What's new in lung tumor heterogeneity?

The categorization of lung tumors into histologically defined groups and subtypes is based on morphometric criteria, on various degrees of tumoral differentiation and growth patterns. Light microscopic examination of different sections of one and the same tumor reveals in more than 30% of the cases investigated a qualitative and quantitative heterogeneous cell and tumor growth pattern, which is further proved by additional immunohistochemical, electronmicroscopic and DNA-flow cytometry studies. According to observations on the ultrastructural level mixed or combined morphologic features signaling abnormal differentiation patterns in preneoplastic lesions of the bronchial mucosa were visible. So-called amphicrine cells containing mucous vacuoles as well as granules of neurosecretory type were found in basal cell and goblet cell hyperplasia. Squamous-type cells predominate in epidermoid metaplasia and in dysplasia. Cells containing mucous granules or tonofilaments and scant granules of dense core-type suggestive of squamous neurosecretory differentiation were present in all lesions. The ultrastructural features were correlated with the bronchial carcinoma cell heterogeneity and histogenesis.