A Novel Method for Detecting Single Glandular Intestinal Metaplasia in the Mucosal Surface of the Fixed Stomach Using Methylene Blue

Abstract

A close association between intestinal metaplasia of the stomach and the well-differentiated type of gastric cancer is well recognized. The etiological relationship and how intestinal metaplasia contributes to gastric carcinogenesis are, however, still unclear. In order to answer this question, precise mapping and identification of the smallest lesion of intestinal metaplasia are desired. Establishment of an accurate and easy method for detecting intestinal metaplasia was the goal of this study. Surgical specimens of stomachs resected for gastric cancer were used. The specimens were stained with methylene blue, an oxidation-reduction marker, in whole mount, after fixation with 4% paraformaldehyde in 0.1 M phosphate buffer (pH 7.4), and observed under a stereomicroscope. Normal gastric mucosa was stained blue, whereas intestinal metaplasia mucosa was not stained and had white or sky-blue island-like features. Intestinal metaplasia of complete type was unstained and showed white island-like features, while intestinal metaplasia of incomplete type showed sky-blue staining. With this method, we were able to detect even intestinal metaplasia composed of a single gland, when the intestinal metaplasia was of complete type. When stomach samples were stained in the presence of diphenyleneiodonium chloride (DPI), an inhibitor of nicotineamide adenine dinucleotide phosphate reduced form (NADPH) reductase, all the samples were homogeneously stained blue. Loss of the color of methylene blue was caused by the reductase activity of NADPH reductase, which is strongly and specifically expressed in intestinal metaplasia. A novel method for detecting intestinal metaplasia, even a single gland, was established. Key words:Intestinal metaplasia -Methylene blue -NADPH diaphorase -Cytochrome P-450 reductase -Gastric cancer Intestinal metaplasia in the stomach is one of the most commonest forms of metaplasia in humans.1) An association between intestinal metaplasia and intestinal-type gastric cancer has been reported both epidemiologically and histologically.2-7) There are three possible explanations for this 2, 3) :(1) intestinal metaplasia is a direct precursor lesion of the cancer; (2) intestinal metaplasia creates a favorable milieu for carcinogenesis, perhaps by raising the pH of gastric juice, and improving the growth conditions for bacteria that produce carcinogens; or (3) intestinal metaplasia may simply be a paraneoplastic lesion caused by the same agents that gave rise to the cancer.2) We previously reported that almost all intestinal metaplastic mucosa detected by the Tes-tape method, 8) in samples of φ3 mm in diameter, contains intestinal metaplastic glands of polyclonal origin.9) This finding favors the hypothesis that intestinal metaplasia is not a monoclonally expanding direct precursor of intestinal-type gastric cancer.Intestinal metaplasia can be classifed histologically into two or three types: a complete type (Type I) and an incomplete type (Type II). 4-7, 10, 11) The latter is classified into 2 subtypes (Type IIa an...

Endoscopic diagnosis of gastric mucosal atrophy: Multicenter prospective study

“…The extension of gastric atrophy spreads multifocally from the transitional zone, as described in the Updated Sydney System . Therefore, sampling error could occur in histology of biopsied specimens.…”