What dye-spraying technique should be chosen in cylindric mucosa?
H.J. Dittler, W.K.H. Kauer (Munich)
The incidence of adenocarcinoma is increasing faster than any other cancer in the United States or Western Europe [1, 2]. Adenocarcinoma is most common in white males with a male to female ratio of 5:1. The disease becomes more common after the age of 40. In Caucasians the incidence of esophageal adenocarcinoma rose 74% between 1973 and 1982 .
Barrett's esophagus (BE) is a condition in which normal squamous epithelium is replaced by metaplastic columnar epithelium . Proper recognition of patients with BE at endoscopy is imperative because of the malignant potential of Barrett's epithelium, which is thought to proceed through a metaplasia-dysplasia-carcinoma sequence . Short segments of Barrett's epithelium have also been demonstrated in association with many gastroesophageal junction adenocarcinomas .
Columnar epithelium in the esophagus has a characteristic red color and velvet-like texture that contrasts sharply with the pale, glossy appearance of adjacent squamous epithelium . Although endoscopic examination can usually distinguish columnar from squamous epithelium in the esophagus, the differentiation between specialized columnar epithelium and gastric columnar epithelium can be made only by histological examination of biopsies.
Different staining techniques are available for squamous epithelium in the esophagus or columnar epithelium in the stomach. Vital staining at endoscopy with Lugol's solution has been advocated to better delineate subtle mucosal changes in squamous cells of the esophagus. Normal epithelium with its relatively high glycogen content stains brown, while dysplastic changes or cancer of the squamous epithelium remain unstained [8, 9].
Toluidine blue staining has also been used to better define subtle changes in the mucosal surface of squamous epithelium . An endoscopic dying method with methylene blue solution has been described as accurate and safe for diagnosing cancer and intestinal metaplasia in the stomach . Introduction of methylene blue into the stomach selectively dyed cancer and intestinal metaplasia dark blue, while normal gastric mucosa, the margin and scar of gastric ulcer, erosions, benign polyp and gastritis without intestinal metaplasia remained undyed.
In a recent report by Canto et al. this technique was adopted for detecting intestinal metaplasia and dysplasia in BE. In an ongoing prospective controlled study, she compared the diagnostic yield of endoscopic surveillance using methylene blue directed biopsies with 4-quadrant random biopsies. Methylene blue selectively stains intestinal metaplasia in BE, including cells with dysplasia .
In our own ongoing trial we can confirm that the application of methylene blue results in a dark blue coloration of columnar epithelium invaded by cancer or intestinal metaplasia. Normal esophageal mucosa appeared unchanged and from these findings, cancer and intestinal metaplasia were clearly distinguishable from other diseases of the esophageal mucosa. Double staining with Lugol's solution and methylene blue, to make the squamocolumnar junction more pronounced, did not increase the incidence of positive biopsies.
It is essential for the dying method with methylene blue, that the mucosa is not exposed to any mucus. The use of a mucolytic agent before the administration of methylene blue is highly recommended. Although the mechanism of methylene blue dying is not known at present, it seems, that changes of the nature of cells and the mucus or the abnormal secretion of pathological mucus may play a role in the dying process. This certainly needs further investigation.
In conclusion, at the present time single staining with methylene blue seems to be the diagnostic method of choice in detecting cancer or intestinal metaplasia in esophageal columnar epithelium. The mechanism still needs further investigation as well as more clinical data are needed to finally judge its routine use.
12. Canto M, Setrakian S, Chak A, et al. Methylene blue-directed biopsy for improved detection of intestinal metaplasia and dysplasia in Barrett's esophagus: a controlled sequential trial. Gastrointest Endosc 1996;43:332(A165).