Histological and autoradiographic study on development of group III lesion (dysplasia grade III) in the stomach

In order to elucidate the biological behaviour of the Group III lesion of the stomach, morphogenesis of the lesion was studied from cell kinetic point of view. In most Group III lesions, the proliferative cell zones were found at the upper third level of the mucosa, whereas they were confined to the middle third and to the lower third level in the normal pyloric and in the intestinalized mucosa, respectively. The smallest Group III lesion was a single gland dysplasia, in which the Group III cells were confined to the middle level of the mucosa. These findings suggested that the Group III lesion must be a change initiated in the neck stem cells of the pyloric mucosa as is the case in the intestinal metaplasia. The Group III cells arising at the neck region surge upwards and then accumulate in the upper part of the foveola to form an aberrant proliferative focus from which a lesion develops by budding. This morphogenesis manifests an adenomatous nature of the lesion. However, there was apparently a spectrum of cytological and histological abnormalities which varied from the lesions which might be considered to be a kind of intestinalized tubule, to the typical Group III lesion. Some Group III lesions imitating the intestinal metaplasia contained the proliferative cell zones at the middle level of the mucosa, indicating that a group of the dysplastic tubules arose zonally, not from a single gland. This morphogenesis reflects a metaplastic nature of the lesion. (ABSTRACT TRUNCATED AT 250 WORDS)