Diagnosis of early gastric cancer using image enhanced endoscopy: a systematic approach

Abstract

This paper provides an overview of the principles of a vessel plus surface (VS) classification system to explain the diagnostic system of early gastric cancer using image-enhanced magnifying endoscopy. Furthermore, this paper introduces the magnifying endoscopy simple diagnostic algorithm for gastric cancer (MEADA-G) developed according to the VS classification system, with a description of the procedures performed for diagnosis. In addition to the diagnostic system, white opaque substance (WOS), light blue crest (LBC), white globe appearance (WGA), and vessels within epithelial circle (VEC) patterns, which are representative findings that can be observed in the gastric mucosa by image-enhanced magnifying endoscopy, are also described. Image-enhanced magnifying endoscopy is particularly useful in the diagnosis of differentiated-type early gastric cancer. It is important to use the appropriate clinical strategies based on a comprehensive understanding of the usefulness and limitations of the diagnostic system described in this paper.

Keywords: Image-enhanced endoscopy; diagnostic system; early gastric cancer; magnifying endoscopy.

Figure 1

Microanatomies as visualized using magnifying endoscopy with narrow band imaging (NBI) in the stomach. (A) Magnifying endoscopic image with NBI of normal gastric fundic gland mucosa. (B) Correspondence between the magnifying endoscopic image with NBI and histological findings of normal gastric fundic gland mucosa. (C) Magnifying endoscopic image with NBI of normal gastric pyloric gland mucosa. (D) Correspondence between the NBI-combined magnifying endoscopic image and histological findings of normal gastric pyloric gland mucosa. NBI, narrow-band imaging; SEC, subepithelial capillary; MCE, marginal crypt epithelium; CO, crypt opening; CV, collecting venule; IP, intervening part. [Reprinted from (14)].

Figure 2

VS classification using magnifying endoscopy with NBI. The microvascular pattern (V) is classified as regular/irregular/absent, as is the microsurface pattern (S) (the yellow arrows denote a demarcation line). VS, vessel plus surface; NBI, narrow-band imaging. [Reprinted from (3)].

Figure 3

A strategy for magnifying endoscopy with NBI in screening gastroscopy. C-WLI, conventional endoscopy with white light imaging; M-NBI, magnifying endoscopy with narrow-band imaging; NBI, narrow-band imaging. [Reprinted from (5)].

Figure 4

Difficult case of magnifying endoscopic diagnosis using the VS classification system. Demarcation line, absent, irregular MV pattern, absent, irregular MS pattern, absent. (A) Conventional endoscopic image. A well-demarcated slightly depressed pale lesion is present in the greater curvature of the gastric antrum (yellow arrow). (B) Magnifying endoscopic image with NBI [the highest magnification of the yellow squared area of (A)]. It was judged that there are no abrupt changes in capillaries underneath the mucosal epithelium or MCE in both background mucosae to the lesion. Accordingly, a demarcation line is absent. The shapes of individual microvessels are homogeneous, showing a symmetrical distribution and regular arrangement. Thus, the pattern was judged to be a regular MV pattern. Regarding the MS pattern, the marginal crypt epithelium is oval, showing homogeneous shapes, a symmetrical distribution, and a regular arrangement. Thus, the pattern was judged to be a regular MS pattern. Therefore, the lesion had the regular MV pattern plus regular MS pattern without a demarcation line, and according to the VS classification system, a diagnosis of non-cancerous lesion was made. However, histopathologically, the lesion was diagnosed as signet ring cell carcinoma. These discolored undifferentiated-type cancer lesions represent difficult cases to diagnose using magnifying endoscopy, requiring a biopsy to establish a definitive diagnosis. VS, vessel plus surface; MV, microvascular; MS, microsurface; NBI, narrow-band imaging; MCE, marginal crypt epithelium.

Figure 5

Magnifying endoscopy simple diagnostic algorithm for early gastric cancer (MESDA-G). VS, vessel plus surface; IMVP, irregular microvascular pattern; IMSP, irregular microsurface pattern. [Reprinted with some modifications from (3)].

Figure 6

Example of application of MESDA-G (I). Demarcation line: absent. (A) Conventional endoscopic image. A flat reddish mucosal lesion is present in the posterior wall of the gastric antrum (yellow arrow). (B) Magnifying endoscopic image with NBI. Subepithelial capillaries are gradually dilated in non-reddish to reddish areas. Furthermore, there is a gradual change in the shape of MCE. More specifically, there is no identifiable abrupt change in the border area between the MV and MS patterns. Thus, the demarcation line was judged to be absent. A diagnosis of non-cancerous lesion was made according to MESDA-G. MESDA-G, magnifying endoscopy simple diagnostic algorithm for gastric cancer; NBI, narrow-band imaging; MCE, marginal crypt epithelium; MV, microvascular; MS, microsurface.

Figure 7

Example of application of MESDA-G (II). Demarcation line: present; irregular MV pattern: absent; irregular MS pattern: absent. (A) Conventional endoscopic image. A regional, slightly concave reddish lesion is present in the posterior wall of the gastric corpus (yellow arrow). (B) Magnifying endoscopic image with NBI. There is an abrupt change in the MV and MS patterns at the site indicated by the yellow arrows. Namely, a demarcation line is present. In this case, the VS classification of the MV and MS patterns inside the demarcation line was carried out according to MESDA-G to judge the presence or absence of the irregular MV pattern and/or irregular MS pattern. In the MV pattern, the shapes of individual microvessels are homogeneous, showing a symmetrical distribution and regular arrangement. Therefore, this case was judged to have a regular MV pattern. Regarding the MS pattern, the MCE has an oval morphology, showing homogeneous shapes, a symmetrical distribution, and a regular arrangement. There are regular light blue crests in glandular openings arranged regularly. Based on these findings, the case was judged to have a regular MS pattern. Therefore, the lesion was judged to have a regular MV pattern plus regular MS pattern according to the VS classification system, resulting in a diagnosis of non-cancerous lesion. MESDA-G, magnifying endoscopy simple diagnostic algorithm for gastric cancer; MV, microvascular; MS, microsurface; NBI, narrow-band imaging; VS, vessel plus surface; MCE, marginal crypt epithelium.

Figure 8

Example of application of MESDA-G (III). Demarcation line: present; irregular MV pattern: present; irregular MS pattern: present. (A) Conventional endoscopic image. There is a well-demarcated depressed lesion accompanied by irregular redness in the lesser curvature of the gastric antrum (yellow arrow). (B) Magnifying endoscopic image with NBI [yellow square area in (A)]. A clear demarcation line is seen in the border area (yellow arrows). Regarding the MV pattern inside the demarcation line, each microvessel has an irregular loop morphology. The microvessels show heterogeneous shapes, an asymmetrical distribution, and an irregular arrangement. Therefore, the pattern was judged to be an irregular MV pattern. Regarding the MS pattern, there are some areas devoid of MCE, which were judged to have an absent MS pattern. In areas where MCE is visible, each has an arcuate MCE morphology, that is, shapes of MCE are heterogeneous, with an asymmetrical distribution and irregular arrangement. The case was judged to have an absent/irregular MS pattern. Based on these findings, the pattern was judged to be an irregular MV pattern plus absent/irregular MS pattern according to the VS classification system, and a diagnosis of cancer was made. MESDA-G, magnifying endoscopy simple diagnostic algorithm for gastric cancer; MV, microvascular; MS, microsurface; NBI, narrow-band imaging; MCE, marginal crypt epithelium; VS, vessel plus surface.

Figure 9

Low-grade adenoma having regular WOS (non-cancer). (A) Conventional endoscopic image (white light). A discolored, flat-elevated lesion (yellow arrow) is present in the anterior wall in the lower part of the gastric corpus. (B) Magnifying endoscopic image with NBI [the highest magnification of the yellow squared area of (A)]. WOS inside the demarcation line is highly dense and large and is localized in the intervening part. WOS shows homogeneous shapes, a symmetrical distribution, and a regular arrangement, leading to the judgment of a regular MS pattern (regular WOS). Microvascular structures are not visible because of the presence of WOS; therefore, the pattern was judged to be an absent MV pattern. According to the VS classification system, the result was an absent MV pattern plus regular MS pattern with a demarcation line, and a diagnosis of non-cancerous lesion was made. Histopathologically, the lesion was a low-grade tubular adenoma. WOS, white opaque substance; NBI, narrow-band imaging; MS, microsurface; MV, microvascular; VS, vessel plus surface.

Figure 10

Well-differentiated adenocarcinoma (cancer) judged to have irregular WOS. (A) Conventional endoscopic image (white light). A discolored, elevated lesion (yellow arrow) is present in the lesser curvature in the lower part of the gastric corpus. (B) Magnifying endoscopic image with NBI [the highest magnification of the yellow squared area shown in (A)]. WOS inside the demarcation line shows heterogeneous shapes, a symmetrical distribution, and an irregular arrangement, leading to the judgment of an irregular MS pattern (irregular WOS). Microvascular structures are not visible because of the presence of WOS, and the pattern was judged to be an absent MV pattern. According to the VS classification system, the result was an absent MV pattern plus irregular MS pattern with a demarcation line, leading to a diagnosis of cancer. Histopathologically, the lesion was very-well-differentiated tubular adenocarcinoma. WOS, white opaque substance; NBI, narrow-band imaging; MS, microsurface; MV, microvascular; VS, vessel plus surface.

Figure 11

Mucosa that is positive for LBC. (A) Magnifying endoscopic image with NBI showing LBC at the edge of the MCE. (B) Histopathological appearance with hematoxylin and eosin (H&E) staining (magnification ×20) showing goblet cells within the crypt epithelium, and a brush border visible at the epithelial surface. (C) Histopathological appearance with Alcian blue periodic acid-Schiff staining (magnification ×20) showing goblet cells and a clearly visible brush border. (D) Immunohistochemical staining (CD10, magnification ×20): the brush border (yellow arrows) on the absorption epithelium surface of intestinal metaplasia becomes CD10 positive. LBC, light blue crest; NBI, narrow-band imaging; MCE, marginal crypt epithelium. [Reprinted from (17)].

Figure 12

Low-grade adenoma(non-cancer) in which LBC is useful for border of the tumor. (A) Conventional endoscopic image (white light). A discolored, flat-elevated lesion (yellow arrow) is present in the lesser curvature in the gastric corpus. (B) Magnifying endoscopic image with NBI [the highest magnification of the yellow squared area shown in (A)]. There is LBC-positive intestinal metaplasia around the lesion, and the line of discontinued LBC is consistent with the border of the tumor (yellow arrows). The tumor was histologically low-grade tubular adenoma. LBC, light blue crest; NBI, narrow-band imaging.

Figure 13

Case presentation of WGA. (A) Conventional endoscopic image (white light). A reddened, regional, flat mucosal lesion is present in the posterior wall of the lesser curvature in the upper part of the gastric corpus (yellow arrow), and white spots are seen in marginal areas of the lesion. (B) Magnifying endoscopic image with NBI. It was confirmed that the white spots observed on conventional endoscopy (white light) are WGAs (white arrows). WGA is characteristically found in the cancerous mucosa very close to the demarcation line (yellow arrows). WGA, white globe appearance; NBI, narrow-band imaging.

Figure 14

Case presentation of VEC pattern. (A) Conventional white light endoscopic findings of early gastric cancer (0−IIa type). A superficial elevated lesion (yellow arrow) is present on the lesser curvature of the gastric antrum. (B) Magnifying endoscopic image with NBI. Within the demarcation line (yellow arrows), the VEC pattern can be seen. An irregular microvascular pattern is observed in the circular intervening part between crypts lined by circular marginal crypt epithelium. (C) Histopathological findings. Hematoxylin and eosin (H&E) stain (magnification ×40). Well-differentiated exophytic carcinoma with elongated finger-like processes lined by cylindrical or cuboidal cells supported by a fibrovascular connective tissue core. NBI, narrow-band imaging; VEC, vessels within epithelial circle. [Reprinted from (30)].