Stomach GIST – Radiology Cases

Case contribution: Dr Radhiana Hassan

Clinical:

A 75 years old man
Underlying HPT, dyslipidaemia
History of open left hernioplasty 5 years ago
Presented with abdominal swelling for one week
Associated with abdominal pain, colicky in nature, no constitutional symptoms, no altered bowel habit, no fever
Clinical examination shows a left hypochondriac mass, tender, no splenomegaly

Radiograph findings:

Ultrasound findings:

There is a large heterogenous solid cystic mass occupying the left hypochondriac area.
The cystic components have internal septations within them.
No internal calcification seen.
There is scanty vascularity detected on colour Doppler examination.
The mass is seen adjacent to the tail of the pancreas and pushing the left kidney posteriorly. Otherwise the pancreas is normal.
The mass is also seen touching the posterior margin of the left liver lobe.

CT scan findings:

A large heterogeneous multi-lobulated peripherally enhancing mass (mean HU 21) is seen in the left hypochondrium and lumbar region.
This mass collectively measures about 9.8 cm x 14.7 cm x 19.2 cm (AP x W x CC).
Large areas of central hypodensity are noted, most likely central necrosis.
The superior part of the mass appears more cystic with HU of 18 – 30.
Multiple vessels are also seen in between these structures, particularly at the anteroinferior aspect (red arrows).
No fat component or calcification is seen within this mass. No fluid-fluid level is seen.
The mass show claw-sign to the adjacent stomach, in which possible it arise from the wall of the stomach. The stomach is compressed posteriorly by the mass.
The mass is also seen displacing the pancreas, splenic vein and left kidney posteriorly.
The mass also displaces the bowel loops medially and inferiorly. Clear fat plane with adjacent bowel loops is seen.
No bowel dilatation or bowel wall thickening is identified

Progress of patient:

Intraoperative findings:

Huge solid cystic mass occupying the lesser sac, pushing the stomach anteriorly and the transverse colon inferiorly
Mass cystic in nature and highly vascularized
Tumour densely infiltrate the posterior part of stomach at the greater curvature and tail of pancreas
Multiple mesenteric and omentum nodules seen
Semi-emergency laparotomy, sleeve gastrectomy and distal pancreatotomy done

HPE findings:

Cystic tumour: gastrointestinal stromal tumour (GIST) of the stomach. TNM stage pT4pN0pM1.
Tumour perforation is present.
No lymphovascular or perineural invasion noted. No evidence of nodal involvement.
Tumour deposit on the splenic capsule
Metastatic GIST to omentum and mesenteric nodule
Falciform ligament: no evidence of malignancy/metastasis

Discussion:

Gastrointestinal stromal tumors (GISTs) are soft tissue sarcomas that can be located in any part of the digestive system.
Their most common sites are the stomach and small intestine.
The peak age for GIST of the stomach is around 60 years and a slight male preponderance is reported.
Symptoms at presentation usually include bleeding, abdominal pain or abdominal mass.
Endoscopically, they typically appear as a submucosal mass with or without ulceration
on CT scans an extragastric mass is usually seen. They are rounded with frequent hemorrhage. Larger tumors may also demonstrate necrosis and cystic change. Size is variable, ranging from 1 to 30 cm.
Typically the mass is of soft tissue density with central areas of lower density when necrosis is present (usually in larger tumors) that occasionally appear as fluid-fluid levels.
Enhancement is typically peripheral (due to central necrosis).
Calcification is uncommon (3%).
Metastases (distant, peritoneal, omental) or direct invasion into adjacent organs may be seen in more aggressive lesions. Lymph node enlargement is not a feature.
The diagnosis of malignant GIST requires histopathologic analysis, but certain characteristics suggest malignancy, which develops in 10-30% of these lesions. These include exogastric growth, diameter >5 cm, central necrosis, and extension to other organs.