Electron Microscopy in Diagnostic Pathology with Reference to Mesenchymal Tumors

The experience acquired over a period of 15 years of diagnostic electron microscopy of fine needle aspirates and surgical specimens constitutes the base for this thesis. Some of the tumors analyzed represent rare soft tissue tumors, and consequently not very often ultrastructurally described. In locations where sarcomas are rare and unexpected, electron microscopy may contribute to a correct tumor classification when type specific structures are present. Electron microscopic examination is a suitable method to confirm presence of mesenchymal tumor cells in cultures and to compare the morphology in cultures and fresh tumor tissue provided that the ultrastructural features are specific for the tumor in question. Fine needle aspiration together with the use of electron microscopy is a reliable combination in the typediagnosis of small round cell malignant tumors of childhood and adolescence and spindle cell tumors as peripheral nerve sheath tumors, leiomyosarcoma and synovial sarcoma, especially of the monophasic variant. Electron microscopy contributes to the understanding of successive morphologic changes in the dermal microvasculature of Kaposi´s sarcoma. This thesis presents examples that highlight the value of electron microscopy in the multidisciplinary management of musculoskeletal tumors