MAMC Journal of Medical Sciences

CASE REPORT
Year
: 2020  |  Volume : 6  |  Issue : 2  |  Page : 128--134

Cystic Gastrointestinal Tumors: An Unusual Imaging Appearance − A Case Series


Radhika Batra1, Surabhi Gupta1, Anjali Prakash1, Lalendra Upreti2, Sapna Singh1,  
1 Department of Radiology, Maulana Azad Medical College and Lok Nayak Hospital, New Delhi, India
2 Department of Radiology, Rajiv Gandhi Super Speciality Hospital, New Delhi, India

Correspondence Address:
MBBS Surabhi Gupta
DNB Radiology, C-152 (Second Floor), Sarvodaya Enclave, New Delhi-110017
India

Abstract

Gastrointestinal stromal tumors (GISTs) are commonly seen mesenchymal tumors of stomach and digestive tract. Morphologically they show similarities to other tumor types and were previously misclassified as leiomyomas, leiomyoblastomas, or leiomyosarcomas. GISTs are typically solid tumors with larger tumors showing areas of necrosis and rarely present with predominantly cystic changes. Here we report three cases of GISTs with predominant cystic component. Cystic GISTs although rare, should be considered as part of differential diagnosis for large intra-abdominal cystic lesions. Immunohistochemistry is critical for final diagnosis.



How to cite this article:
Batra R, Gupta S, Prakash A, Upreti L, Singh S. Cystic Gastrointestinal Tumors: An Unusual Imaging Appearance − A Case Series.MAMC J Med Sci 2020;6:128-134


How to cite this URL:
Batra R, Gupta S, Prakash A, Upreti L, Singh S. Cystic Gastrointestinal Tumors: An Unusual Imaging Appearance − A Case Series. MAMC J Med Sci [serial online] 2020 [cited 2020 Oct 24 ];6:128-134
Available from: https://www.mamcjms.in/text.asp?2020/6/2/128/293885


Full Text



 Introduction



Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the digestive tract. GISTs account for 60% of all gastric stromal tumors and only less than 5% of all gastrointestinal tract (GIT) tumors.[1] They arise from the interstitial cells of Cajal (ICC) located in the gastrointestinal mesenchyme.[2] GISTs express tyrosine protein kinase (KIT) protein, cluster of differentiation (CD) 117 on immunohistochemistry. Morphologically they appear similar to other submucosal tumors and were previously misclassified as leiomyomas, leiomyoblastomas, and leiomyosarcomas. GISTs can arise anywhere in the GIT, including the omentum, mesentry, and retroperitoneum. GISTs originating from extraintestinal sites have also been reported.[3],[4],[5] The radiologic features of GISTs vary depending upon their size and anatomic location. In general, most common and usual feature of GIST seen on cross-sectional imaging is a well-defined exophytic heterogenous mass with intratumoral hemorrhage and necrosis. Predominantly cystic GISTs are rare in occurrence.[6],[7] Since the discovery of KIT (CD 117) in 1998, GISTs were classified as a distinct entity.[8] We report few cases of GISTs with predominantly cystic changes.

 Case Reports



Case 1

A 50-year old female presented with a large abdominal mass associated with abdominal distension and dull aching pain in abdomen. Physical examination revealed a large palpable mass, measuring approximately 15 × 22 cms, located in the left upper and lower quadrant of abdomen reaching up to midline. Laboratory findings including blood biochemistry, routine blood tests, coagulation profile were within normal range. Clinically the mass was suspected to have an ovarian origin. The tumor markers CA 125 (33.4kU/L, normal range − 0-35kU/L) and CEA (2.9ng/ml, normal range − <3ng/ml) were not elevated. Ultrasound of the abdomen [Figure 1]A, B revealed a large well-defined cystic lesion in left side of abdomen with a small peripheral solid component and septations within. Bilateral ovaries and uterus were seen separately from the lesion. As the organ of origin was unclear, subsequent contrast enhanced abdominal CT [Figure 2]A–D of the patient was performed which revealed a large, predominantly cystic, intraperitoneal mass lesion with no evidence of calcification, seen arising from the anterior wall of the antropyloric region of stomach. The lesion measured 12 cm x 15.6 cm x 20.3 cm in maximum dimensions and showed poorly defined heterogeneously enhancing solid component along its posterior wall and multiple enhancing septae within. The gastric mucosa at stomach-lesion interface appeared intact suggesting submucosal origin of the mass. MR imaging [Figure 3]A–D revealed marked hyperintensity on T2WI, compatible with its cystic nature, in addition to clear demonstration of uterus and bilateral ovaries which were separate from the mass. Upper GI endoscopy showed a mass lesion in gastric antropyloric region with smooth overlying mucosa. Surgical laparotomy confirmed the imaging findings and total cyst excision with partial gastric resection was performed. The resected tumor measured nearly 20 cm in maximum dimension. Grossly [Figure 4]A, it was a cystic tumor filled with serous fluid, with a smooth outer surface, a small solid component, and membranous septa projecting in the lumen. Post-operative histopathology [Figure 4]B showed spindle cell pattern on haematoxylin and eosin (H&E) slides and displayed positivity for CD 117 and discovered on GIST-1 (DOG-1) markers.{Figure 1}{Figure 2}{Figure 3}{Figure 4}

Case 2

A 35-year old male presented with complaints of abdominal pain and abdominal distension for 3 months associated with loss of weight and appetite. Physical examination revealed a large, hard palpable mass of approximately 25 × 20 cm, located in central and lower abdomen. Laboratory findings, such as routine blood tests, blood biochemistry, and coagulation profile were normal. The initial barium meal examination [Figure 5]A, B revealed a large soft tissue density in central and lower abdomen on plain film, causing displacement and mass effect on the third segment of duodenum and proximal jejunal loops on subsequent images taken after oral contrast administration. There was resultant faint opacification of third and fourth segments of duodenum and proximal jejunal loops. No evidence of bowel obstruction was noted. Ultrasound abdomen [Figure 6]A–C of the patient showed a large intraperitoneal cystic lesion with homogenous internal echoes and small peripheral solid component having foci of internal vascularity on color doppler. Contrast-enhanced CT abdomen [Figure 7]A–C of the patient revealed a large cystic lesion, measuring 13.6 cm x 24.6 cm x 26 cm in maximum dimensions with peripheral enhancing solid component in the abdomen. No evidence of calcification was noted within the lesion. The mass showed enhancement of the peripheral solid component and was suspected to arise from distal duodenal/proximal jejunal loops of small bowel. It was seen to abut and compress the transverse colon and ascending colon and displace small bowel loops to the periphery. Branches of superior mesenteric artery (SMA) were seen traversing through the mass, with celiac axis and SMA being displaced to the left side. The mass was seen to compress the inferior vena cava (IVC), superior mesenteric vein (SMV), and splenic vein. The mass lesion showed loss of planes with the pancreatic head and uncinate process. Few retroperitoneal lymph nodes, predominantly in para-aortic location were noted. Findings on surgical laparotomy were consistent with imaging findings and total cyst excision with regional lymphadenectomy was performed. Post-operative histopathology [Figure 8]A of tumor cells showed spindle- or stellate-shaped body of tumor cells with thin perinuclear cytoplasm on H&E staining and positivity for CD 117 and discovered on GIST-1 (DOG-1) markers on immunohistochemistry.{Figure 5}{Figure 6}{Figure 7}{Figure 8}

Case 3

A 45- year old female presented to the outpatient department with complaints of lump in abdomen associated with dull aching abdominal pain and feeling of fullness. On physical examination, a palpable mass, approximately 12 × 15 cms in size, was found in left upper and central abdominal compartment. Routine blood investigations were within normal limits. Barium meal examination [Figure 9]A, B for the patient revealed a well- defined round soft tissue density in relation to greater curvature of stomach on plain film, with a filling defect in distal body and antropyloric region of stomach on images taken after oral contrast. No upstream gastric obstruction was noted. Contrast-enhanced CT abdomen [Figure 10]A–C, [Figure 11]A, B of the patient revealed a large cystic mass, measuring 11.4 cm x14.8 cm x 16.9 cm in maximum dimensions, seen arising from the greater curvature of stomach in the distal body and antropyloric region. The mass shows enhancing solid component in its anterosuperior aspect, causing focal luminal attenuation in the antropyloric region. An initial diagnosis of gastric GIST was considered. Exploratory laparotomy findings were consistent with the imaging findings and total cyst excision was performed. Histopathological work-up confirmed the diagnosis of Gastric GIST, with tumor cells being positive for CD 117 and DOG-1 tumor markers.{Figure 9}{Figure 10}{Figure 11}

 Discussion



GISTs have an annual incidence of 4 per million[9] making them one of the rare neoplasms of abdomen. Previously GISTs were believed to originate from the smooth muscle cells of GIT and were therefore classified in the same bracket as leiomyomas, leiomyoblastomas, and leiomyosarcomas and even as schwannomas or malignant peripheral nerve sheath tumors. However, GISTs are now known to arise from the pacemaker cell, such as the interstitial cells of Cajal located in the submucosa and muscularis propria of the gastrointestinal tract and hence can occur in the esophagus, stomach, small intestine, and colon.[1] Extraintestinal GISTs originating from uterus, gallbladder, and pancreas have also been reported recently.[3],[4],[5] All GISTs are typically positive for cell markers similar to normal interstitial cell of Cajal, Cluster of differentiation 117 (CD 117) antigen tyrosine protein kinase (KIT), a protooncogene product which is positive in 90% of GISTs. Discovered on GIST-1 (DOG-1), another sensitive marker is positive in 95% cases and cluster of differentiation 34 (CD 34), a commonly expressed human progenitor cell antigen is positive in 50-80% of the cases.[10]

Complete resection of the tumor with negative resection margins is the treatment of choice for primary non-metastatic tumor.

An unusual feature in our cases was predominantly cystic nature of the mass lesions. Appearance of GISTs varies with tumor size and location but are most commonly seen as solid, heterogeneously enhancing neoplasms with a small submucosal component and large exophytic component. Non-enhancing areas representative of necrosis are seen in larger tumors. Calcification is uncommon. GISTs showing predominantly cystic changes are rare in occurrence. GISTs with cystic changes are more frequently seen in high-grade malignancies. Aggressive tumor growth results in inadequate blood supply to the tumor leading to hemorrhage, necrosis, and cystic degeneration within the tumor.[11]Whenever we encounter a cystic abdominal mass on cross-sectional imaging such as CT and MRI, we must consider gastric or bowel duplication cysts, cystic mesothelioma, cystic lymphangioma, cystic mucinous retroperitoneal tumors, cystic pancreatic tumors, pseudocysts of the pancreas or peritoneum, cystic teratoma, and GIST as differentials.[12],[13],[14] In all our cases, post-operative histopathological examination together with the immunohistiochemical profile (positive for CD 117 and DOG-1) of the tumor cells were consistent with a diagnosis of GIST.

 Conclusion



Our cases highlight the fact that GISTs with rapid growth can present as predominantly cystic abdominal mass, and need to be considered as differential diagnosis of intra-abdominal cystic lesions with unknown or undefined origin. Immunohistochemistry is essential to clinch the final diagnosis in such cases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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