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Gastric schwannoma—a rare benign mimic of gastrointestinal stromal tumor

Gastric schwannoma—a rare benign mimic of gastrointestinal stromal tumor Schwannomas most commonly manifest as acoustic neuromas in the vestibulo-cochlear nerve (CN VIII). These may occur unilaterally as primary tumors, or bilaterally secondary to neurofibromatosis type 2. More rarely, they present in extra- cranial sites, including the gastrointestinal tract. Gastrointestinal schwannomas are believed to arise from Auerbach’s plexus in the muscularis propria, and are classified as mesenchymal tumors. Here, we report a rare case of a 49-year-old woman who had surgical resection of a gastric mass which was eventually diagnosed as gastric schwannoma. appetite, 10 pound weight loss and sore throat of 4 months dur- INTRODUCTION ation. The patient was found to have macrocytic anemia with Mesenchymal tumors of the gastrointestinal (GI) tract are a hemoglobin of 9.2 g/dL and mean corpuscular volume (MCV) of group of tumors that can arise from an array of different tissue 107.5, most likely attributable to her vegetarian diet. On this types. These include leiomyomas, GI stromal tumors (GIST), lip- initial visit, the patient was started on a proton pump inhibitor omas, hemangiomas and the aforementioned, schwannomas (PPI) 40 mg orally once daily for 8 weeks. Twelve weeks later, [1]. Each of these tumors has defining characteristics, but can the patient returned to the clinic with mild improvement of often be misdiagnosed. Schwannomas, for example, can be eas- symptoms, but disclosed that she had an episode of bloody ily mistaken for a GIST or a leiomyoma, when visualized on emesis. In response to this finding, an esophagogastroduodeno- upper endoscopy [2]. What makes each tumor distinct are their scopy (EGD) was scheduled which revealed mild chronic gastri- histologic features, and more specifically, what immunohisto- tis, negative for Helicobacter pylori and a submucosal mass in chemical (IHC) markers they stain positively to. It is important the gastric body (Fig. 1). Biopsy of the mass showed no evidence to make this distinction, because GISTs have the potential for of malignancy. A presumptive diagnosis of GIST was made. malignant conversion, while Schwannomas are benign and car- Computerized tomography (CT) scan of the abdomen was ry a good prognosis [3]. obtained to further evaluate the gastric mass which showed an exophytic 3.2 × 3.7 × 4.1 cm solid homogeneous mass along the greater curvature of the stomach. An endoscopic ultra- CASE REPORT sound (EUS) was scheduled to further evaluate the depth of the A 49-year-old woman with a medical history of hypertension, lesion. EUS showed a 3.5 × 3.0 cm lesion in the body of the stomach, originating in the muscularis propria (Fig. 2). Fine obesity and chronic kidney disease presented to the gastro- enterology clinic complaining of heartburn, nausea, decreased needle aspiration (FNA) was attempted, but was unable to be Received: 0, 0. Revised: 0, 0. Accepted: January 13, 2018 © The Author(s) 2018. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Downloaded from https://academic.oup.com/omcr/article-abstract/2018/3/omy002/4930763 by Ed 'DeepDyve' Gillespie user on 16 March 2018 120 T. Sunkara et al. Figure 1: Esophagogastroduodenoscopy (EGD) showing a submucosal mass in the gastric body Figure 2: Endoscopic ultrasound (EUS) showing a 3.5 × 3cm mass arising from muscularis propria in the body of the stomach (yellow arrow). The other layers identi- fied are muscularis mucosa (red arrow), submucosa (blue arrow) and serosa (green arrow) accomplished due to intervening blood vessels. Due to the cases of gastric schwannomas in the United States from 1970 failed FNA and size of the mass, the patient was referred to sur- to 1999. Their results showed a female to male ratio of ~1.4–1.0, gical clinic for possible surgical resection. The patient under- with a mean age at presentation of 58 [5]. These findings are went successful resection of the mass and the specimen was consistent with our case, in which a gastric schwannoma pre- sent to pathology. To our surprise, the results were negative for sented in a 50-year-old female. Symptoms, when present, can GIST or leiomyoma. Rather, the specimen stained positive for range from mild dyspepsia, to hematemesis and weight loss. S-100 confirming the diagnosis of gastric schwannoma. Biopsy The bleeding is thought to occur due to ulceration of the mass shows the location of the schwannoma with relation to the from reduced tolerance to gastric acid [6]. overlying epithelial layer (Fig. 3), schwannoma demonstrating Gastric Schwannomas are most often encountered as inci- spindle cell histology (Fig. 4) and spindle cells stained under dental findings on upper endoscopy. Their appearance is iden- S-100 confirming schwannoma (Fig. 5). Patient was followed up tical to other mesenchymal tumors in that they are well in the gastroenterology clinic 8 weeks after the surgery at circumscribed with intact overlying mucosa, and can grow in which point patient denied any GI symptoms. an exophytic or endoluminal fashion [1]. They may also be encountered by other diagnostic modalities including CT scan. When visualized on CT scan, gastric schwannomas are round, DISCUSSION well defined, mural masses with homogeneous attenuation [7]. GI schwannomas are a rare entity, comprising only 0.2% of all EUS is another diagnostic modality, which may also serve as a gastric tumors [4]. A recent study compiled 51 documented therapeutic tool. Through EUS, one can obtain a biopsy through Downloaded from https://academic.oup.com/omcr/article-abstract/2018/3/omy002/4930763 by Ed 'DeepDyve' Gillespie user on 16 March 2018 Gastric schwannoma 121 [10]. Treatment of GI schwannomas depends on the size and depth of the mass. New advances in gastroenterology have increased the role that endoscopy plays in the treatment of GI tumors. Techniques such as endoscopic submucosal excava- tion, endoscopic full thickness resection and submucosal tun- neling endoscopic resection provide a non-invasive, safe way to treat sub-epithelial tumors [11]. Despite these new develop- ments, tumors that lie within the muscularis propria, or are >3 cm in size require surgical intervention, due to their high risk of perforation [8, 11]. Considering the fact that schwanno- mas originate in the Auerbach plexus of the muscularis propria, surgical resection is generally the treatment of choice. Our patient’s schwannoma indeed originated in the muscularis pro- pria, and measured >3 cm, making surgical resection the obvi- Figure 3: Biopsy (hematoxylin and eosin stain) showing schwannoma with rela- ous choice. Recurrence of these tumors is also rare. In 2015, an tion to epithelial layer intensive review of literature gathered 137 cases of gastric schwannomas. Of those cases, 105 were followed up, none of which showed recurrence up to 36 months post date of diagno- sis [12]. Tumors that do demonstrate recurrence have been associated with incomplete resection at time of treatment [13]. CONCLUSION Mesenchymal tumors of the GI tract have long been synonym- ous with GISTs, or leiomyomas. Although rare, schwannomas should be added to the differential diagnosis when encounter- ing submucosal tumors on endoscopy or colonoscopy. Thanks to the development of IHC, the distinction between mesenchy- mal tumors can easily be made within minutes. Due to their benign nature and rare recurrence, the diagnosis of gastric schwannoma should provide the patient reprieve at time of Figure 4: Biopsy (hematoxylin and eosin stain) with schwannoma demonstrat- ing spindle cell histology discovery. ACKNOWLEDGEMENTS None. CONFLICT OF INTEREST STATEMENT None of the authors have any form of conflicts of interest. FUNDING The authors received no financial support for the research, authorship and/or publication of this article. ETHICAL APPROVAL Figure 5: Biopsy showing schwannoma staining positive for S-100 stain This case report was approved by the institute’s Institutional Review Board as per its policy. FNA, and assess the depth of the mass. Depending on the depth and size of the mass, one can safely treat, through endo- CONSENT scopic resection [8]. Histologically, GI schwannomas are characterized by spindle Consent for participation was obtained from this patient. cells with wavy cigar shaped nuclei and collagen. They seldom present with the classic Antoni A and Antoni B patterns that GUARANTOR are typical of acoustic neuromas [9]. Interestingly enough, spin- dle cells are also characteristic of GI leiomyomas and GISTs. Tagore Sunkara, MD. This, coupled with their near identical appearance on upper endoscopy, underscores the importance of IHC markers in REFERENCES making a definitive diagnosis. These markers include S-100, CD117 (c-kit), desmin and smooth muscle actin (SMA). GISTs 1. Kang HC, Menias CO, Gaballah AH, Shroff S, Taggart MW, Garg stain positively to CD117 (c-kit); leiomyomas stain positively to N, et al. Beyond the GIST: mesenchymal tumors of the stom- desmin and SMA; and schwannomas stain positively to S-100 ach. Radiographics 2013;33:1673–90. doi:10.1148/rg.336135507. Downloaded from https://academic.oup.com/omcr/article-abstract/2018/3/omy002/4930763 by Ed 'DeepDyve' Gillespie user on 16 March 2018 122 T. Sunkara et al. 2. Shah AS, Rathi PM, Somani VS, Mulani AM. Gastric schwan- ultrasonography. World J Radiol 2010;2:289–97. ISSN 1949. noma: a benign tumor often misdiagnosed as gastrointes- 8470. tinal stromal tumor. Clin Pract 2015;5:775. doi:10.4081/cp. 9. Plesec Thomas P. Gastrointestinal mesenchymal neoplasms 2015.775. other than gastrointestinal stromal tumors: focusing on 3. Wilde BK, Senger J-L, Kanthan R. Gastrointestinal schwan- their molecular aspects. Pathol Res Int 2011;2011:952569. noma: an unusual colonic lesion mimicking adenocarcin- doi:10.4061/2011/952569. 10 pages. oma. Can J Gastroenterol 2010;24:233–6. 10. Vila RDD, Michaelsen MMC, Bonamigo KS, Cerato NL, de 4. Singh A, Mittal A, Garg B, Sood N. Schwannoma of the Garcia VCM, Passos P, et al. Gastrointestinal schwannoma: a stomach: a case report. J Med Case Rep 2016;10:4. DOI10. case report. Arq Bras Cir Dig 2016;29:211. doi:10.1590/0102. 1186/s13256-015-0788-0. 6720201600030019. 5. Voltaggio L, Murray R, Lasota J, Miettinen M. Gastric 11. Li B, Liang T, Wei L, Ma M, Huang Y, Xu H, et al. Endoscopic schwannoma—a clinicopathologic study of 51 cases and interventional treatment for gastric schwannoma: a single- critical review of the literature. Hum Pathol 2012;43:650–9. center experience. Int J Clin Exp Pathol 2014;7:6616–25. www. doi:10.1016/j.humpath.2011.07.006. ijcep.com /ISSN:1936-2625/IJCEP0002097. 6. Yoon W, Paulson K, Mazzara P, Nagori S, Barawi M, Berri R. 12. Hong X, Wu W, Wang M, Liao Q, Zhao Y. Benign gastric Gastric schwannoma: a rare but important differential diag- schwannoma: how long should we follow up to monitor the nosis of a gastric submucosal mass. Case Rep Surg 2012; recurrence? A case report and comprehensive review of lit- 2012:280982. doi:10.1155/2012/280982. 5 pages. erature of 137 cases. Int Surg 2015;100:744–7. DOI:10.9738/ 7. Levy AD, Quiles AM, Miettinen M, Sobin LH. Gastrointestinal INTSURG-D-14-00106.1. schwannomas: CT features with clinicopathologic correlation. 13. Takemura M, Yoshida K, Takii M, Sakurai K, Kanazawa A. Am J Roentgenol 2005;184:797–802. 10.2214/ajr.184.3.01840797. Gastric malignant schwannoma presenting with upper 8. Sakamoto H, Kitano M, Kudo M. Diagnosis of subepithelial gastrointestinal bleeding: a case report. J Med Case Rep 2012; tumors in the upper gastrointestinal tract by endoscopic 6:37. 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Gastric schwannoma—a rare benign mimic of gastrointestinal stromal tumor

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Oxford University Press
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© The Author(s) 2018. Published by Oxford University Press.
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Abstract

Schwannomas most commonly manifest as acoustic neuromas in the vestibulo-cochlear nerve (CN VIII). These may occur unilaterally as primary tumors, or bilaterally secondary to neurofibromatosis type 2. More rarely, they present in extra- cranial sites, including the gastrointestinal tract. Gastrointestinal schwannomas are believed to arise from Auerbach’s plexus in the muscularis propria, and are classified as mesenchymal tumors. Here, we report a rare case of a 49-year-old woman who had surgical resection of a gastric mass which was eventually diagnosed as gastric schwannoma. appetite, 10 pound weight loss and sore throat of 4 months dur- INTRODUCTION ation. The patient was found to have macrocytic anemia with Mesenchymal tumors of the gastrointestinal (GI) tract are a hemoglobin of 9.2 g/dL and mean corpuscular volume (MCV) of group of tumors that can arise from an array of different tissue 107.5, most likely attributable to her vegetarian diet. On this types. These include leiomyomas, GI stromal tumors (GIST), lip- initial visit, the patient was started on a proton pump inhibitor omas, hemangiomas and the aforementioned, schwannomas (PPI) 40 mg orally once daily for 8 weeks. Twelve weeks later, [1]. Each of these tumors has defining characteristics, but can the patient returned to the clinic with mild improvement of often be misdiagnosed. Schwannomas, for example, can be eas- symptoms, but disclosed that she had an episode of bloody ily mistaken for a GIST or a leiomyoma, when visualized on emesis. In response to this finding, an esophagogastroduodeno- upper endoscopy [2]. What makes each tumor distinct are their scopy (EGD) was scheduled which revealed mild chronic gastri- histologic features, and more specifically, what immunohisto- tis, negative for Helicobacter pylori and a submucosal mass in chemical (IHC) markers they stain positively to. It is important the gastric body (Fig. 1). Biopsy of the mass showed no evidence to make this distinction, because GISTs have the potential for of malignancy. A presumptive diagnosis of GIST was made. malignant conversion, while Schwannomas are benign and car- Computerized tomography (CT) scan of the abdomen was ry a good prognosis [3]. obtained to further evaluate the gastric mass which showed an exophytic 3.2 × 3.7 × 4.1 cm solid homogeneous mass along the greater curvature of the stomach. An endoscopic ultra- CASE REPORT sound (EUS) was scheduled to further evaluate the depth of the A 49-year-old woman with a medical history of hypertension, lesion. EUS showed a 3.5 × 3.0 cm lesion in the body of the stomach, originating in the muscularis propria (Fig. 2). Fine obesity and chronic kidney disease presented to the gastro- enterology clinic complaining of heartburn, nausea, decreased needle aspiration (FNA) was attempted, but was unable to be Received: 0, 0. Revised: 0, 0. Accepted: January 13, 2018 © The Author(s) 2018. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Downloaded from https://academic.oup.com/omcr/article-abstract/2018/3/omy002/4930763 by Ed 'DeepDyve' Gillespie user on 16 March 2018 120 T. Sunkara et al. Figure 1: Esophagogastroduodenoscopy (EGD) showing a submucosal mass in the gastric body Figure 2: Endoscopic ultrasound (EUS) showing a 3.5 × 3cm mass arising from muscularis propria in the body of the stomach (yellow arrow). The other layers identi- fied are muscularis mucosa (red arrow), submucosa (blue arrow) and serosa (green arrow) accomplished due to intervening blood vessels. Due to the cases of gastric schwannomas in the United States from 1970 failed FNA and size of the mass, the patient was referred to sur- to 1999. Their results showed a female to male ratio of ~1.4–1.0, gical clinic for possible surgical resection. The patient under- with a mean age at presentation of 58 [5]. These findings are went successful resection of the mass and the specimen was consistent with our case, in which a gastric schwannoma pre- sent to pathology. To our surprise, the results were negative for sented in a 50-year-old female. Symptoms, when present, can GIST or leiomyoma. Rather, the specimen stained positive for range from mild dyspepsia, to hematemesis and weight loss. S-100 confirming the diagnosis of gastric schwannoma. Biopsy The bleeding is thought to occur due to ulceration of the mass shows the location of the schwannoma with relation to the from reduced tolerance to gastric acid [6]. overlying epithelial layer (Fig. 3), schwannoma demonstrating Gastric Schwannomas are most often encountered as inci- spindle cell histology (Fig. 4) and spindle cells stained under dental findings on upper endoscopy. Their appearance is iden- S-100 confirming schwannoma (Fig. 5). Patient was followed up tical to other mesenchymal tumors in that they are well in the gastroenterology clinic 8 weeks after the surgery at circumscribed with intact overlying mucosa, and can grow in which point patient denied any GI symptoms. an exophytic or endoluminal fashion [1]. They may also be encountered by other diagnostic modalities including CT scan. When visualized on CT scan, gastric schwannomas are round, DISCUSSION well defined, mural masses with homogeneous attenuation [7]. GI schwannomas are a rare entity, comprising only 0.2% of all EUS is another diagnostic modality, which may also serve as a gastric tumors [4]. A recent study compiled 51 documented therapeutic tool. Through EUS, one can obtain a biopsy through Downloaded from https://academic.oup.com/omcr/article-abstract/2018/3/omy002/4930763 by Ed 'DeepDyve' Gillespie user on 16 March 2018 Gastric schwannoma 121 [10]. Treatment of GI schwannomas depends on the size and depth of the mass. New advances in gastroenterology have increased the role that endoscopy plays in the treatment of GI tumors. Techniques such as endoscopic submucosal excava- tion, endoscopic full thickness resection and submucosal tun- neling endoscopic resection provide a non-invasive, safe way to treat sub-epithelial tumors [11]. Despite these new develop- ments, tumors that lie within the muscularis propria, or are >3 cm in size require surgical intervention, due to their high risk of perforation [8, 11]. Considering the fact that schwanno- mas originate in the Auerbach plexus of the muscularis propria, surgical resection is generally the treatment of choice. Our patient’s schwannoma indeed originated in the muscularis pro- pria, and measured >3 cm, making surgical resection the obvi- Figure 3: Biopsy (hematoxylin and eosin stain) showing schwannoma with rela- ous choice. Recurrence of these tumors is also rare. In 2015, an tion to epithelial layer intensive review of literature gathered 137 cases of gastric schwannomas. Of those cases, 105 were followed up, none of which showed recurrence up to 36 months post date of diagno- sis [12]. Tumors that do demonstrate recurrence have been associated with incomplete resection at time of treatment [13]. CONCLUSION Mesenchymal tumors of the GI tract have long been synonym- ous with GISTs, or leiomyomas. Although rare, schwannomas should be added to the differential diagnosis when encounter- ing submucosal tumors on endoscopy or colonoscopy. Thanks to the development of IHC, the distinction between mesenchy- mal tumors can easily be made within minutes. Due to their benign nature and rare recurrence, the diagnosis of gastric schwannoma should provide the patient reprieve at time of Figure 4: Biopsy (hematoxylin and eosin stain) with schwannoma demonstrat- ing spindle cell histology discovery. ACKNOWLEDGEMENTS None. CONFLICT OF INTEREST STATEMENT None of the authors have any form of conflicts of interest. FUNDING The authors received no financial support for the research, authorship and/or publication of this article. ETHICAL APPROVAL Figure 5: Biopsy showing schwannoma staining positive for S-100 stain This case report was approved by the institute’s Institutional Review Board as per its policy. FNA, and assess the depth of the mass. Depending on the depth and size of the mass, one can safely treat, through endo- CONSENT scopic resection [8]. Histologically, GI schwannomas are characterized by spindle Consent for participation was obtained from this patient. cells with wavy cigar shaped nuclei and collagen. They seldom present with the classic Antoni A and Antoni B patterns that GUARANTOR are typical of acoustic neuromas [9]. Interestingly enough, spin- dle cells are also characteristic of GI leiomyomas and GISTs. Tagore Sunkara, MD. This, coupled with their near identical appearance on upper endoscopy, underscores the importance of IHC markers in REFERENCES making a definitive diagnosis. These markers include S-100, CD117 (c-kit), desmin and smooth muscle actin (SMA). GISTs 1. Kang HC, Menias CO, Gaballah AH, Shroff S, Taggart MW, Garg stain positively to CD117 (c-kit); leiomyomas stain positively to N, et al. Beyond the GIST: mesenchymal tumors of the stom- desmin and SMA; and schwannomas stain positively to S-100 ach. Radiographics 2013;33:1673–90. doi:10.1148/rg.336135507. Downloaded from https://academic.oup.com/omcr/article-abstract/2018/3/omy002/4930763 by Ed 'DeepDyve' Gillespie user on 16 March 2018 122 T. Sunkara et al. 2. Shah AS, Rathi PM, Somani VS, Mulani AM. Gastric schwan- ultrasonography. World J Radiol 2010;2:289–97. ISSN 1949. noma: a benign tumor often misdiagnosed as gastrointes- 8470. tinal stromal tumor. Clin Pract 2015;5:775. doi:10.4081/cp. 9. Plesec Thomas P. Gastrointestinal mesenchymal neoplasms 2015.775. other than gastrointestinal stromal tumors: focusing on 3. Wilde BK, Senger J-L, Kanthan R. Gastrointestinal schwan- their molecular aspects. Pathol Res Int 2011;2011:952569. noma: an unusual colonic lesion mimicking adenocarcin- doi:10.4061/2011/952569. 10 pages. oma. Can J Gastroenterol 2010;24:233–6. 10. Vila RDD, Michaelsen MMC, Bonamigo KS, Cerato NL, de 4. Singh A, Mittal A, Garg B, Sood N. Schwannoma of the Garcia VCM, Passos P, et al. Gastrointestinal schwannoma: a stomach: a case report. J Med Case Rep 2016;10:4. DOI10. case report. Arq Bras Cir Dig 2016;29:211. doi:10.1590/0102. 1186/s13256-015-0788-0. 6720201600030019. 5. Voltaggio L, Murray R, Lasota J, Miettinen M. Gastric 11. Li B, Liang T, Wei L, Ma M, Huang Y, Xu H, et al. Endoscopic schwannoma—a clinicopathologic study of 51 cases and interventional treatment for gastric schwannoma: a single- critical review of the literature. Hum Pathol 2012;43:650–9. center experience. Int J Clin Exp Pathol 2014;7:6616–25. www. doi:10.1016/j.humpath.2011.07.006. ijcep.com /ISSN:1936-2625/IJCEP0002097. 6. Yoon W, Paulson K, Mazzara P, Nagori S, Barawi M, Berri R. 12. Hong X, Wu W, Wang M, Liao Q, Zhao Y. Benign gastric Gastric schwannoma: a rare but important differential diag- schwannoma: how long should we follow up to monitor the nosis of a gastric submucosal mass. Case Rep Surg 2012; recurrence? A case report and comprehensive review of lit- 2012:280982. doi:10.1155/2012/280982. 5 pages. erature of 137 cases. Int Surg 2015;100:744–7. DOI:10.9738/ 7. Levy AD, Quiles AM, Miettinen M, Sobin LH. Gastrointestinal INTSURG-D-14-00106.1. schwannomas: CT features with clinicopathologic correlation. 13. Takemura M, Yoshida K, Takii M, Sakurai K, Kanazawa A. Am J Roentgenol 2005;184:797–802. 10.2214/ajr.184.3.01840797. Gastric malignant schwannoma presenting with upper 8. Sakamoto H, Kitano M, Kudo M. Diagnosis of subepithelial gastrointestinal bleeding: a case report. J Med Case Rep 2012; tumors in the upper gastrointestinal tract by endoscopic 6:37. Downloaded from https://academic.oup.com/omcr/article-abstract/2018/3/omy002/4930763 by Ed 'DeepDyve' Gillespie user on 16 March 2018

Journal

Oxford Medical Case Reports – Oxford University Press

Published: Mar 1, 2018

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