How does Japan differentiate hyperplasia from neoplasia?

A Japanese pathologist's contribution to the discussion of the problem on differentiation of hyperplasia from neoplasia is to introduce his experience and knowledge in human and experimental pathology of gastric, hepatic, and uterine cervical cancers, all of which are prevalent in Japan. Canine and rodent gastric cancers induced experimentally by N-ethyl-N'-nitro-N-nitrosoguanidine or N-methyl-N'-nitro-N-nitrosoguanidine, respectively, show different histologic types which are similar to human gastric cancer when examined routinely by endoscopic method. Dogs show more similarities to human gastric cancer than rats in the morphologic features and responses to chemotherapy. Serial liver biopsies performed on patients with liver diseases revealed the final stages of liver cell carcinoma in some of them. They all progressed to liver cirrhosis before terminating in carcinoma. However, this does not mean that the hyperplastic nodule is an obligatory precursor of carcinoma in human. Among experimental models of liver cancer produced by a large number of agents, only carbon tetrachloride and luteoskyrin seem to induce liver cell carcinoma combined with cirrhotic lesions in rodents. The mode of manifestation of atypical changes in the proliferating cells as preneoplastic or neoplastic lesions seems to differ according to tissue. The cellular pathology of cervicovaginal smears is a reliable index for detection of carcinoma in the cervix, where the appearance of atypical cells represents a landmark between benign and malignant tumors.