THE SURFACE-STRUCTURE OF THE HUMAN NASAL-MUCOSA .2. METAPLASIA, DYSPLASIA AND CARCINOMA IN NICKEL WORKERS - A CORRELATED STUDY BY SCANNING-TRANSMISSION ELECTRON AND LIGHT-MICROSCOPY

The results of recent histopathologic studies of the nasal mucosa in Ni workers show that, in addition to metaplastic changes, there are frequently dysplastic alterations which are probably preneoplastic lesions. As seen by scanning electron microscopy, metaplasia appears monomorphic; no major qualitative differences exist between Ni workers and age-matched controls, although it tends to be more pronounced in the former group. Dysplasia and carcinoma are characterized by considerable polymorphism in surface features, which make distinction from metaplasia simple. In dysplasia and carcinoma, 4 defined types of surface can be distinguished: globule- and tongue-like structures, pleomorphic microvilli an microridges. Parts of individual cells and adjacent cells often show a considerable variation in surface pattern. The surface structures are dynamic features and changes in these are related to the degree of maturation, genetic and metabolic properties of epithelial cells.