[Ultrastructural evaluation of pulmonary adenocarcinoma. I. Cytologically homogeneous phenotypes].

A group of 102 lung carcinomas with an ultrastructural evidence of exocrine features comprised 88 adenocarcinomas and 2 adenosquamous carcinomas classified correctly according to the WHO histological typing as well as 12 other carcinomas which had to be re-classified after electron microscopy. Microvilli and secretory granules served as exocrine markers. The microvilli were more specific than granules because of being missing in 15 less differentiated tumours and granules in 45 cases. Microvilli were oriented into intercellular lumina in 65 tumours as well as into intracellular secretion slots in 16 cases, nonpolarized microvilli encirced the circumference of less differentiated cells in 22 tumours. Glycocalyceal bodies were identified not rarely and that was why they did not prove useful in distinguishing primary and secondary lung adenocarcinomas. Electron microscopical classification of adenocarcinomas, more reliable than the light microscopical one, was based on a phenotypical expression of various secretion granules in tumour cells. Phenotypical homogeneity characterized only 56 percent of tumours (57). The two most frequent phenotypes were together mucous cells (5) and dense granule microvillous elements (9) representing serous cells of bronchial glands; cells with apical dense granules but without microvilli (7) represented Clara cells in peripheral carcinomas; type II pneumocytes oftener were normal cells included in tumours (8) than proper tumour cells (2).