Diagnosis of minute cancers by the endoscopic Congo red--methylene blue test.

The clinicopathological features of minute cancers of the stomach were investigated, and the accuracy of diagnosis of minute cancers by routine endoscopic examinations and by the endoscopic Congo red - methylene blue test were compared. From 1959 to 1979, 56 minute cancer were found in 54 patients. Minute cancers are defined as those of less than 5 mm in the longest diameter. None involved the muscularis propria, but when minute cancers, especially the depressed type, were more than 4 mm in diameter, cancer cells were frequently found to invade the submucosa. Therefore, minute cancers must be diagnosed as early as possible. A correct diagnosis of minute cancers was made in only 25.0% of the cases by routine endoscopic examinations. But with the Congo red--methylene blue test the diagnostic rate was raised significantly to 75.0%. In this test, tumors are seen as areas in which the dyes become bleached to white, in sharp contrast to the unaffected mucosa. This test is more accurate than other methods for diagnosis of minute cancers, because the target area can be biopsied with greater accuracy.