[Application of electron microscopy to tumor diagnosis--observation of 1000 cases with both light and electron...

We observed 1000 cases human tumors by electron microscope, as compared with by light microscope. Results were classified into four groups: First, the diagnosis by both light microscope and electron microscope were the same in 92 per cent of total cases. Second, diagnosis by light microscope was completely changed by the use of electron microscope, and the correct diagnosis was determined only by electron microscope in 4 percent when light microscope failed. Third, although major diagnosis of some tumors by both light and electron microscope was the same, by electron microscope, the diagnosis was extended and supplemented in 3 per cent. Finally, diagnosis was still unclear in 1 per cent. We think that ultrastructural evaluation contributes to diagnosis in 7 per cent of all the cases. Electron microscope plays a very important role in the differential diagnosis of tumors, especially, small cell malignant tumors, and pleomorphic malignant tumors, and also in determination of two-directional or multi-directional differentiation of some tumors.