29 research outputs found
A call for transparent reporting to optimize the predictive value of preclinical research
The US National Institute of Neurological Disorders and Stroke convened major stakeholders in June 2012 to discuss how to improve the methodological reporting of animal studies in grant applications and publications. The main workshop recommendation is that at a minimum studies should report on sample-size estimation, whether and how animals were randomized, whether investigators were blind to the treatment, and the handling of data. We recognize that achieving a meaningful improvement in the quality of reporting will require a concerted effort by investigators, reviewers, funding agencies and journal editors. Requiring better reporting of animal studies will raise awareness of the importance of rigorous study design to accelerate scientific progress
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The ultrastructure of small-cell osteosarcoma, with a review of the light microscopy and differential diagnosis
Small-cell osteosarcoma is a rare form of osteosarcoma and often poses difficulty in differential diagnosis when tissue samples do not include any diagnostic osteoid. By light microscopy, it may be difficult to distinguish small-cell osteosarcoma from other small-cell neoplasms, especially Ewing's sarcoma and mesenchymal chondrosarcoma. Relatively little has been reported about the ultrastructural characteristics of small-cell osteosarcoma, whereas electron microscopic examination has proven very useful in the diagnosis of most other small-cell neoplasms. We have studied four proven small-cell osteosarcomas in detail at the electron microscopic level and found their common features to be a high nucleocytoplasmic ratio, poorly differentiated cytoplasm, numerous free ribosomes and mitochondria as the next most prevalent organelle, small junctions, and envelopment of individual and groups of cells by matrix. Beyond these characteristics, cytoplasmic organelles and nuclear features varied, and no single pathognomonic ultrastructural picture was observed. However, within the range of possible ultrastructure of small-cell osteosarcoma, most small-cell neoplasms can be ruled out. Only certain examples of Ewing's sarcoma and mesenchymal chondrosarcoma may be indistinguishable from it when osteoid is not present in the sample
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Angiomyofibroblastoma of the Vulva with Sarcomatous Transformation ("Angiomyofibrosarcoma")
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Expression of epithelial markers in malignant fibrous histiocytoma of the musculoskeletal system: An immunohistochemical and electron microscopic study
We performed an immunohistochemical and ultrastructural study on 67 specimens of malignant fibrous histiocytoma (MFH) from 65 patients. Most of the tumors were musculoskeletal in origin and all presented clinically as a primary malignancy. The tumors were high grade and 57 of 67 were the storiform-pleomorphic subtype. Immunohistochemical studies were performed in 34 cases with both fresh-frozen and formalin-fixed tissue; in 33 cases only formalin-fixed tissue was available. The immunohistochemical panel included vimentin, various molecular weight keratins, epithelial membrane antigen (EMA), desmin, α-1-antitrypsin, and α-1-antichymotrypsin. Seventeen of 67 (25.4%) cases stained with one or more keratin antibodies. The low molecular weight cytokeratins demonstrated the most widespread and intense staining and, using fresh-frozen tissue, increased sensitivity. Epithelial membrane antigen was detected in 20.6% of cases and six of these cases also stained with keratin. The EMA staining was more focal and less intense than the keratin reactivity. The keratin- or EMA-positive cases were not distinguished by their light microscopic or ultrastructural features. Desmin staining was focally present in 16.9% of cases. The vast majority of tumors stained with vimentin and α-1-antitrypsin or α-1-antichymotrypsin. There was no staining of tumor cells for S-100. Appropriately fixed tissue was available for electron microscopic evaluation in 15 of 23 MFHs that stained with keratin or EMA. Ultrastructurally, all tumors were composed of an admixture of cells that had the features of fibroblasts, myofibroblasts, and histiocytes; no epithelial structures were identified. This study confirms that MFH may express epithelial markers. It emphasizes the importance of using electron microscopy and clinical findings to distinguish keratin or EMA-positive MFH from carcinoma. This distinction is important because of the significant differences in therapy and prognosis
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Glial fibrillary acidic protein and keratin expression by benign and malignant nerve sheath tumors
Formalin-fixed, paraffin-embedded sections of 59 ultrastructurally confirmed nerve sheath tumors (NSTs) that included 27 benign schwannomas, five neurofibromas, and 27 malignant schwannomas were studied by the avidin-biotin-peroxidase complex method using antibodies directed against glial fibrillary acidic protein (GFAP), keratin, S-100 protein, vimentin, and desmin. GFAP was expressed by 33% of the benign schwannomas, 40% of the neurofibromas, and 7% of the malignant schwannomas. Keratin was expressed by 7% of the benign schwannomas and 4% of the malignant schwannomas. S-100 protein was expressed by 100% of the benign NSTs and by 40% of the malignant schwannomas. Vimentin was observed in 100% of the benign NSTs and in 85% of the malignant schwannomas. None of the cases stained for desmin. GFAP and cytokeratin expression could not be predicted on the basis of tumor light microscopy or ultrastructure. These findings are of practical importance in routine surgical pathology, particularly with respect to the differential diagnosis of gliomas located in the central nervous system and in immunohistochemical studies of peripherally located, poorly differentiated neoplasms
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Rhabdomyosarcoma of the Long Bone in an Adult A Case Report and Literature Review
Rhabdomyosarcoma is one of the most common sarcomas of childhood. It usually arises in the soft tissues but may involve bone by several different mechanisms, includ ing direct extension, metastatic spread, as a component of dedifferentiated chondrosar coma or malignant mesenchymoma, or as a primary tumor. Only nine cases of primary rhabdomyosarcoma of bone have been previously reported, many of them not well documented. The histologic, immunohistochemical, and ultrastructural findings of a primary rhabdomyosarcoma of the femur in a 68-year-old woman are presented. Also discussed are the different aspects of skeletal muscle differentiation in bone tumors and the possible explanation for the rarity of primary skeletal rhabdomyosarcoma. Int J Surg Pathol 1(4):253-260, 199