Intramural Benign Gastric Tumors

 Remainder are polyps


image Gastrointestinal stromal tumor (GIST) is most common

image Others include lipoma, carcinoid, leiomyoblastoma, lymphangioma, neural tumors





IMAGING




• Upper GI series: Intact mucosa, obtuse or right angles with wall

• GIST: Often large with central necrosis and ulceration of overlying mucosa on CT
image Central area of low attenuation (hemorrhage, necrosis, or cystic formation)

image Most GIST > 2 cm have necrosis ± cavitation

• Lipoma: Most common in antrum
image May prolapse through pylorus into duodenum

image Well-circumscribed areas of uniform fat density = definitive diagnosis


TOP DIFFERENTIAL DIAGNOSES




• Gastric carcinoma

• Gastric metastases and lymphoma

• Ectopic pancreatic tissue

• Pancreatic pseudocyst

• Splenosis

• Gastric ulcer

• Hematoma/seroma


CLINICAL ISSUES




• Carcinoid tumors may be multiple as a result of excess gastrin secretion (Zollinger-Ellison syndrome or atrophic gastritis)


DIAGNOSTIC CHECKLIST




• Lipomas have pathognomonic CT appearance

• GIST has characteristic appearance, but other tumors have overlapping features

• Isolated gastric target lesion is usually GIST

• Multiple target lesions are usually due to metastases

image
(Left) Graphic shows a “generic” intramural gastric mass with intact mucosa and slightly obtuse or right angles at the interface with the gastric wall.


image
(Right) Axial CECT shows a discrete fat-density mass image within the gastric wall with intact, stretched mucosa; diagnostic of a lipoma.

image
(Left) Upper GI series shows a gastric antral mass image with a central ulceration image, typical of a gastric gastrointestinal stromal tumor (GIST). Note the otherwise intact mucosa over the mass, even with preservation of the areae gastricae.


image
(Right) Endoscopic photograph in the same patient shows the submucosal benign gastric GIST image with central ulceration image.


TERMINOLOGY


Definitions




• Benign mass composed of 1 or more tissue elements of gastric wall


IMAGING


General Features




• Best diagnostic clue
image Intramural mass with smooth surface and slightly obtuse borders

• Other general features
image Types of intramural benign gastric tumors
– Gastrointestinal stromal tumor (GIST)

– Lipoma, leiomyoblastoma, lymphangioma, neural tumors


Radiographic Findings




• Radiography
image Mass indenting gastric air shadow, ± calcifications

image Lipoma: Radiolucent shadow

image Hemangioma: Phleboliths (pathognomonic)

• Upper GI series
image Discrete mass, solitary (usually) or multiple

image Smooth surface lesion etched in white (double contrast, profile view)

image Borders form right angle or slightly obtuse angles with adjacent gastric wall (profile view)

image Intraluminal surface of tumor has abrupt, well-defined borders (en face view)

image Usually intact overlying mucosa; normal areae gastricae pattern

image Bull’s-eye or “target” lesions: Central barium-filled crater within mass (ulceration)
– ± giant, cavitated lesions (GIST)

image Pedunculated; may prolapse into duodenum
– Lipomas seem especially likely to do so

image GIST
– Most common; may occur anywhere in GI tract

– Several mm to 30 cm

– Only 1-2% of GISTs are multiple

– ± extragastric extensions (86%): Gastrohepatic ligament, gastrosplenic ligament, lesser sac

image Lipoma, lymphangioma: Tendency to change in size and shape by peristalsis or palpation

image Schwannoma and neurofibroma: Multiple lesions with associated abnormalities


CT Findings




• GIST
image Often large with central necrosis and ulceration of overlying mucosa

image Hypo- or hypervascular, well-circumscribed submucosal mass (arterial phase)

image Peripheral enhancement (92%)
– ± homogeneous enhancement (8%)

image Central area of low attenuation (hemorrhage, necrosis, or cystic formation)
– Most GISTs > 2 cm have necrosis ± cavitation

image Cavitation may communicate with gastric lumen; contain air, air-fluid levels, or oral contrast

image ± calcification

• Lipoma
image Located commonly in gastric antrum
– May prolapse through pylorus into duodenum

image Well-circumscribed areas of uniform fat density (-80 to -120 HU) = definitive diagnosis

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Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Intramural Benign Gastric Tumors

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