Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

QUIZ
Year
: 2005  |  Volume : 15  |  Issue : 1  |  Page : 129--130

Radiological quiz - abdominal imaging


AN Hegde, JA Halankar, SB Desai 
 Department of CT, MRI and DSA , Jaslok Hospital and Research Center, Mumbai, India

Correspondence Address:
S B Desai
Head of Department of CT, MRI and DSA , Jaslok Hospital and Research Center, Mumbai- 400026
India




How to cite this article:
Hegde A N, Halankar J A, Desai S B. Radiological quiz - abdominal imaging.Indian J Radiol Imaging 2005;15:129-130


How to cite this URL:
Hegde A N, Halankar J A, Desai S B. Radiological quiz - abdominal imaging. Indian J Radiol Imaging [serial online] 2005 [cited 2019 Sep 15 ];15:129-130
Available from: http://www.ijri.org/text.asp?2005/15/1/129/29185


Full Text

A 54-year-old male patient was referred with complaints of vague epigastric pain, abdominal fullness, loss of appetite and two episodes of hematemesis since three months. Initially, he ignored the symptoms attributing them to a "gas problem". After a bout of hematemesis he presented himself to a physician. On examination, a firm to hard lump was noted in the epigastrium and right hypochondrium. The patient underwent a contrast enhanced CT for further evaluation. Shown below are a few images of a CT scan obtained after administration of oral and intravenous contrast. What is your diagnosis?

 Radiological Diagnosis



 View Answer

 Gist of Stomach



 Discussion



Contrast enhanced CT scan of the abdomen shows a fairly large mass involving the fundus and body of the stomach along the lesser curvature. The mass has a predominantly extraluminal component, however it is seen to invade the gastric lumen. Areas of ulceration are well seen on the intraluminal surface of the mass [Figure 1] The fat plane between the mass and the pancreas is lost [Figure 2]. Also noted are multiple metastatic lesions in both lobes of the liver and periportal lymphadenopathy. Some of the metastatic deposits show a blood- fluid level suggesting that they may be hypervascular. [Figure 1]. A gastroscopic biopsy was obtained. Histopathology revealed a Gastrointestinal Stromal Tumor of high grade. Gastrointestinal stromal tumors (GISTs) have been reported to constitute about 0.1-3% of GI tumors [1]. GISTs are common in patients between 50 and 60 years of age, and less common in those aged 40 years or younger. The incidence of malignancy is higher in the younger age group. A large number of patients are asymptomatic. Common symptoms are abdominal pain and bleeding, which is present in up to 50% of benign tumors and 85% of malignant tumors. Patients may complain of weight loss, a palpable mass, early satiety, dysphagia and vomiting.

GIST may occur anywhere along the gastrointestinal tract. Approximately 60%-70% of GISTs occur in the stomach, and 20%-30% arise in the small intestine. Less commonly, they may arise in the rectum, colon, esophagus, mesentery, or omentum [2]. Gastrointestinal stromal tumor is a relatively new term that refers to gastrointestinal mesenchymal tumors arising from a common precursor cell. It has been suggested that this precursor cell is either the interstitial cell of Cajal (an intestinal pacemaker cell) or a more primitive stem cell from which both Cajal cells and smooth muscle cells arise. GISTs display spindle cell or epithelioid morphologic characteristics and specific immunohistochemical properties. The most specific and important immunohistochemical marker is the c-kit (CD117) protein, a tyrosine kinase growth factor receptor [3]. In most GISTs, a specific mutation causes a cellular enzyme, known as KIT, to be switched "on" all the time. KIT is an enzyme (called a "tyrosine kinase") responsible for sending growth and survival signals inside the cell. If it is "on," the cell stays alive and grows or proliferates. The overactive, uncontrolled mutant KIT enzyme triggers the runaway growth of GIST tumor cells. This insight into the way GISTs develop has already helped to identify new treatments for this sarcoma. Many tumors previously diagnosed as leiomyomas, leiomyoblastomas, or leiomyosarcomas are now considered GISTs.

Leiomyomas present as a submucosal mass, and may be pedunculated. Leiomyosarcomas arise from the anterior or posterior wall of the stomach and are 12 cm in size on an average. Though they are intramural, large masses are exogastric. Ulceration is common. The liver and regional lymph nodes are the most common sites of metastasis in these patients, with marked necrosis of the liver lesions, which is a common finding. Metastasis to lungs mesentery, omentum [Figure 3], soft- tissue, bone, spleen and ascites may be present [3].

On CT, GISTs present as large extragastric masses, some with calcification or central necrosis [4]. Benign GISTs are usually homogeneous with attenuation values similar to those of muscle [5]Aggressive GISTs are often heterogeneous with central areas of low attenuation reflecting cystic degeneration or necrosis [3],[6].

Signs of malignancy include extrinsic mass effect on the stomach, central necrosis, intratumoral gas, "ulceration that communicates with the stomach by a fistulous tract"[7], adjacent organ invasion and metastatic disease [5],[7]. Other factors that can suggest malignancy and are important in the prognosis are: size, lesions larger than 5 cm are usually leiomyosarcomas rather than leiomyomas[8]. Low-attenuation liver metastases and peritoneal spread may be demonstrated at CT [5]. Hypervascular liver metastases are known[6].

References

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3McLeod AJ , Zornoza J, Shirkhoda A. Leiomyosarcoma: computed tomographic findings, Radiology,1984; 152: 133-136
4Balfe DM, Koehler RE, Karstaedt N , Stanley RJ , Sagel SS. Computed tomography of gastric neoplasms, Radiology,1981;140: 431-436.
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