Surgical Science, 2012, 3, 494-498
http://dx.doi.org/10.4236/ss.2012.310098 Published Online October 2012 (http://www.SciRP.org/journal/ss)
Laparoscopic Submucosal Dissection for Gastro intestinal
Stromal Tumor of the Stomach: A Novel Technique for
Local Excision with a Minimal Curative Margin
Norihito Wada1*, Yoshiro Saikawa1, Hiroya Takeuchi1, Tsunehiro Takahashi1, Rieko Nakamura1,
Hirofumi Kawakubo1, Kaori Kameyama2, Makio Mukai2, Yuko Kitagawa1
1Department of Surgery, School of Medicine, Keio University, Tokyo, Japan
2Departments of Pathology, School of Medicine, Keio University, Tokyo, Japan
Received June 16, 2012; revised July 28, 2012; accepted August 9, 2012
ABSTRACT
Background: Laparoscopic wedge resection is accepted as a curative treatment for small- and medium-sized gastroin-
testinal stromal tumors (GISTs) of the stomach. Conventional methods involving surgical staplers require relatively
large lateral margins, which may cause deformity and postoperative dysfunction of the gastric remnant. In this study,
we introduce a novel technique called laparoscopic submucosal dissection (LSD) in which the defects of the stomach
are minimized and a microscopic negative margin is secured. Methods: The normal seromuscular layer of the gastric
wall was dissected with a 5 mm lateral margin. Then, the submucosal tissue was divided carefully using a monopolar
electrosurgical device with a curved spatula tip. Results: The operation time was 170 min, and the amount of bleeding
was very small. We confirmed an intact pseudo-capsule and marginal subserosal or submucosal tissue of the tumor by
histological analysis. The postoperative course was uneventful with no complications. Endoscopy showed minimal de-
formity of the gastric remnant. Conclusion: We think that LSD is a curative and less invasive treatment for GIST of the
stomach. Further investigations are necessary to evaluate the oncological and functional outcomes of this procedure.
Keywords: Gastrointestinal Stromal Tumor; Submucosal Tumor; Endoscopic Submucosal Dissection; Wedge
Resection; Laparoscopic Surgery; Minimally Invasive Surgery
1. Introduction
Gastrointestinal stromal tumors (GISTs) represent only
0.1% to 3% of all gastrointestinal malignancies, but they
are the most common (approximately 80%) mesenchymal
tumors of the gastrointestinal tract [1]. The estimated inci-
dence of GIST is 10 - 20 per million people per year. These
tumors can arise from throughout the gastrointestinal tract,
but 60% arise from the stomach [2]. Relatively small
GISTs are usually asymptomatic and diagnosed incident-
tally as submucosal tumor (SMT) of the stomach. Although
the management of gastric SMTs used to be controversial,
Japanese guidelines for GIST [3] recommended that his-
tologically established GIST is an indication for surgery
regardless of the size of the tumor. Furthermore, laparo-
scopic surgery can be considered if the tumor is 5 cm or
less. Principles of GIST surgery include complete surgical
resection, no injury to the pseudo-capsule, a macroscopi-
cally negative margin with an adequate safety margin, and
partial resection without prophylactic lymph node dissection
[3-5]. When these criteria are met, laparoscopic surgery is
indicated for patients with small- or medium-sized GISTs
of the stomach.
In laparoscopic wedge resection, stapled sutures are
preferred in most cases [6] because this is a simple and
easy method. However, excessive amounts of the normal
gastric wall may be resected along with the tumor, re-
sulting in deformity of the gastric remnant and some-
times malfunction of the stomach. In this study, we pre-
sent a novel technique called laparoscopic submucosal
dissection (LSD), in which defects of the stomach are
minimized and the cu rative margin is secured.
2. Materials and Methods
2.1. Patient
A 52-year-old man with an SMT (26 mm in diameter) in
the middle body of the stomach visited our hospital. This
patient was asymptomatic and was otherwise healthy. A
gastric SMT was diagnosed 5 years ago. The diameter of
the tumor had increased from 16 to 26 mm. An abdomi-
nal computed tomography (CT) scan (Figure 1(a)),
X-ray (Figure 1(b)), endoscopy (Figure 1(c)), and en-
doscopic ultrasonography (Figure 1(d)) revealed typical
*Corresponding a uthor.
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opyright © 2012 SciRes. SS

N. WADA ET AL. 495
(a)
(b)
(c)
(d)
Figure 1. Preoperative evaluation of the tumor. Computed
tomography (CT), X-ray, endoscopy, and endoscopic ultra-
sonography revealed typical findings of a gastric mesen-
chymal tumor located in the lesser curvature of the gastric
body. (a) Enhanced CT scan; (b) Barium meal X-ray; (c)
Endoscopy; (d) Endoscopic ultrasonography.
findings of gastric mesenchymal tumors located in the
middle part of the lesser curvature. Written informed
consent was obtained for this surgery.
2.2. Surgical Procedures
All the surgical procedures were performed laparoscopi-
cally with the patient under general anesthesia and in th e
supine position. The split leg position was used to allow
the laparoscopist to stand between the patient’s legs. The
primary surgeon stood on the patient’s right with th e first
assistant on the left. Five laparoscopic ports were created
in the patient’s upper abdomen. Pneumoperitoneum with
carbon dioxide under a pressure of 8 - 10 mm Hg was
created. A high-definition 10-mm flexible laparoscope
was inserted through the 12-mm port in the inferior um-
bilical area.
To confirm the location of the tumor, the serosal side
of the gastric wall was carefully observed (Figure 2(a)).
The tumor was found to be located in the middle part of
the lesser curvature and was covered with an intact se-
rosa. The lesser omentum was dissected with ultrasonic
coagulation scissors. The seromuscular layer of the nor-
mal gastric wall adjacent to the tumor was dissected by
use of a monopolar electrosurgical device (ForceTri-
Verse® in conjunction with Opti2® electrodes, Covidien,
MA) with an energy platform (ForceTriad®, Covidien,
MA). The normal muscular layer surrounding the tumor
is important for handling the tumor because direct grasp-
ing of the tumor might cause it to rupture. We secured a
5-mm lateral margin around th e tumor. After the submu-
cosal and proper mucosal layers underneath were ob-
served, we carefully used the LSD method with a mo-
nopolar electrosurgical device. Blunt dissection is a safe
and reliable technique to prevent injury to the tumor or
proper mucosal layer. Moreover, a curved spatula tip is
preferable because small vessels are easily coagulated
and dissected bluntly with this type of an electrode tip
(Figure 2(b)). After the resection was completed, the
tumor was immediately collected in a bag. Intact proper
mucosal layer was observed at the bottom of the gastric
wall defect (Figure 2(c)).
All the laparoscop ic procedures wer e carefu lly performed
without any damage to the pseudo-capsule of the GIST.
Throughout the d issection, the active blade of the ultrason ic
coagulation device was placed on the opposite side of the
tumor. The seromuscular layer was laparoscopically ap-
proximated with monofilament absorbable strings (Fi gure
2(d)). Intraoperative endoscopy was effectively used to con-
firm that the mucosa was unbroken and that the stomach
was airtight a fter serosal closure (Figure 2(e) ).
3. Results
This procedure was performed safely without any intraop-
erative complications. The operation time was 170 min,

N. WADA ET AL. 496
(a) (b) (c)
(d) (e)
Figure 2. (a) Laparoscopic view of the gastric gastrointestinal stromal tumor (GIST). The tumor was located in the middle
part of the lesser curvature and was covered with an intact serosa; (b) Laparoscopic submucosal dissection (LSD). The tumor
had a sufficient lateral margin of normal gastric wall around it and was handled with an atraumatic-hollow jaw grasper,
which does not grasp the tumor itself but grasps the brim of the tumor. The tumor had an intact pseudo-capsule and was
covered with submucosal tissue on the mucosal surface. A curved spatula tip is preferable for blunt dissection during LSD; (c)
Laparoscopic view of the gastric wall after the tumor was removed. The tumor was collected in a bag. Intact proper mucosal
layer was observed at the bottom of the gastric wall defect; (d) Laparoscopic view after the seromuscular layer was appr oxi-
mated with monofilament absorbable strings; (e) Endoscopic view after seromuscular closure. Intraoperative endoscopy con-
firmed the closed mucosa after LSD and air tightness of the stomach.
and the amount of bleeding was very small. The size of
the tumor was 30 × 28 × 25 mm with an exophytic growth
pattern. The tumor was covered with an intact pseudo-
capsule. Immunohistochemical analysis showed that it
was positive for KIT and CD34 but negative for SMA,
desmin, and S-100, which indicates that the tumor was a
GIST. Mitosis was observed 3/50HPF with 2% - 3%
MIB-1-positive cells. Histological analysis showed that
the tumor was covered with an intact p seudo-capsule and
subserosal tissue (Figure 3(a)), and the presence of mar-
ginal submucosal tissue on the pseudo-capsule was con-
firmed (Figure 3(b)). A mutation in the c-kit gene was
detected in the coding region of exon 11.
The postoperative course was uneventful with no
complications. The patient’s dietary intake and body
weight remained unchanged after surgery. No adjuvant
therapy was administered. We followed the patient for 21
months with periodic CT scanning and upper gastrointes-
tinal endoscopy, but we did find any signs of recurrence
or postoperative complaints. Deformity of the area of
excision was minimal, and stenotic changes were not
observed (Figure 4).
4. Discussion
We have reported the operative indications for relatively
small GISTs of the stomach [7]. Surgical resection is the
gold standard for treatment of nonmetastatic primary
GISTs as indicated in published guidelines [3,4]. The
principles of GIST surgery include no injury to the
pseudo-capsule and macroscopically negative margins
[3]. In this context, th e laparoscopic approach to surgical
treatment of gastric GIST is a safe and effective option
for patients with small- and medium-sized tumors if
treated appropriately [8-10]. In this study, we secured a 5
mm lateral margin around the tumor, and normal muscu-
lar tissue was used to handle the tumor to avoid injury to
the pseudo-capsule of the GIST. Furthermore, we care-
fully dissected the submucosal tissue under the magnified
view afforded by the laparoscope, and the presence of
marginal submucosal tissue was confirmed by histological
analysis. This dissection method would be difficult for use

N. WADA ET AL. 497
(a)
(b)
Figure 3. Histology of the resected specimen (hematoxylin
and eosin stain). (a) Serosal side of the tumor (original
magnification ×40). The tumor was covered with an intact
pseudo-capsule and subserosal tissue; (b) Mucosal side of
the tumor (original magnification ×200). Intact pseudo-
capsule and marginal submucosal tissue were confirmed by
histological analysis.
Figure 4. Postoperative endoscopy after 15 months. Stenosis
and significant deformity were not observed.
in open surgery because the resolution of the human eye
would not be sufficient to distinguish the adequate layer
for dissection. Laparoscopic surgery enables us to divide
the submucosal tissue precisely and to find a microscopi-
cally negative margin. In this aspect, endoscopic submu-
cosal dissection (ESD) is comparable with LSD. The
ESD method has been established as a promising endo-
scopic therapy for early gastric cancer [11]. The vertical
margin of the tumor is clearly visualized in ESD. In LSD,
the submucosal layer can also be seen as clearly, which
enables us to create a secure margin during submucosal
dissection.
Katoh and coworkers reported the endoscopic enuclea-
tion of gastric GISTs [12]. The indication of endoscopic
enucleation is limited to tumors arising from the submu-
cosa leaving the muscularis propria free of the tumor.
Furthermore, the size of the tumor has to be less than 3
cm because larger tumors cannot be retrieved from the
mouth. In this report, the authors showed that tumor re-
section with submucosal dissection can be used to achieve
complete resection of the tumor and for a curative on-
cologic outcome.
The characteristics of LSD include 1) minimal de-
formity of the stomach, 2) clean sur gery without stomach
exploration, and 3) lower costs and smaller ports because
of the lack of stapling devices. However, this procedure
has disadvantages such as 1) unknown oncological valid-
ity, 2) technically advanced surgery, and 3) a relatively
longer operation time. From our limited experience, how-
ever, these drawbacks of LSD are limited, and this new
technique is feasible.
Hiki et al. [13] reported the usefulness of laparoscopic
and endoscopic cooperative surgery (LECS) for gastric
wedge resection of gastric SMT. In comparison with
LECS, LSD can lead to less deformity and create a cleaner
environment during surgery. They have also reported that
the success of the procedure does not depend on tumor
location, such as the vicinity of the esophagogastric junc-
tion or pyloric ring. We performed LSD for a patient
with benign SMT of the cardia, and the results of the
surgery were as good as those for the method pre- sented
here (data not shown).
Natural orifice translumenal endoscopic surgery (NO-
TES) [14] may be a less invasive treatment for gastric
GIST. This type of partial gastrectomy would minimize
the size of the abdominal wound and the amount of post-
operative pain. However, the invasiveness of the NOTES
procedure in the stomach are the same as that for laparo-
scopic surgery. Therefore, LSD would have better out-
comes in terms of surgical site infections and postopera-
tive stomach function.
In LSD, surgical staplers are not required, which
means that the cost and size of the trocars are reduced
compared with conventional laparoscopic surgery.

N. WADA ET AL. 498
5. Conclusion
We suggest that LSD is a curative and less invasive
treatment for GIST of the stomach. Further investigations
are necessary to evaluate the oncological and functional
outcomes of this novel procedure.
6. Disclosure
Drs. N. Wada, Y. Saikawa, H. Takeuchi, T. Igarashi, T.
Oyama, T. Takahashi, R. Nakamura, K. Kameyama, M
Mukai, Y. Kitagawa have no conflicts of interest or fi-
nancial ties to disclose.
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