Difficulties in the preoperative diagnosis of gastrointestinal submucosal tumors by
endoscopic ultrasonography and errors of tissue sampling may make invasive surgery
[1] or endoscopic resection [2] inappropriate for their removal. Better methods of diagnosing submucosal tumors
are therefore needed. We have found that bloc biopsy and use of the submucosal endoscopy
with a mucosal flap (SEMF) method [3] under direct vision can assist in the diagnosis of submucosal tumors [4]
[5]. This method has the advantage of assessing the macroscopic characteristics of submucosal
tumors. These endoscopically visualized features, identified by endoscopic imaging
under direct view through a dissected submucosal tunnel, include the color, clarity,
shape, and solidity of the tumor. Here, we describe the representative endoscopically
visualized features of different types of gastric submucosal tumors.
Bloc biopsy with the SEMF method consists of five major steps: SEMF, endoscopic submucosal
dissection, bloc biopsy to acquire a specimen of sufficient size, tissue collection,
and clip closure of the entry point. After the creation of a tunnel into the submucosa
toward the tumor, the endoscopically visualized features of a submucosal tumor can
be identified in the submucosa ([Fig. 1]). The solidity of a submucosal tumor can be assessed by using a needle‑knife (KD-441Q;
Olympus Medical Systems Corporation, Tokyo, Japan) to apply pressure to the tumor
in the area of the bloc biopsy. Different types of submucosal tumors can be classified
according to four endoscopically visualized features: color, clarity, shape, and solidity.
Gastrointestinal stromal tumors (GISTs) are white, cloudy, round, rigid tumors ([Fig. 2]); leiomyomas are white, clear, round, elastic but hard tumors ([Fig. 3]); heterotopic pancreatic tissue masses are yellowish, multinodular, soft tumors
with surface features specific to pancreatic tissue ([Fig. 4]); gastric cysts are bluish, clear, round, soft tumors with wet surfaces ([Fig. 5]); and lipomas are yellow, soft tumors with characteristics similar to those of adipose
tissue ([Fig. 6]).
Fig. 1 Bloc biopsy with the submucosal endoscopy mucosal flap method. A short tunnel is
created, via an additional submucosal dissection, to access the tumor. The endoscopically
visualized features of the submucosal tumor can be identified in the submucosa.
Fig. 2 Gastrointestinal stromal tumor (GIST) characteristics at submucosal endoscopy: typically
white, cloudy, round, rigid tumors.
Fig. 3 Leiomyoma characteristics at submucosal endoscopy: typically white, clear, round,
elastic but hard tumors.
Fig. 4 Heterotopic pancreatic tissue characteristics at submucosal endoscopy: typically
yellowish, multinodular, soft tumors, with surface features specific to pancreatic
tissue.
Fig. 5 Gastric cyst characteristics at submucosal endoscopy: typically bluish, clear, round,
soft tumors with wet surfaces.
Fig. 6 Lipoma characteristics at submucosal endoscopy: typically
yellow, soft tumors with adipose tissue-like characteristics.
Submucosal tumors may be classified on the basis of features seen at submucosal endoscopy.
These features may have diagnostic value that allows avoidance of unnecessary surgery
([Video 1]).
First, a bloc biopsy is obtained with the submucosal endoscopy mucosal flap method,
which creates a short tunnel via an additional submucosal dissection to access the
tumor. Next, the endoscopically visualized features of each submucosal tumor can be
visually identified in the submucosa. The video shows representative endoscopically
visualized features of different types of gastric submucosal tumors. Gastrointestinal
stromal tumors are white, cloudy, round, rigid tumors; the latter feature is determined
by applying pressure to the tumor with the needle-knife. Leiomyomas are white, clear,
round, elastic but hard tumors. Heterotopic pancreatic tissue tumors are yellowish,
multinodular, soft tumors with surface features specific to pancreatic tissue. Gastric
cysts are bluish, clear, round, soft tumors with wet surfaces. Lipomas are yellow,
soft tumors with adipose tissue-like characteristics.
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