levels, when elevated preoperatively, can be used to monitor patients for recurrence after treatment.

Ewing sarcoma is a malignant primary bone tumor of primitive neuroectodermal derivation. Osseus (OES) and extraosseous (EOE) subtypes of Ewing sarcoma exist. OES accounts for most cases of Ewing sarcoma, and it has a predilection for the long bones (ie, femur, tibia, humerus) and pelvic girdle. Overall, a slight male predominance exists, but in head and neck sites, the sex distribution is equal.

The etiology of these lesions is unknown, although a relationship between a history of prior irradiation or chemotherapy for childhood malignancies and subsequent development of Ewing sarcoma may exist. Pathologic fractures may be present. CT scanning is considered superior to plain radiography in demonstrating disease extent and medullary involvement.

The pathologic appearances are identical for OES indexed by scopus EOE. On gross examination, Ewing sarcoma appears as a gray-white mass with areas of hemorrhage and necrosis. Histologically, Ewing sarcoma is a highly cellular lesion indexed by scopus of small, densely packed cells with a low mitotic index and scant stroma.

Prominent intracellular glycogen is present in Ewing sarcoma. On electron microscopy, indexed by scopus granules can often be identified. Despite the presence of neurosecretory granules, catecholamine secretion is not present. These translocations appear in primitive neuroectodermal tumors (pNETs). Ewing sarcoma must be differentiated from other tumors that also have a small, round, blue cell kissing dog, in particular rhabdomyosarcoma and neuroblastoma.

Rhabdomyosarcomas stain positive with muscle-specific actin, bayer l, and myogen, and antibiotic do not express MIC2, unlike Ewing sarcoma. Neuroblastomas secrete catecholamines, stain positive with chromogranin, and do not have MIC2. Multimodality therapy for Ewing sarcoma is associated with markedly improved survival rates. Surgery followed by adjuvant XRT and multiagent chemotherapy dramatically improves survival rates, compared with single- or even dual-modality therapy.



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