Magnifying endoscopic diagnosis of digestive erosions

(肯塔·穆罕默德)，(许树长)

Department of Gastroenterology，Tongji Hospital，Tongji University，School of Medicine，Shanghai 200065，China

Magnifying endoscopic diagnosis of digestive erosions

Keita Mohamed(肯塔·穆罕默德)，Xu Shuchang(许树长)

Department of Gastroenterology，Tongji Hospital，Tongji University，School of Medicine，Shanghai200065，China

Magnifying endoscopy is used to visualize the microstructure and microvascular architecture of gastrointestinal surface mucosa.Microsurface structure of the mucosa includes normal structure，changed structure by inflammation and biological response.Magnifying endoscopy is starting to play an important role in diagnosis of any upper gastrointestinal diseases by assessment of magnified observation.Magnifying endoscopy holds a great deal of promise in the near future because magnifying endoscopic observation is approaching optical biopsy［1］.The aim of this review is to describe recent advances in endoscopic technology and to review the available literature pertaining to the clinical application of these techniques in the diagnosis of digestive erosions diseases.

magnifying endoscopy;erosions;microstructure;microvascular architecture

Identification of pathology by standard electronic video endoscopes depends on the presence of various mucosal lesions such as erosions，plaques，nodules，or ulcers.Certain conditions can be missed on standard endoscopy because they may have very subtle mucosal changes.In recent years，further improvements in the quality and diagnostic ability of the endoscopic image have been the subject of many technological developments.Recent technological advances in miniaturization have allowed for a confocal scanning microscope to be integrated into trans-endoscopic probes enabling endoscopists to see and collect in vivo virtual biopsies of the gastrointestinal mucosa during endoscopy.

1 Term and Concept

Erosions are frequent pathological manifestation of the gastro-duodenal tract.They are often found in histology specimens specially in gastro-intestinal diseases(esophagus，stomach and duodenum).They occur in various pathologic conditions as well for no apparent reason.Frequently they are epiphenomena，accompanying other lesions.Many histological types of erosion are minute and cannot be identified with standard white-light endoscopy，only with magnification or vital staining.With endoscopy，the frequency of detection is even higher according to Kawai et al［2］.The term erosion has been a major problem of endoscopic terminology，similar to the term“gastritis”.Endoscopically this term is acceptable only if the endoscopic criteria are sufficient for identifying the lesions with reasonable certainly.Erosion is essentially an acute lesion that elicits a prompt reaction and quick regeneration of the injured epithelium in a few hours or days without trace.It is an acute flat defect of the mucosa，which don’t penetrate beyond the muscularis mucosa.This is in contrast to an ulcer which heals with a scar［3］.

Endoscopic criteria of mucosal erosions

The defect as such cannot be visualized because it is too shallow.The characteristic feature enabling diagnosis is the presence of exudates covering the defect.It consists of blood components and fibrin.According to the proportion of both constituents，it appears as a fleck on the mucosa，either red(hemorrhage)or yellow(fibrin).After a few hours the blood is clotted or hemolyzed or forms as hematin crust.Fibrin also shrinks into a yellowish lining sticking on the defect.If bleeding prevails，the erosion is designated as hemorrhagic.Later on the remnants of blood may get under the regenerated superficial epithelium and form a petechia or a pigment spot.If fibrin prevails，the erosion is designated as aphthous.As to the shape，erosion are linear or round，and their diameter usually does not exceed a few millimeters.More exten-sive sub epithelial hemorrhages are called ecchymosed or suffusions.In contrast to an ulcer，which is characterized by a distinct base and border，an erosion appears as a fleck with a rather indistinct margin.The difference between the two lesions includes the possibility of drawing an erosion with surrounding mucosa into the lumen with a forceps，in contrast to the ulcer，which firmly adheres to the wall.It has been said that an erosion is essentially an acute lesion.In the present literature the term chronic erosion has been used for a conical elevation 2 to 8 mm in diameter，which has a hemorrhage or aphthous erosion on the top or simply an umbilicated depression.Such a lesion has also been referred to as a raised，elevated，complete or varioliform erosion.This designation is based on the assumption that the erosion is the primary lesion，which results in elevation of the surrounding mucosa.However，the elevation is the primary phenomenon due to accumulation of material within the mucosa which protrudes into the lumen and bursts.The hole through which it empties appears as an erosion，but it is a secondary epiphenomenon.The defect seals with a hematin or fibrin plug，and after reepithelization appears as an umbilicated depression.According to this concept，the erosion is a transient phenomenon in the active stage of the lesion whereas the conical umbilicated elevation is a lasting sequella.With regard to the ensuing confusion，Chronic erosion has been avoided to an adequate descriptive term“papule，”which points to the characteristic endoscopic feature of the lesion.Further attributes specify the lesion as a hemorrhagic papule with a hemorrhagic erosion on the top，an aphthous papule with an aphthous erosion on the top，and an umbilicated papule with an umbilicated depression［4，5］.

Table 1 Endoscopic characteristics of erosion and ulcer

2 The diagnosis methods of erosions lesions

The gastrointestinal diseases cited above in clinical expression are due to primary or secondary erosive lesions of the gastric mucosa.The most diagnostic methods of investigation are through direct biopsies(esophagus，antrum or the body)by the magnifying endoscopy，highlighting the loss of substances from the mucosa.

2.1 In the pharynx and esophagus

Using standard white-light endoscopy，certain conditions such as erosions，nodules，plaques or ulcers can be missed.In addition，the diagnosis of the pathology might not be always accurate［9］.Recently，magnifying endoscope has been used clinically for its developments in amplifying power with the intention of improving the overall accuracy of endoscopy and biopsy.With this technique，good endoscopic visualization of the mucosa is ob-tained but adequate endoscopic biopsies are more difficult to obtain and often too superficial to make a diagnosis in this areas［6－8］.

2.2 In the stomach and colon

The endoscopic appearances of the stomach and colon are poorly known by using standard white light endoscopy.It’s still controversial whether certain macroscopic endoscopic features can be used to diagnose Helicobacter pylori(HP)related gastritis.There is a great deal of ignorance about the normal macroscopic appearance of the gastric mucosal lining.In all probability many of the appearance which endoscopists interpret as“Normal”are presumably not normal.Endoscopic findings such as erythema are frequently labeled as gastritis despite a long recognized lack of evidence supporting a correlation between endoscopic features and histologic gastritis..Gastric mucosal atrophy could be identified by routine endoscopy usually when it was at more severe grade.Under magnifying endoscopy，disordered structures，deficiency and even disappearance of gastric pits are in high detection and accuracy for atrophic gastritis.As to mild and moderated grades of atrophy，the diagnosis by magnifying endoscopy may be higher than that by routine endoscopy［9－11］.

Table 2 Diagnosis by magnifying endoscopy in upper GI tract

2.3 In the small intestine

Endoscopic examination of the small intestine with standard endoscopy for detection of erosive lesions is very difficult.The upper and pan endoscopy ileocolonoscopy do consider the very small portion of proximal small intestine，distal respectively.In m，ost clinics instead，a colonoscope may be used as a partial enteroscopy with probes and special endoscopic techniques.Endoscopic images obstenues of intestinal erosions were reliable and well interpreted with a good preparation［12，13］.

3 Clinical application of confocal scanning endoscope

Confocal laser scanning is a cutting-edge endoscopic procedure that enables the surface of the gastrointestinal mucosa to be microscopically examined during the endoscopy.With Confocal scanning，the physician is able to make a real-time diagnosis of different GI diseases［14－16］.

New model of electronic magnifying endoscope GIF Q-240Z(Olympus Optical Co.，Ltd.，Tokyo，Japan)the Pentax EG-3870CIK(upper endoscope)and EC-3870CILK(colonoscope(Pentax，Tokyo，Japan)was used.It could be used to perform routine endoscopy(observation at standard magnification)as well as to magnify the image 80 times［17－19］.

Confocal laser endoscopy is a novel topic in the field of digestive endoscopy to diagnose minute erosions lesions in gastric mucosa by magnifying endoscopy with a high degree of accuracy and can facilitate rapid diagnosis during routine endoscopy.

3.1 In the esophagus and pharynx

Endoscopy is a widely used diagnostic tool for several different inflammatory and neoplastic pathologies of the mucosa of the esophagus.Unfortunately，it is quite difficult to detect these lesions under the standard white light endoscopy especially in patients with minimal change esophageal reflux disease(MERD)，but also particularly by inexperienced endoscopists(kappa value for interobserver agreement by inexperienced endoscopist for minimal change was reported to be low and ranged be-tween 0.19 and 0.36).In the oropharyngeal area so far the tongue is the only region that can be see by this new technique.

Over a few years，endoscopic technologies have evolved tremendously including high resolution and magnification digital chromoendoscopy.These technologies are practically useful for detecting various subtle lesions along the gastrointestinal(GI)tract starting from esophagus to colon.Other than the detection of subtle change reflux esophagitis，Standard，simple and precise endoscopic reading criteria for the identification of MERD are also required，these have proven to be beneficial for Barrett’s epithelium detection，targeted biopsy of the suspicious area in gastric intestinal metaplasia and detecting early gastric and colon cancers.

Confocal Laser Scanning is an important tool with a high potential for GERD diagnosis particularly for MERD since it provides the endoscopist with a simple，safe and rapid method for a better detection of subtle esophageal lesions.This technology is suitable for epithelial evaluation of the anterior parts(buccal area，tongue，and door of the mouth).

In our speculation，over the next few years it may become a standard tool for GERD and MERD diagnosis in clinical practice［20－23］.

3.2 In the stomach and colon

The fine detail of the structure of the gastrointestinal mucosa is not delineated during conventional white light endoscopy.Recent advances in endoscopy have facilitated the detection of the diseases.

In gastrointestinal endoscopy，magnifying endoscope have primarily been utilized to enhance the detection of diseased areas，to guide endoscopics biopsies，and to obtain better visual diagnosis or characterization of small abnormalities.The distal border of the normal fundic type of mucosa in the stomach can be recognized easily because of the differences in mucosal characteristics and the pattern of the gastric area.A small erosion which produces a very shallow depression without elevation of the surrounding mucosa is very difficult to detect endoscopically.With this new technique，it is effective to recognize such lesions and to define their size，shape，number and distribution in the detection of early gastric cancer，especially of minute diagnosis and typeⅡb carcinoma(superficial flat type)，and in recognizing the extent of cancer infiltration.

This new tool is useful in differentiating benign from malignant ulcers and may aid in determining whether or not an ulcer is recurrent by direct in vivo identification of Helicobacter pylori infection.

In patients with suspected celiac disease，confocal endomicroscopy can demonstrate villous atrophy and an increased number of intraepithelial lymphocytes，enabling immediate in vivo diagnosis of celiac disease.The presence of neoplastic changes in a colonic mucosa can be predicted with high accuracy.Confocal Laser Scanning has several potential roles in polyp management from adenomatous polyps by surface characteristics to the flat neoplasms of the colon.In patients with long-term ulcerative colitis，chromoscopy with supplemental CEM has recently been shown to further increase the yield for intraepithelial neoplasia.Magnifying endoscopy has also the capacity to differentiate normal from inflamed tissue，and thus target biopsies for the purpose of grading and mapping the extent of colitis.Confocal Scanning can also be helpful for the diagnosis of microscopic colitis in patients with chronic diarrhea.In patients with collagenous colitis，it allows direct in vivo visualization of collagenous bands under the epithelial layer of the colon，and in patients with lymphocytic colitis，it can demonstrate crypt distortion and an increased distance between the colonic crypt.Thus，Confocal Scanning has the potential to replace or direct a large number of random biopsies in patients with chronic diarrhea，where the confocal image is normal［24－26］.

4 Conclusion

The elaboration of a precise and clear diagnosis of gastrointestinal erosive disease has often been a major problem.It has become a source of confusion and incomprehension in the area of endoscopy because many histological erosions are minute and therefore cannot be identified using standard white-light endoscopy.In the region pharyngeal-esophagus as in the stomach and colon establishment adequate and clear diagnosis has always been a difficult problem and in correlation with histological biopsy.With the recent progress of science in the medical imaging，precision and overall good Interpretation of endoscopic images confocal laser endoscopy is used with precision and overall good interpretation of endoscopic images.

Confocal scanning is a rapidly emerging field of gastroenterology that bridges the interface between endoscopy and histology by magnifying endoscopy with a high degree of accuracy and can facilitate rapid diagnosis during routine endoscopy.It further expands our ability to image living tissue in real time and to provide therapy in the same setting.The main advantages of the advanced endoscopic imaging techniques in the management of gastrointestinal lesions are to identify abnormal mucosal and vascular patterns，to obtain targeted biopsy samples from high-yield areas，and perhaps to avoid biopsy samples from non dysplastic areas.

It is a novel topic in the field of digestive endoscopy to diagnose minute lesions in gastric mucosa by magnifying endoscopy.High resolution magnifying is superior to standard endoscopy for the diagnosis of H.pylori gastritis，and identification of specific histopathology features such as atrophy and intestinal metaplasia seems possible［27－32］.Magnifying endoscopy therefore holds a great deal of promise in the near future since observation is now approaching optical biopsy.

Abbreviation

GERD:gastro esophageal reflux disease

MERD:Multiple esophageal reflux disease

CEM:confocal endomicroscopy

LPRD:Laryngopharyngeal reflux disease

IM:intestinal metaplasia

SCC:Squamous cell carcinoma

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