[Ultrastructure of carcinoid of the lung].

The paper deals with the electron microscopic analysis of samples of 40 lung tumors histologically diagnosed as carcinoid or malignant carcinoid. The study group was shown to include tumors differing in cell ultrastructure and histological patterns. Three basic tissue patterns formed by 3 specific cellular types were identified: epithelioid, sarcomatoid and symplastic one. Tumors usually showed a combination of the said types with the predominance of one of them. Tumors exhibiting only one morphologic pattern of neurosecretory granules were much more rare. All the neoplasms studied were of neuroendocrine nature.