[Electron microscope study of lung carcinoid]

123 lung carcinoids were studied, 32 of them electron-microscopically. Ultrastructural features were evaluated with the use of multivariate analysis. The most informative ultrastructural features were the following: correlation between differentiated and undifferentiated cells, the number of cytoplasm organoids including endocrine granules, degree of nuclei polymorphism and their size, specialized contacts, mitoses. Up to 18% of carcinoids, on the average, need ultrastructural verification of the anaplasia degree, this percentage increasing to 27.2% in atypical carcinoids. The above ultrastructural criteria allow to specify malignant potential of carcinoids, facilitate differential diagnosis and make their prognosis.