[Results of the electron microscopic diagnosis of human tumors (an analysis of 1000 cases)].

A review of electron-microscopic diagnostic investigations made on biopsy specimens from 1000 patients showed the range of tumors requiring ultrastructural diagnosis to be fairly broad, encompassing virtually all major tumor sources including soft tissues (37% of the cases), epithelium (31.8%), hematopoietic organs (21.3%), pigment-forming tissues (4.9%), and bones (3.3%). The tissue and cellular origin of the tumor was identified, i.e. a differential diagnosis was correctly made and/or the histogenetic (cytogenetic) type of the tumor was established, in most (83.0%) of the cases, whereas the organ of tumor origin was identified in only 6.0%. Electron-microscopically, the histological diagnosis was confirmed in 45.3% of the cases, made more precise in 19.0%, and discarded in 5.1%; in 5.8%, electron microscopy confirmed as correct one of the diagnoses presumed on histologic grounds, while in 3.9% the diagnosis could not be verified because the tumors consisted of undifferentiated cells in their entirety. Historic material (formalin-fixed or from paraffin blocks) and stained histologic sections were used for the ultrastructural diagnoses.