Atypical Mitosis in Gastric Intestinal Metaplasia in Japanese Patients

The characteristics of the mitotic figures occurring in intestinal metaplasia of the gastric mucosa were investigated in 50 consecutive gastrectomy specimens. The specimens contained, in addition, early gastric cancer of intestinal type (n = 38) or of diffuse type (n = 12). One hundred or more consecutive mitoses/specimen were studied by high‐power microscopy (× 1000). Of the 5,140 mitoses, 1,030 (i.e. 20.0%, range 8–34%) were considered as atypical according to a previous classification. The presence of atypical mitosis was not influenced by the gender or age of the patient, or the histological type of the tumor present in the specimen. Studies of gastrectomy specimens from Swedish patients with early gastric cancer showed a much lower frequency of mitotic figures/specimen and occasional atypical mitosis. The high frequency of atypical mitosis in intestinal metaplasia in the gastric mucosa of Japanese nationals may mirror a profound genetic instability in that mucosa, and suggests that intestinal metaplasia with atypical mitosis may be a precancerous lesion in the Japanese.