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 » Introduction
 » Case Report
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  Table of Contents  
Year : 2020  |  Volume : 57  |  Issue : 3  |  Page : 334-336

Primary retroperitoneal GIST: Case report and review of literature

1 Department of Surgical Oncology, Tata Memorial Hospital, Mumbai, Maharashtra, India
2 Department of Pathology, Tata Memorial Hospital, Mumbai, Maharashtra, India

Date of Submission22-Aug-2018
Date of Decision11-Nov-2018
Date of Acceptance03-Dec-2018
Date of Web Publication08-Jul-2020

Correspondence Address:
Krunal H Khobragade
Department of Surgical Oncology, Tata Memorial Hospital, Mumbai, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijc.IJC_556_18

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 » Abstract 

Extraintestinal gastrointestinal stromal tumors (EGISTs) are mesenchymal tumor with no connection to tubular gastrointestinal system. They commonly arise from omentum and mesentry. Retroperitoneum is a rare primary site. We herein report a case of a 33 year old woman who underwent upfront surgery for primary retroperitoneal gastrointestinal stromal tumor and is now disease-free on adjuvant Imatinib.

Keywords: Extraintestinal gastrointestinal stromal tumors, retroperitoneum, Imatinib

How to cite this article:
Khobragade KH, Patkar S, Goel M, Sahay A. Primary retroperitoneal GIST: Case report and review of literature. Indian J Cancer 2020;57:334-6

How to cite this URL:
Khobragade KH, Patkar S, Goel M, Sahay A. Primary retroperitoneal GIST: Case report and review of literature. Indian J Cancer [serial online] 2020 [cited 2020 Oct 1];57:334-6. Available from:

 » Introduction Top

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. Approximately, 60% arise in the stomach and 30% arise in the small bowel; the other 10% arise in the esophagus, colon, rectum, gallbladder, appendix, omentum, mesentery, retroperitoneum, and pelvis.[1] GISTs that are not connected to the walls or serosal surfaces of gastrointestinal tubular organs are called extraintestinal GIST (EGIST) and are rare.[2] Most of the EGISTs originate from the omentum and mesentry; however, other primary sites, such as pancreas, hepatobiliary tree, uterus, and vagina have been reported.[3-5] EGISTs of the retroperitoneum are very rare and not much is known about their clinicopathological behavior. Herein, we present a case of EGIST in a 33-year-old woman located in the retroperitoneum with no connection to gastrointestinal system.

 » Case Report Top

A 33-year-old woman presented to our hospital with pain in right side of abdomen and loss of appetite for 1 year. On examination, she had a 15 × 12 cm hard palpable lump in right hypochondrium and right lumbar region. Abdominal computed tomography (CT) scan showed a 13 × 10 cm heterogenously enhancing retroperitoneal mass with displacement of right colon, duodenum, and right kidney [Figure 1]. The patient underwent ultrasonography-guided biopsy from the mass which showed malignant tumor in a myxoid stroma. Patient underwent surgical exploration. Intraoperatively, there was a 20 cm × 18 cm retroperitoneal mass with involvement of right renal vein. Duodenum and head of pancreas were pushed medially by tumor and there was no communication with gastrointestinal system. The tumor was excised completely (R0 resection) with intact capsule along with right nephrectomy. Postoperative course was uneventful. Pathological examination revealed a 17 × 15 cm encapsulated retroperitoneal tumor with negative margins. The cut surface of tumor was yellowish with solid-cystic areas and myxoid and friable in consistency. On microscopic examination [Figure 2], an encapsulated tumor was seen with spindle and epithelioid cells arranged in sheets and short fascicles. The mitotic count was 1-2/10hpf. Mib-1 labeling index was 5–7% in the highest proliferating areas. On immunohistochemistry, tumor cells were positive for S100 and c-kit while negative for DOG1, SMA, CD34, HMB45, and Melan-A [Figure 3]. SOX 10 was not performed. The nephrectomy specimen did not reveal any malignant involvement. She is on adjuvant imatinib in view of intermediate risk and is disease free at 18 month interval.
Figure 1: CT scan showing right retroperitoneal mass

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Figure 2: Microscopic image showing spindle cells in sheets

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Figure 3: Immunohistochemistry showing positivity for c-kit

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 » Discussion Top

GISTs are potentially malignant tumors and the commonest mesenchymal tumors of the gastrointestinal tract. The age-adjusted incidence of clinical GIST was 0.8 per 100,000 per year.[6] The term gastrointestinal stromal tumor was initially coined as a purely descriptive term by Mazur and Clark in 1983 to define intraabdominal tumors that were not carcinomas (i.e., nonepithelial tumors).[7] The cell of origin for GIST is interstitial cell of Cajal or related stem cell precursor. In 1998, Hirota et al. discovered a gain of function mutation in the protooncogene KIT in GIST.[8] Approximately, 75% of GISTs bear activating mutations in KIT, with PDGFRα mutated in another 10% and the remaining group of “wild type” GISTs has continued to shrink because alterations have been discovered in BRAF, SDH, and NF1 in other patients.[9] Approximately, 95% of GISTs are positive for KIT (CD117) and/or discovered on GIST-1 (DOG1), and 70% are found to be positive for CD34 by immunohistochemistry. The tumor extent is identified on cross-sectional imaging like CT or magnetic resonance imaging.[10]

The term “EGIST” was coined by Reith et al. in 2000 for tumors which occur in soft tissues of the abdomen and described them as histologically and immunophenotypically similar to GISTs.[2] EGIST account for less than 10% of stromal tumors. Most EGISTs arise from omentum, mesentery, retroperitoneum, and other undefined abdominal sites.[11] Till date, only 173 cases of primary retroperitoneal GIST have been reported.[12-14] However, in most cases the location of retroperitoneal GIST is not further specified. In the largest series of 112 cases of retroperitoneal GISTs, 35 were identified to have gastrointestinal communication and in 35 cases the primary site was unspecified.[14] Peripancreatic was the largest group when site was specified in this series. Retroperitoneal GISTs are usually advanced and large in size >10 cm. The two main patterns of histology in retroperitoneal EGISTs are spindle cell and epithelioid.[15] Most retroperitoneal GISTs are c-kit (95%) and DOG 1 (93%) positive.[14] On imaging, they may be confused with lymphomas or other mesenchymal tumors at the same location; however, the differentiation from EGISTs on imaging may be made on the basis of absence of necrosis, cystic changes, hemorrhage, and calcification within lymphomatous neoplasms.[16] The current form of management for these tumors includes surgery and debulking of masses whenever possible along with adjacent tissues which are infiltrated. Imatinib can be used as neoadjuvant therapy if initial surgery involves multiorgan resection. Retroperitoneal GISTs have poorer outcomes compared to classical GISTs, with median survival of 14 months and few surviving beyond 5 years. Operability and mitotic rate have been identified as important prognostic factors.[14]

 » Conclusion Top

Due to rarity of primary retroperitoneal GIST, it is important to study their imaging, histology, and clinical behavior.

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Conflicts of interest

There are no conflicts of interest.

 » References Top

Miettinen M, Lasota J. Gastrointestinal stromal tumors: Pathology and prognosis at different sites. Semin Diagn Pathol 2006;23:70-83.  Back to cited text no. 1
Reith JD, Goldblum JR, Lyles RH, Weiss SW. Extragastrointestinal (soft tissue) stromal tumors: An analysis of 48 cases with emphasis on histologic predictors of outcome. Mod Pathol 2000;13:577-85.  Back to cited text no. 2
Iqbal N, Sharma A, Iqbal N. Clinicopathological and treatment analysis of 13 extragastrointestinal stromal tumors of mesentery and retroperitoneum. Ann. Gastroenterol 2015;28:105-8.  Back to cited text no. 3
Tombatore C, Palmucci S, Angelico G, Vasquez E, Petrillo G, Puelo S, et al. Extragastrointestinal stromal tumor of lesser omentum: A challenging radiological and histological diagnosis. Clin Imaging 2015;33:1123-7.  Back to cited text no. 4
Padhi S, Sarangi R, Mallick S. Pancreatic extragastrointestinal stromal tumors, interstitial Cajal like cells and telocytes. JOP 2013;14:1-14.  Back to cited text no. 5
Ma GL, Murphy JD, Martinez ME, Sicklick JK. Epidemiology of gastrointestinal stromal tumors in the era of histology codes: Results of a population-based study. Cancer Epidemiol Biomarkers Prev 2015;24:298-302.  Back to cited text no. 6
Mazur MT, Clark HB. Gastric stromal tumors. Reappraisal of histogenesis. Am J Surg Pathol 1983;7:507-19.  Back to cited text no. 7
Hirota S, Isozaki K, Moriyama Y, Hashimoto K, Nishida T, Ishiguro S, et al. Gain of function mutations of c-kit in human gastrointestinal stromal tumors. Science 1998;279:577-80.  Back to cited text no. 8
Corless CL, Heinrich MC. Molecular pathobiology of gastrointestinal stromal sarcomas. Annu Rev Pathol 2008;3:557-86.  Back to cited text no. 9
Gong J, Kang W, Zhu J, Xu J. CT and MR imaging of gastrointestinal stromal tumor of stomach: A pictorial review. Quant Imaging Med Surg 2012;2:274-9.  Back to cited text no. 10
Dubey U, Rumpa D, Agrawal A, Pantola C, Verma N. Malignant extragastrointestinal stromal tumours: What are the prognostic features to depend upon? J Clin Diagn Res 2011;52:369-71.  Back to cited text no. 11
Yi JH, Park BB, Kang JH, Hwang IG, Shin DB, Sym SJ, et al. Retrospective analysis of extragastrointestinalstromal tumors. World J Gastroenterol 2015;21:1845-50.  Back to cited text no. 12
Laroia ST, Yadava T, Rastogi A, Sarin S. Malignant retroperitoneal extra-gastrointestinal stromal tumor: A unique entity. World J Oncol 2016;7:45-50.  Back to cited text no. 13
Miettinen M, Felisiak-Golabek A, Wang Z, Inaguma S, Lasota J. GIST manifesting as a retroperitoneal tumor: Clinicopathologic, immunohistochemical, and molecular genetic study of 112 cases. Am J Surg Pathol 2017;41:577-85.  Back to cited text no. 14
Casella C, Villanacci V, D'Adda F, Codazzi M, Salerni B. Primary extra-gastrointestinal stromal tumor of retroperitoneum. Clin Med Insights Oncol 2012;6:189-97.  Back to cited text no. 15
Ghanem N, Altehoefer C, Furtwangler A, Winterer J, Schafer O, Springer O, et al. Computed tomographyin gastrointestinal stromal tumors. Eur Radiol 2003;13:1669-78.  Back to cited text no. 16


  [Figure 1], [Figure 2], [Figure 3]


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