The ultrastructural heterogeneity of potentially preneoplastic lesions in the human bronchial mucosa

170 consecutive biopsies from the bronchial tree were subjected to ultrastructural analysis. 62 were identified as preneoplastic lesions: of these, 7 as goblet cell hyperplasia, 20 as basal cell hyperplasia, 17 as combined goblet and basal cell hyperplasia, 10 as epidermoid metaplasia, and 8 as dysplasia. The ultrastructural features of these lesions are described. According to these results, preneoplastic lesions of the human bronchial mucosa are composed of heterogeneous populations that display mixed or combined morphologic features signaling abnormal differentiation patterns at this stage. The findings are tentatively correlated with bronchial carcinoma cell heterogeneity and histogenesis.