Malignant Gastric Tumors

Gastric Adenocarcinoma

Adenocarcinoma accounts for 95% of all gastric cancers and typically presents as focal or segmental wall thickening (>1 cm) or as a discrete mass. The thickening may be asymmetric or circumferential, with irregular margins. Ulceration is common, and advanced cases may show perigastric fat infiltration, lymphadenopathy, or distant metastases [5, 6].

On contrast-enhanced CT, adenocarcinoma often shows heterogeneous enhancement in the arterial phase, with tumor staining in the venous phase. Mucinous adenocarcinoma may exhibit punctate or miliary calcifications within the tumor [3].

MDCT is highly accurate for staging, with a sensitivity > 90% for advanced carcinomas. However, early gastric cancers (limited to mucosa or submucosa) are more challenging to detect, with a sensitivity of 18% for depressed lesions [5].

Fig 1: A 73-year-old female with stage IV gastric adenocarcinoma. Axial (a) and coronal (b) CT scans show a solid heterogeneous mass (arrow) in the gastric body, measuring 8 x 5 cm, protruding into the gastric lumen. Hepatic and nodal metastases are also present. An EGD image (c) shows the gastric body lesion on the greater curvature. References: Department of Imaging and Department of Gastroenterology, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Gastric Lymphoma

Gastric lymphoma represents 25% of extranodal lymphomas and is characterized by diffuse or segmental wall thickening (2-4 cm) with a significant lateral tumor extension. The thickening is usually homogeneous, but areas of low attenuation may be seen due to necrosis. Lymphadenopathy extending below the renal hila is a key feature [3].

Lymphoma tends to enhance less intensely than adenocarcinoma, with a more uniform appearance. Perigastric fat planes are often preserved, even in advanced cases [6].

CT can detect complications such as perforation, fistulization, or extragastric extension, which are more common in lymphoma than in adenocarcinoma [6].

Fig 2: A 75-year-old male with diffuse large B-cell lymphoma in the stomach. Axial (a) and coronal (b) CT scans reveal a nodular lesion in the gastric antrum (arrow) with endoluminal polypoid protrusion, measuring 45 mm. An EGD image (c) displays the gastric antrum with a subepithelial lesion and endoluminal protrusion. References: Department of Imaging and Department of Gastroenterology, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Gastrointestinal Stromal Tumors (GISTs)

Gastrointestinal stromal tumors (GISTs) are common mesenchymal tumors typically found in the gastrointestinal tract, with the stomach being the most common site (60-70%)[3].

GISTs typically appear as well-defined, exophytic, and hypervascular masses that usually arise from the wall of the gastric body or antrum. Smaller tumors (<5 cm) are often intramural, whereas larger tumors (≥5 cm) may exhibit heterogeneous enhancement and commonly display central ulceration, necrosis, calcifications, and metastasis. [6, 7].

Features suggestive of malignancy include size >5 cm, irregular margins, and invasion of adjacent organs. However, definitive diagnosis requires histopathology [6].

Fig 3: A 79-year-old female with a gastrointestinal stromal tumor (GIST). Axial (a) and coronal (b) CT scans show a cystic lesion (arrow) with irregularly thickened and hyperenhancing walls in the posterior wall of the gastric antrum, measuring 46 mm. An EGD image (c) shows an ulcerated lesion and bulging of the posterior wall of the gastric antrum. References: Department of Imaging and Department of Gastroenterology, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Carcinoid Tumors

Gastric carcinoids are uncommon, accounting for only 0.3% of all gastric tumors. They are well-differentiated endocrine tumors with unique imaging characteristics and can be categorized into three subtypes, each with its own specific pathophysiological mechanism [3, 6].

On CT scans, Type 1 and 2 carcinoids appear as small, polypoid lesions in the gastric body and fundus. They are iso-dense in the pre-contrast phase but show marked enhancement during the arterial phase. Type 3 carcinoids, which are larger and more aggressive, may exhibit ulceration and are often associated with distant metastases [3].

Metastases

Metastatic involvement of the stomach is rare but can occur via hematogenous spread (melanoma, breast, lung and ovarian cancers), direct extension (pancreatic cancer), or lymphatic spread (esophageal cancer). CT findings include submucosal nodules, diffuse wall thickening, or a limits plastica appearance [6].

In patients with a known primary malignancy, the presence of submucosal lesions on CT, especially in cancers prone to gastric metastasis, should prompt consideration of gastric metastasis. Endoscopic biopsy is recommended for confirmation in such cases [5].

Benign Gastric Tumors

Gastric Lipoma

Lipomas are benign submucosal masses that are well-defined and homogeneous, with fat attenuation (-70 to -120 HU). They are usually asymptomatic but can lead to outlet obstruction or intussusception if they are large and located near the gastric pylorus [5].

Fig 4: Fig. : A 64-year-old female with a gastric lipoma. Axial (a) and coronal (b) CT scans show an incidental submucosal mass (arrow) with fat attenuation in the gastric antrum, measuring 52 mm. An EGD image (c) shows a submucosal lesion with endoluminal protrusion in the anterior wall of the gastric antrum. References: Department of Imaging and Department of Gastroenterology, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Gastric Leiomyoma

Leiomyomas are typically submucosal tumors that present as smooth, well-defined masses with homogeneous low enhancement and endoluminal growth pattern. They are usually less than 5 cm in size, although large tumors may ulcerate or perforate. [8].

Fig 5: A 50-year-old female with a gastric leiomyoma. Axial (a) and coronal (b) CT scans show a well-defined, homogeneous nodular formation with regular contours in the wall of the gastric cardia (arrow), measuring 34 mm. An EGD image (c) shows a bulge in the cardia region, initially interpreted as a hernia. References: Department of Imaging and Department of Gastroenterology, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Inflammatory Conditions

Gastritis

Gastritis is a common stomach condition characterized by inflammation in the stomach wall. CT scans may show either diffuse or focal thickening of the wall, typically with increased enhancement of the mucosa and a hypodense submucosal layer due to edema, often presenting a "halo" appearance [5].

Peptic Ulcers

Peptic ulcers, often caused by H. pylori or NSAIDs, may show mucosal disruption, luminal outpouching, wall thickening, or hyperenhancement on CT. Complications like perforation (extraluminal gas) or bleeding (contrast extravasation) are detectable. Focal, eccentric wall thickening >1 cm suggests malignancy, warranting endoscopy. CT aids in diagnosing and localizing bleeding sources [5, 8].

Fig 6: A 77-year-old male with a giant peptic ulcer. Axial (a) and coronal (b) CT scans show a discontinuity in the wall of the lesser gastric curvature (arrow), containing material identical to gastric contents, measuring approximately 5 cm. An EGD image (c) shows a giant, deep ulcer in the lesser curvature of the gastric antrum and incisura. References: Department of Imaging and Department of Gastroenterology, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Other Conditions

Gastric Pneumatosis

Gastric pneumatosis can be seen on CT as linear or cystic gas collections within the gastric wall. Gas in the rugae can mimic pneumatosis, so sagittal/coronal reconstructions can help with the diagnosis. Emphysematous gastritis, a life-threatening condition, is characterized by mottled air in the gastric wall with associated thickening [8].

Fig 7: A 73-year-old male with gastric pneumatosis following intestinal obstruction due to adhesions. Axial (a) and coronal (b) CT scans show significant gastric distension despite a nasogastric tube being correctly positioned, along with gastric pneumatosis (arrow) in the posterior wall of the gastric fundus. References: Department of Imaging, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Bezoars

Bezoars are intraluminal masses formed from ingested materials like hair (trichobezoars), vegetable matter (phytobezoars), milk (lactobezoars), or medications (pharmacobezoars). They appear on CT as mobile gastric filling defects with a mottled appearance due to trapped air. While often confined to the stomach, they can extend into the intestines (Rapunzel syndrome) [3].

Fig 8: An 82-year-old male, completely dependent, has a gastric bezoar. Axial (a) and coronal (b) CT scans show a heterogeneous mass with a mottled gas pattern (arrow) in the stomach, measuring 70 x 57 mm. References: Department of Imaging, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Gastric Volvulus

Acute gastric volvulus is a surgical emergency due to risks of ischemia, perforation, and necrosis. Types include organoaxial (most common), mesenteroaxial, and mixed. MDCT shows antrum displacement above the fundus and antropyloric transition point. Organoaxial involves stomach rotation along the long axis, while mesenteroaxial rotates along the short axis [9].

Fig 9: Fig.: An 80-year-old female with a mesenteroaxial gastric volvulus. Axial CT scans show marked gastric distension, with the pylorus (b) located superiorly and anteriorly to the esophagogastric junction (c). References: Department of Imaging, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Ectopic Pancreas

Ectopic pancreas presents as an ill-defined submucosal mass with endoluminal growth, usually in the distal antrum. It has enhancement similar to pancreatic tissue and may exhibit a central ductal structure on high-resolution CT. [3].

Gastric Varices

Gastric varices arise from flow reversal in the gastric fundal venous plexus, often due to portal hypertension from cirrhosis or splenic vein thrombosis. CT shows dilated, contrast-filled vessels along the lesser curvature, often contiguous with esophageal varices. Bleeding is less frequent but more severe than esophageal varices, with higher mortality. CT also visualizes afferent/efferent veins and collateral vessels [8].

Fig 10: A 60-year-old male with large gastroesophageal varices (GOV). Axial (a) and coronal (b) CT scans after contrast administration show large gastroesophageal varices (arrow) located near the lesser curvature and cardia. Additionally, signs of chronic liver disease, portal vein dilation, and splenomegaly are observed. References: Department of Imaging, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT

Gastric Diverticulum

Gastric diverticula are sac-like outpouchings that typically arise from the posterior surface of the gastric fundus near the spleen, adrenal gland, and left diaphragm. On CT scans, they appear as thin-walled cystic lesions with an air-fluid level [10].

Fig 11: A 67-year-old female with a gastric diverticulum. Axial (a) and coronal (b) CT scans show an incidental fluid-filled image (arrow) with an air-fluid level in the posterolateral wall of the gastric fundus, measuring 49 mm, consistent with a non-complicated diverticulum. Barium meal fluoroscopic image (c) shows contrast filling a sac-like structure adjacent to the gastric fundus, consistent with a gastric diverticulum. References: Department of Imaging, Hospital Beatriz Ângelo, Unidade Local de Saúde de Loures-Odivelas, Loures, PRT