Patient Report

Yonago Acta Medica 2017;60:59–63

Gastric Schwannoma with Enlargement of the Regional Lymph Nodes Resected
Using Laparoscopic Distal Gastrectomy: Report of a Patient
Shota Shimizu, Hiroaki Saito, Yusuke Kono, Yuki Murakami, Hirohiko Kuroda, Tomoyuki Matsunaga, Yoji
Fukumoto, Tomohiro Osaki and Yoshiyuki Fujiwara

Division of Surgical Oncology, Department of Surgery, School of Medicine, Tottori University Faculty of Medicine, Yonago 683-8504,
Japan

ABSTRACT
Preoperative differential diagnosis of gastric submucosal tumors has generally been difficult because they arecovered with normal mucosa. However, recent advancesin endoscopic ultrasound (EUS)-guided sampling of
submucosal gastrointestinal lesions have made it possible to achieve preoperative differential diagnosis ofgastric submucosal tumors. A 76-year-old woman wasreferred to our hospital with a gastric submucosal tumor.
The tumor was observed in the antrum of the stomach.
It was preoperatively diagnosed as a schwannoma after
immunohistochemical evaluation of a biopsy specimen, obtained using endoscopic ultrasound-guided fineneedle aspiration. A computed tomography scan of theabdomen revealed lymphadenopathies near the tumor
indicating the possibility of lymph node metastasis fromthe gastric tumor. The patient underwent laparoscopic
distal gastrectomy with D1 + lymph node dissection.
The resected tumor was a submucosal tumor measuring
65 × 45 × 35 mm; it was histopathologically diagnosed
as a schwannoma. Resected lymph nodes were enlarged
in the absence of lymph node metastasis as a result ofreactive lymphadenopathy. A definitive preoperative
diagnosis of gastric schwannoma is possible using immunohistochemical staining techniques and EUS-guided sampling techniques. After definitive preoperative
diagnosis of gastric schwannoma, minimal surgery is
recommended to achieve R0 resection.

ultrasound (EUS)-guided sampling of submucosal GI
lesions have made it possible to achieve preoperative
differential diagnosis of gastric submucosal tumors;2 thisenables physicians to easily decide on the optimal treatment strategy. In this report, we present a 76-year-old
woman with preoperative diagnosis of gastric schwannoma with enlargement of the regional lymph nodes ofthe stomach.
PATIENT REPORTAn asymptomatic 76-year-old woman was referred toour hospital because of the presence of a gastric submucosal tumor. The patient underwent appendectomy asa child and cholecystectomy in her 40s. There was no
significant past medical, family, or psychosocial history. The upper GI series showed a smooth-marginatedprotruded lesion at the greater curvature of the antrumof stomach (Fig. 1); upper GI endoscopy revealed that
this lesion measured 38 mm (Fig. 2a). Endoscopic ultrasonography (EUS) showed a well-defined hypoechoic mass arising from the proper muscle layer of thestomach; an endoscopic ultrasound-guided fine needle
aspiration biopsy was performed (Fig. 2b). Histologicalevaluation revealed a spindle cell tumor with a fascicularpattern. Immunohistochemical analysis indicated thatthe tumor was positive for S-100 and negative for c-kit,
CD34, α-SMA, and desmin. The preoperative histological diagnosis was gastric schwannoma. A computed
tomography (CT) scan of the abdomen demonstrated a
protruded lesion measuring 45 × 37 mm at the antrumof the stomach and lymphadenopathies near the tumor(Fig. 3a). The 18-fluorodeoxyglucose (FDG) positronemission tomography (PET) and CT scans indicatedhigh uptake of 18-FDG in the tumor at the antrum of
the stomach [standardized uptake value (SUV) max,
5.89–6.81] and slight uptake in the enlarged lymph node

Key words gastric schwannoma; laparoscopic surgery;submucosal tumor
Mesenchymal tumors of the gastrointestinal (GI) tract
mainly comprise a spectrum of spindle cell tumors that
include gastrointestinal stromal tumors (GISTs), leiomyomas, leiomyosarcomas, and schwannomas.1 Immunohistochemical examination of the specimens obtained
from a tumor is essential to make a definitive diagnosis.
Preoperative differential diagnosis of gastric submucosal
tumors has generally been difficult because they are covered with normal mucosa; this makes it difficult to obtain specimens. However, recent advances in endoscopic

Corresponding author: Hiroaki Saito, MD, PhD
sai10@med.tottori-u.ac.jp
Received 2016 November 14
Accepted 2016 November 28
Abbreviations: CT, computed tomography; EUS, endoscopic ultrasound; FDG, fluorodeoxyglucose; GI, gastrointestinal; GIST, gastrointestinal stromal tumors; HPF, high-power field; PET, positronemission tomography; SUV, standardized uptake value

59

S. Shimizu et al.

(SUVmax, 2.07–2.02)(Fig. 3b). Because of the possibility of lymph node metastasis, we performed laparoscopic
distal gastrectomy with D1 + lymph node dissection.
Macroscopically, the gastric mass covered by mucosa measured 65 × 45 × 35 mm, with the cut surface
having the appearance of a firm lobulated yellowish
white tumor. The tumor was located mainly in the proper muscle layer (Fig. 4). Microscopic examination of
the resected and H and E-stained specimens revealeda spindle cell neoplasm arranged in a palisade mannerwith abundant collagen fibers. There was lymphoid cuffing (Fig. 5a). Immunohistochemical staining revealed
that the tumor cells were positive for S-100 and negative
for c-kit and neurofilaments (Figs. 5b–d). There were notumor cells in the resected enlarged lymph nodes, indicating reactive lymphadenopathies. These histopathological and immunohistochemical findings are consistent
with the presence of a gastric schwannoma with reactive
lymphadenopathies.

Shimizu et al. Figure 1	

DISCUSSION
Schwannomas, in other words neurinomas or neurilemmomas, are benign neurogenic tumors originating from
Schwann cells, which normally wrap around the axonsof the peripheral nerves. Theoretically, schwannomas
can develop anywhere along the peripheral course ofa nerve. However, they most commonly occur in thehead and neck, but rarely in the GI tract. In the GI tract,
the stomach is the most common gastrointestinal siteof schwannoma, which constitute 0.2% of gastric neoplasms.3, 4 The typical presentation of gastric schwannoma is as a submucosal tumor with spindle cell histology.
GIST, which are the most common mesenchymal tumorof the stomach, have the same presentation as gastricschwannoma. Despite strong morphological similarities,
these tumors are heterogeneous regarding their immunophenotypes. In 1988, Daimaru et al. successfully
identified schwannoma as a primary GI tumor based on
Fig. 1. Upper gastrointestinal X-ray showing the smooth-marginpositive S-100 staining.5 GIST also became a distinct GI
ated protruded lesion at the greater curvature of the antrum of thediagnostic
that
Shimizu et al.tumor
Figure2	
category when it was discovered
stomach (arrow).
1,
6
nearly all GIST cells express c-kit protein. Before the

a
(a)	

b
(b)	

Fig. 2. Endoscope image. a: Upper gastrointestinal endoscopy showing the smooth protruded lesion measuring 38 mm at the greater
curvature of the antrum of the stomach. b: Endoscopic ultrasonography image showing a well-defined hypoechoic mass arising from theproper muscle layer of the stomach (arrow).

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Shimizu et al. Figure 3	
Gastric schwannoma resected using laparoscopic surgery

a(a)	

b
(b)	

Fig. 3. CT image. a: CT image showing a protruded lesion measuring 45 × 37 mm at the antrum of the stomach (white arrow), and enlargement of the regional lymph nodes of the stomach (black arrow). b: 18-FDG positron emission tomography CT image showing highuptake of 18-FDG in the tumor at the antrum of the stomach (SUVmax, 5.89–6.81) (white arrow) and slight uptake in the lymph nodes(SUVmax, 2.07–2.02) (black arrow). CT, computed tomography; FDG, fluorodeoxyglucose; SUV, standardized uptake value.

Shimizu et al. Figure 4	

a
(a)	

b
(b)	

Fig. 4. The tumor was located mainly in the proper muscle layer. a: Gastric mass covered by mucosa measuring 65 × 45 × 35 mm, b: withthe cut surface showing a firm lobulated yellowish white tumor.

recognition of S-100 antigen and c-kit antigen in gastricschwannomas and in GISTs, these neoplasms were mostoften classified as leiomyomas, leiomyosarcomas, or
gastrointestinal autonomic nerve tumors.1, 4–6 With theadvent of immunohistochemical staining techniques andultrastructural evaluation, it is now possible to identify
these neoplasms based on their distinct immunophenotypes. Furthermore, recent advances in EUS-guided
sampling of gastrointestinal submucosal lesions makeit possible to make a preoperative differential diagnosis

of gastric submucosal tumors. In fact, in our case preoperative diagnosis of gastric schwannoma was madeby means of an immunohistochemical examination of
specimens obtained from the tumor by EUS-guided
sampling.
Surgical resection is the only possible treatment
for gastric schwannoma.3, 7 The size and location of thetumor, as well as its relationship with the surroundingorgans, are important factors in determining the type ofoperation. Local extirpation, wedge resection, partial,
61Shimizu et al. Figure 5	
S. Shimizu et al.

(a)	
a

(b)	
b

(c)	
c

(d)	
d

Fig. 5. Photomicrographs. a: There was lymphoid cuffing. Bar = 200 µm. b: Tumor cells were positive for S-100 and c: negative for c-kit. d:
Immunostained neurofilaments. Bar = 50 μm.

subtotal or even total gastrectomy, are all acceptable
operations for the complete removal of the tumor.8 Laparoscopic techniques can also be used.9 Lymph node dissection is not required because it has been reported that
gastric schwannoma is a benign tumor and is unlikely
to metastasize to the lymph nodes. In our case, however,there were enlarged lymph nodes with moderate uptakeof 18-FDG; this indicated the possibility of lymph nodemetastasis and the presence of another tumor such as
malignant lymphoma that had developed in the lymph
nodes. Shayanfar et al. reported a schwannoma thatoriginated in the regional lymph nodes of the stomach.10 Furthermore, Murase et al. reported a malignant
schwannoma of the esophagus with lymph node metastasis.11 Considering the possibility of the presence oftumor cells in the enlarged lymph node, we performed
laparoscopic distal gastrectomy with D1+ lymph nodedissection in the present case. Postoperative histopathological examination of the enlarged lymph nodes after
resection revealed that there were no tumor cells present,
indicating the presence of reactive lymphadenopathies.
The correlation between gastric schwannoma and enlarged lymph nodes remains unclear. Because enlarged
lymph nodes are regional lymph nodes and are locatednear the tumor, it is likely that gastric schwannoma can
induce reactive lymphadenopathies. In this regard, the18-FDG positron emission tomography and CT scans

showed high uptake in gastric schwannoma in our case.
Komatsu et al. reported the first case of gastric schwannoma that exhibited increased accumulation of 18-FDG
on PET imaging.12 It has not been clarified why benign
schwannomas show increased 18-FDG uptake on PET;
Kawabe et al. reported that 18-FDG accumulated ininflammatory tissue involving lymphocyte proliferationin chronic tonsillitis.13 It has been reported that cuff-like
lymphoid aggregates are recognized around the tumor
in 97% of gastric schwannomas;14 this also occurred in
the present case. Therefore, it is likely that lymphocyte
proliferation in gastric schwannoma is related to enlargement of the regional lymph node observed in our case.
Thus far, the majority of previous series in the literature
have demonstrated no lymph node metastasis regarding
gastric schwannoma.15, 16 Therefore, local resection of thestomach and extirpation of enlarged lymph nodes might
be sufficient in the present case.
Gastric schwannoma is considered a benign tumor.
It is unclear whether pathological parameters such as
tumor size and mitotic rate have prognostic significancein this tumor, as in the cases of GISTs reported thus far;this is because gastric schwannoma is rare comparedwith GIST and experience concerning their long-term
follow-up is limited. In this regard, Voltaggio et al. reported that some gastric schwannomas exceed 10 cm insize, and a minority have a mitotic rate > 5/50 high-pow62

Gastric schwannoma resected using laparoscopic surgery

er fields (HPFs); none of these 51 gastric schwannoma
cases showed evidence of aggressive behavior.17 Despite
this, these authors advised caution regarding gastricschwannomas with higher mitotic rates (> 10/50 HPFs),
because experience from their long-term follow-up was
limited.17 In fact, one case of malignant gastric schwannoma has been recently reported;18 in this case, immunohistochemistry revealed that the tumor cells were positive for S-100 protein and negative for c-kit and smoothmuscle actin. Mitosis was scattered with 10 mitoses per
50 HPFs, indicating the aggressiveness of this tumor.
This patient died at 5 months after surgery as a result ofmultiple liver metastases. Therefore, careful follow-up
is required in gastric schwannoma patients with higher
mitotic rates (> 10/50 HPFs) after surgery.
A definitive preoperative diagnosis of gastricschwannoma is possible using immunohistochemical
staining techniques and EUS-guided sampling techniques. After definitive preoperative diagnosis of gastricschwannoma, minimal surgery is recommended toachieve R0 resection.

6 Miettinen M, Majidi M, Lasota J. Pathology and diagnostic
criteria of gastrointestinal stromal tumors (GISTs): a review.
Eur J Cancer. 2002;38 Suppl 5:S39-51. PMID: 12528772.
7 Prevot S, Bienvenu L, Vaillant JC, de Saint-Maur PP. Benign
schwannoma of the digestive tract: a clinicopathologic andimmunohistochemical study of five cases, including a case of
esophageal tumor. Am J Surg Pathol. 1999;23:431-6. PMID:
10199472.
8 Bandoh T, Isoyama T, Toyoshima H. Submucosal tumorsof the stomach: a study of 100 operative cases. Surgery.
1993;113:498-506. PMID: 8488466.
9 Basso N, Rosato P, De Leo A, Picconi T, Trentino P, Fantini A,
et al. Laparoscopic treatment of gastric stromal tumors. Surg
Endosc. 2000;14:524-6. PMID: 10890957.
10 Shayanfar N, Shahzadi S. Schwannoma In A Perigastric
Lymph Node: A Rare Case Report. Iran J Pathol. 2008;3:43-6.
11 Murase K, Hino A, Ozeki Y, Karagiri Y, Onitsuka A, Sugie
S. Malignant schwannoma of the esophagus with lymph nodemetastasis: literature review of schwannoma of the esophagus.
J Gastroenterol. 2001;36:772-7. PMID: 11757750.
12 Komatsu D, Koide N, Hiraga R, Furuya N, Akamatsu T,
Uehara T, et al. Gastric schwannoma exhibiting increased
fluorodeoxyglucose uptake. Gastric Cancer. 2009;12:225-8.
PMID: 20047128.
13 Kawabe J, Okamura T, Shakudo M, Koyama K, Wanibuchi H,
Sakamoto H, et al. Two cases of chronic tonsillitis studied by
FDG-PET. Ann Nucl Med. 1999;13:277-9. PMID: 10510887.
14 Hou YY, Tan YS, Xu JF, Wang XN, Lu SH, Ji Y, et al.
Schwannoma of the gastrointestinal tract: a clinicopathological, immunohistochemical and ultrastructural study of 33
cases. Histopathology. 2006;48:536-45. PMID: 16623779.
15 Fujiwara S, Nakajima K, Nishida T, Takahashi T, Kurokawa Y,
Yamasaki M, et al. Gastric schwannomas revisited: has precise preoperative diagnosis become feasible? Gastric cancer.
2013;16:318-23. PMID: 22907486.
16 Zheng L, Wu X, Kreis ME, Yu Z, Feng L, Chen C, et al. Clinicopathological and immunohistochemical characterisationof gastric schwannomas in 29 cases. Gastroenterol Res Pract.
2014;2014:202960. PMID: 24688535.
17 Voltaggio L, Murray R, Lasota J, Miettinen M. Gastricschwannoma: a clinicopathologic study of 51 cases and criticalreview of the literature. Hum Pathol. 2012;43:650-9. PMID:
22137423.
18 Takemura M, Yoshida K, Takii M, Sakurai K, Kanazawa A.
Gastric malignant schwannoma presenting with upper gastrointestinal bleeding: a case report. J Med Case Rep. 2012;6:37.
PMID: 22277785.

The authors declare no conﬂict of interest.

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