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GASTROINTESTINAL RADIOLOGY Table of Contents   
Year : 2006  |  Volume : 16  |  Issue : 3  |  Page : 373-376
Gastro intestinal stromal tumor: A case report


From the Super Scans, 31-a, Kaliappa Pillai Street, Tuticorin - 628 001, India

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Keywords: Gist, stomach, ultrasound

How to cite this article:
Shanmugam S, Vijayasekaran D, Marimuthu M G. Gastro intestinal stromal tumor: A case report. Indian J Radiol Imaging 2006;16:373-6

How to cite this URL:
Shanmugam S, Vijayasekaran D, Marimuthu M G. Gastro intestinal stromal tumor: A case report. Indian J Radiol Imaging [serial online] 2006 [cited 2020 Aug 12];16:373-6. Available from: http://www.ijri.org/text.asp?2006/16/3/373/29022

   Introduction Top


Gastro Intestinal Stromal Tumors (GISTs) are a subset of GI mesenchymal tumors of varying differentiation. Previously, these tumors were classified as GI leiomyomas, leiomyosarcomas, leiomyoblastomas, or schwannomas as a result of their histological findings and apparent origin in the muscularis propria layer of the intestinal wall. With the advent of immunohistochemical staining techniques and ultra structural evaluation, GISTs now are recognized as a distinct group of mesenchymal tumors. GI stromal tumors express c-kit protein also known as CD 117, and is considered as highly specific marker that differentiates GIST from other mesenchymal tumors such as leiomyomas [1].


   Case report Top


A 58 year old female presented with history of fever, cough and vomiting for 2 days. She gave past history of two episodes of melena. She was a known hypertensive on medication. Her blood pressure was under control. On clinical examination she was found to be anemic. Her abdomen was soft and a vague mass was palpable in epigastrium. Her routine blood investigations were within normal limits except for low hemoglobin level.

2D ultrasound examination of abdomen with 3Mhz - 8Mhz broad band convex transducer revealed well defined hypoechoic solid mass lesion measuring 6cm X 5cm arising from the posterior wall of the stomach [Figure - 1]. Scanning with 4Mhz - 13Mhz linear transducer revealed hypoechoic solid mass in the submucosal location of posterior gastric wall. [Figure - 2].

The mucosal surface in the region of the mass was intact and regular. Color Doppler examination showed few vessels in the periphery of the mass. No evidence of arterio-venous shunting was seen [Figure - 3] 3D Ultrasound examination showed well defined solid mass in the posterior gastric wall, projecting into the gastric lumen which was distended with water [Figure - 4]. 3D ultrasound in color Doppler angiography mode revealed more number of blood vessels inside the mass compared to 2D color Doppler. [Figure - 5] Surface mode in 3D ultrasound revealed a smooth surfaced mass projecting intra luminally with a small ulcer in the summit of its surface [Figure - 6]. 3D ultrasound surface mode image with sepia coloring resembled exactly the gastroscopic appearance of the same lesion [Figure - 7]. Biopsy of the above mass was not done during gastroscopic examination for fear of uncontrollable bleeding.

CT Scan of abdomen was done to identify the presence of any metastasis missed during Ultrasound examination. CT Scan again confirmed the mass in posterior gastric wall, small ulcer in the mucosal surface of the above mass and thin rim of calcification in the periphery in one portion of the mass [Figure - 8].

Under general anesthesia laparotomy was done through upper midline incision. Mass was seen arising from the posterior wall of body of stomach. Gastrostomy was done through anterior gastric wall. Excision of the mass measuring 6cm X 5cm with small ulceration on its surface was done.

Histo Pathological examination of the mass was reported as follows; "shows wall of the stomach with a tumor arising from muscularis propria and extending into the serosa composed of interlacing fascicles of spindle shaped cells oval to elongated nuclei exhibiting mild pleomorphism and eosinophilic cytoplasm, mitotic figures at the rate of 2-3/50 HPFs. There is focal hyalinization and myxoid change with mild infiltrates of lymphocytes, plasma cells, eosinophils. Immunohistochemistry: Cells are positive of CD117 and CD34 and are negative for SMA and S1000. Impression- Gastrointestinal stromal tumor , stomach. In view of the size of mitotic rate, this may be aggressive in behavior".


   Discussion Top


Although morphologically similar to other benign and malignant smooth muscle and neural stromal tumors, GIST constitutes a distinct group of rare gastrointestinal tract tumors that originate from the interstitial cells of Cajal. The latter are regulators of gut peristalsis and normally express CD117, which is a product of the c-kit proto-oncogene that encodes a tyrosine kinase receptor, which regulates cellular proliferation in GISTs [2]

GISTs arise from the muscularis mucosa or muscularis propria layers and most exhibit an endophytic growth pattern, growing within the bowel lumen. In up to one third of patients the tumor invades an adjacent organ. The vast majority of GISTs (up to 70%) arise in the stomach, with 20-30% originating in the small intestine and the remainder 10% occurring in the oesophagus, colon and rectum [3].

Most of GISTs are small and asymptomatic and are discovered incidentally during evaluation for unrelated problems. When the lesion grows over 2cm in size, ulceration may occur. Symptoms like epigastric pain and gastro intestinal bleeding become more common then. Occasionally the lesion may be pedunculated and may obstruct the pylorus or duodenum. Spontaneous rupture of large mass into gastric lumen has also been reported [4].

The aim of imaging is to locate GIST lesions, evaluate local invasion, and detect distant metastases. In barium studies of the stomach, GISTs have the classic features of sub mucosal masses, similar to those of leiomyomas and leiomyosarcomas [5]. They have a smooth mucosal surface when coated with barium, and the overlying mucosal surface is generally intact with the exception of focal areas of ulceration, which can be seen in 60% of cases [5].

On sonograms, larger GISTs appear as complex masses with cystic and solid components, which are consistent with their tendency to necrose. Ultrasound examination with high resolution transducer confirms the intramural mass in sub mucosal location. 3D ultrasound demonstrates smooth mucosal surface and the ulceration, if present. Appropriate reformation of 3D data can produce images resembling the gastroscopic appearance.

Endoscopic ultrasonography can be valuable in the evaluation of GISTs. The tumors appear as hypoechoic masses that are contiguous with the fourth hypoechoic layer of the GI wall, which corresponds to the muscularis propria. Characteristics associated with malignancy include tumor size greater than 4 cm, an irregular extraluminal border, echogenic foci, and cystic spaces.

CT is ideal in defining the endoluminal and exophytic extent of tumor. Smaller GISTs appear as smooth, sharply defined intramural masses with homogenous attenuation Contrast enhancement may be rim like or uniform. Occasionally, dense focal calcifications are present. Larger GISTs with necrosis appear as heterogeneous masses with enhancing borders of variable thickness and irregular central areas of fluid, air, or oral contrast attenuation that reflect necrosis. Overlying mucosal ulcerations and extension into nearby structures may be present. CT is also sensitive for the detection of metastatic liver, peritoneal, lung, and bone lesions. The diagnosis of GIST can be suggested in the presence of a large, complex, intestinal mass with liver lesions but without significant lymphadenopathy. CT scanning has good sensitivity for the detection of GISTs, and it can show abnormalities in 87% of cases [6].

Magnetic resonance (MR) imaging features of gastric GISTs are variable. The degree of necrosis and hemorrhage greatly affects the signal-intensity pattern. The solid portions of tumor tend to be isointense relative to skeletal muscle on T1-weighted images and hyperintense on T2-weighted images, and enhance after administration of gadolinium. Areas of hemorrhage within the tumor will vary from high to low signal intensity on both T1- and T2-weighted images, depending on the age of the hemorrhage [7].

Unfortunately, imaging findings are nonspecific to differentiate between Leiomyoma and GIST. Imaging studies cannot reliably distinguish benign from malignant GIST unless there is obvious metastases or local extension. However a favorable prognosis is associated with tumor size less than 5cm and lack of infiltration into adjacent organs.

Both tumor size mitotic activity and have been identified as the most important factors predicting malignant behavior [8]. The number of mitotic figures present can be used to histologically grade GISTs. In general, GISTs with less than 1 mitotic figure per 50 high-powered fields (HPFs) are correlated with benign behavior. A finding of 1-5 mitoses per 10 HPFs suggests potential malignancy. A finding of more than 5 per 10 HPFs indicates malignancy. A finding of more than 10 per 10 HPFs denotes high-grade malignancy [6]

The diagnosis of GIST should be considered whenever intramural mass in sub mucosal location is seen in stomach or small intestine. Although GIST can be suggested histologically, the diagnosis must be made immunochemically with cells positive of CD 117.

 
   References Top

1.Miettinen M, Sarlomo-Rikala M, Lasota J: Gastrointestinal stromal tumors: recent advances in understanding of their biology. Hum Pathol. 1999, 30:1213-1220.  Back to cited text no. 1    
2.Sincar K, Hewlett BR, Huizinga JD, Chorneyko K, Berezin I, Riddell RH: Intestinal cells of Cajal as precursors of gastrointestinal stromal tumors. Am J Surg Pathol. 1999, 23:377-389  Back to cited text no. 2    
3.DeMatteo RP, Lewis JJ, Leung D, Mudan SS, Woodriff JM, Brennan MF: Two hundred gastro-intestinal stromal tumors: recurrence patterns and prognostic factors for survival. Ann Surg. 2000, 231:51-58.  Back to cited text no. 3    
4.Rajiv M Mehta, Vayoth O Sudheer, Anil K John, Raghavan R Nandakumar, Puneet S Dhar, Surendran Sudhindran and Vallath Balakrishna: Spontaneous rupture of giant gastric stromal tumor into gastric lumen. World Journal of Surgical Oncology 2005, 3:11,1477-1478  Back to cited text no. 4    
5.Nauert TC, Zornoza J, Ordonez N. Gastric leiomyosarcoma. AJR Am J Roentgenol. 1982; 139:291-297.  Back to cited text no. 5    
6.Pidhorecky I, Cheney RT, Kraybill WG, Gibbs JF: Gastrointestinal stromal tumors: current diagnosis, biologic behavior, and management. Ann Surg Oncol 2000 Oct; 7(9): 705-712.  Back to cited text no. 6    
7.Hasegawa S, Semelka RC, Noone TC, et al. Gastric stromal sarcomas: correlation of MR imaging and histopathologic findings in nine patients. Radiology 1998; 208:591-595.  Back to cited text no. 7  [PUBMED]  
8.Miettinen M, El-Rifai W, Sobin LH, Lasota J: Evaluation of malignancy and prognosis of gastrointestinal stromal tumors: a review. Hum Pathol. 2002, 33:478-483.  Back to cited text no. 8    

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Correspondence Address:
S Shanmugam
Super Scans, Ss Centre, 31-a, Kaliappa Pillai Street, Tuticorin - 628 001
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-3026.29022

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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8]

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