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(Radiographics. 1999;19:1435-1446.)
© RSNA, 1999

SCIENTIFIC EXHIBIT

Unusual Gastric Tumors: Radiologic-Pathologic Correlation1

Seong Ho Park, MD , Joon Koo Han, MD , Tae Kyoung Kim, MD , Joon Woo Lee, MD , Seok-Hyoung Kim, MD , Yong Il Kim, MD , Byung Ihn Choi, MD , Kyung Mo Yeon, MD and Man Chung Han, MD

1 From the Department of Radiology and Institute of Radiation Medicine (S.H.P., J.K.H., T.K.K., J.W.L., B.I.C., K.M.Y., M.C.H.) and the Department of Pathology (S.H.K., Y.I.K.), Seoul National University College of Medicine, 28 Yongon-Dong, Chongno-Gu, Seoul 110-744, Korea. Recipient of a Certificate of Merit award for a scientific exhibit at the 1998 RSNA scientific assembly. Received February 1, 1999; revision requested March 11 and received April 14; accepted April 15. Address reprint requests to J.K.H.


   Abstract
Top
 Abstract
INTRODUCTION
 RADIOLOGIC FEATURES OF UNUSUAL...
 UNUSUAL RADIOLOGIC FINDINGS IN...
 CONCLUSIONS
 References
 
The overlap of radiologic findings in many gastric tumors makes differentiation difficult. However, some unusual gastric tumors have characteristic radiologic features that may suggest a specific diagnosis. At barium study, lipomas typically manifest as a smooth submucosal mass or an ulcerated lesion with a "bull's-eye" appearance that is indistinguishable from other mesenchymal tumors. At computed tomography (CT), lipomas usually manifest as well-circumscribed submucosal masses with fat attenuation. At radiology, glomus tumors appear as smooth submucosal masses with or without ulceration and may contain tiny flecks of calcification. These tumors frequently demonstrate strong enhancement on early-phase contrast material–enhanced images. At barium study, lymphangiomas may appear as smooth intramural masses that are indistinguishable from other mesenchymal tumors. At CT, they manifest as nonenhancing extramucosal masses with homogeneous low attenuation. Diffuse lesions in Brunner gland hamartoma manifest as multiple small nodules, producing a characteristic "cobblestone" appearance. Lymphomas may have typical imaging features (eg, more pronounced and homogeneous mural thickening) that can help differentiate them from adenocarcinoma. In addition, adenocarcinomas may demonstrate unusual findings such as transpyloric spread, unusually large polyps, or intratumoral calcifications. Familiarity with these radiologic features of gastric tumors can help ensure correct diagnosis and proper management.

Index Terms: Adenocarcinoma, 72.321, 72.815 • Carcinoid, 72.316 • Hamartoma, 72.314 • Lipoma, 72.315 • Lymphoma, 72.34 • Paraganglioma, 72.3193 • Stomach, mucosa • Stomach, neoplasms, 72.311, 72.314, 72.315, 72.316, 72.3193, 72.3194, 72.34


   INTRODUCTION
Top
 Abstract
 INTRODUCTION
RADIOLOGIC FEATURES OF UNUSUAL...
 UNUSUAL RADIOLOGIC FINDINGS IN...
 CONCLUSIONS
 References
 
Gastric tumors may be classified as benign or malignant on the basis of their biologic behavior; epithelial and mesenchymal tumors may be similarly classified on the basis of their origin. More than 95% of malignant tumors of the stomach are adenocarcinomas (1). The remaining malignant tumors include lymphoma, sarcoma (eg, malignant gastrointestinal stromal tumor), carcinoid tumor, metastasis, and so on. Between 85% and 90% of gastric tumors are benign (2). About half of these benign tumors are mucosal lesions (mostly hyperplastic or adenomatous polyps) and about half are mesenchymal tumors (2).

Mesenchymal tumors of the gastrointestinal tract are divided into two broad groups. The first group consists of tumors that are identical to those arising in the somatic soft tissue. These include smooth muscle tumors (eg, leiomyoma, leiomyosarcoma), neural tumors (eg, schwannoma, neurofibroma, plexosarcoma), lipocytic tumors (eg, lipoma, liposarcoma), tumors originating from vascular and perivascular tissues (eg, glomus tumor, hemangioma, lymphangioma), and other tumors (3). The benign neoplasms in this first group are composed of well-differentiated mesenchymal cells. The second group is far larger and more important and consists primarily of spindle cells or epithelioid cells, which are different from typical somatic soft-tissue tumors and are unique to the gastrointestinal tract. These lesions are called gastrointestinal stromal tumors and constitute the largest category of primary nonepithelial neoplasms of the stomach (3). Previously, many lesions in this group were erroneously referred to as leiomyoma or leiomyosarcoma (4).

Although these lesions demonstrate different histologic findings, the overlap of radiologic findings in many gastric tumors makes differentiation difficult. Clinical manifestations also overlap and can vary from severe abdominal pain and acute abdomen to vague signs such as weight loss and anemia. Therefore, some gastric tumors cause diagnostic confusion, which may result in unnecessary surgery or inappropriate follow-up. However, some unusual gastric tumors have characteristic radiologic features that may suggest a specific diagnosis.

In this article, we discuss and illustrate the computed tomographic (CT) and barium imaging features of unusual gastric tumors including lipoma, schwannoma, glomus tumor, lymphangioma, Brunner gland hamartoma, carcinoid tumor, and lymphoma. In addition, we present unusual findings in several cases of gastric adenocarcinoma. These include transpyloric spread, unusually large polypoid lesions, and calcifications. We also correlate radiologic findings with findings at pathologic analysis.

In the CT evaluation of gastric lesions, water is often used as a negative oral contrast agent. Water is particularly well-suited for use as a gastric contrast agent because it has a relatively low attenuation (0–10 HU), which optimizes visualization of the enhancing gastric wall at CT and results in good gastric distention (5,6). Adequate gastric distention can be achieved with about 500–1000 mL of water (5–7). In the cases presented in this article, some CT scans were obtained with water as a negative oral contrast agent.


   RADIOLOGIC FEATURES OF UNUSUAL GASTRIC TUMORS
Top
 Abstract
 INTRODUCTION
 RADIOLOGIC FEATURES OF UNUSUAL...
UNUSUAL RADIOLOGIC FINDINGS IN...
 CONCLUSIONS
 References
 
Lipoma
Lipomas are benign submucosal tumors composed of mature adipose tissue. They account for about 2%–3% of benign gastric tumors (8) and are usually detected incidentally. However, large lipomas may have ulcerations as a result of pressure necrosis of the overlying mucosa (Fig 1) and cause gastrointestinal bleeding. Large lipomas can also cause intussusception or bowel obstruction. Lipomas tend to occur as solitary lesions, most frequently in the gastric antrum (9). Barium study typically reveals a smooth submucosal mass (Fig 1a) or an ulcerated lesion with a "bull's-eye" appearance that is indistinguishable from other mesenchymal tumors (2). At CT, lipoma usually appears as a well-circumscribed submucosal mass with uniform fat attenuation (Fig 1b) (2). Therefore, a gastric lipoma can be definitively diagnosed with CT in most cases, and unnecessary endoscopy or surgery can be avoided. However, if the tumor has ulcerations, inflammation and scar may extend for a considerable distance into the tumor and mask the lipomatous characteristics at CT (9).



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  		Figure 1a.   Lipoma of the stomach in a 64-year-old woman. (a) Image from a double-contrast barium study shows a well-circumscribed submucosal mass in the gastric antrum (arrows) with limited ulceration (arrowhead). (b) CT scan obtained with water as an oral contrast agent reveals the well-circumscribed submucosal mass with uniform fat attenuation (arrow). The overlying mucosa is clearly seen (arrowhead). (c) Photograph of the resected specimen demonstrates the yellowish tumor composed of fatty tissue.

 


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  		Figure 1b.   Lipoma of the stomach in a 64-year-old woman. (a) Image from a double-contrast barium study shows a well-circumscribed submucosal mass in the gastric antrum (arrows) with limited ulceration (arrowhead). (b) CT scan obtained with water as an oral contrast agent reveals the well-circumscribed submucosal mass with uniform fat attenuation (arrow). The overlying mucosa is clearly seen (arrowhead). (c) Photograph of the resected specimen demonstrates the yellowish tumor composed of fatty tissue.

 


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  		Figure 1c.   Lipoma of the stomach in a 64-year-old woman. (a) Image from a double-contrast barium study shows a well-circumscribed submucosal mass in the gastric antrum (arrows) with limited ulceration (arrowhead). (b) CT scan obtained with water as an oral contrast agent reveals the well-circumscribed submucosal mass with uniform fat attenuation (arrow). The overlying mucosa is clearly seen (arrowhead). (c) Photograph of the resected specimen demonstrates the yellowish tumor composed of fatty tissue.

 
Schwannoma
Neurogenic tumors of the stomach are rare, accounting for about 4% of all benign gastric tumors (10). The majority of these tumors are schwannomas (2). They are included in the smaller group of gastrointestinal mesenchymal tumors, which contains relatively well-differentiated tumors that are identical to those arising from the somatic soft tissue (3). At radiology, gastric schwannomas usually appear as discrete submucosal masses that are indistinguishable from other mesenchymal tumors (Fig 2). As they outgrow their blood supply, these lesions may undergo central necrosis and ulceration. Tumors of the larger group (gastrointestinal stromal tumors) can also show some differentiation toward neural elements. Schwannomas and gastrointestinal stromal tumors that show differentiation toward neural elements are histologically different tumors, although the relation between them is not clear (4).



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  		Figure 2a.   Schwannoma of the stomach in a 74-year-old woman. (a) Image from a double-contrast barium study shows a large, well-circumscribed mass in the upper body of the stomach. Note fading out of the mucosal folds around the mass (arrow), a finding that is characteristic of a submucosal tumor. (b) Contrast-enhanced CT scan obtained with water as an oral contrast agent shows the well-circumscribed mass with homogeneous enhancement (arrow).

 


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  		Figure 2b.   Schwannoma of the stomach in a 74-year-old woman. (a) Image from a double-contrast barium study shows a large, well-circumscribed mass in the upper body of the stomach. Note fading out of the mucosal folds around the mass (arrow), a finding that is characteristic of a submucosal tumor. (b) Contrast-enhanced CT scan obtained with water as an oral contrast agent shows the well-circumscribed mass with homogeneous enhancement (arrow).

 
Glomus Tumor
Like neurogenic tumors, vascular tumors of the stomach are rare, accounting for about 2% of all benign gastric tumors. They include glomus tumor, lymphangioma, and other rare tumors (10). Glomus tumors are the most common benign vascular tumors of the stomach (10). Glomus tumors typically originate from glomus bodies, which are specialized arteriovenous communications that regulate skin temperature. Although glomus tumors in subungual locations had already been widely reported, it was not until 1951 that they were documented to occur in the stomach (9). Glomus tumors usually occur in the gastric antrum and are typically single tumors (9). The majority of affected patients are asymptomatic. However, the larger lesions are likely to be ulcerated and may cause upper gastrointestinal bleeding. At radiology, these tumors appear as smooth submucosal masses with or without ulceration (Fig 3) (2). Occasionally, glomus tumors may contain tiny flecks of calcification (Fig 3b) (11). These tumors enhance strongly on early-phase contrast material–enhanced images (Fig 3c), which reflects their hypervascular nature. At histologic analysis, glomus tumors appear as highly vascular tumors with dilated, irregularly shaped, thin-walled vessels that are probably modified capillaries and are covered by nests, strands, or sheets of glomus cells (Fig 3e) (9).



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  		Figure 3a.   Glomus tumor of the stomach in a 33-year-old woman. (a) Image from a double-contrast barium study shows a lobulated mass on the gastric angle (black arrows). Ulceration is seen centrally (white arrow). (b) Unenhanced CT scan shows the well-circumscribed mass with small flecks of calcification (arrows). (c) On an early-phase contrast-enhanced CT scan, the mass is greatly enhanced. (d) On an equilibrium-phase CT scan, the mass is less enhanced. (e) Photograph of the gastrectomy specimen shows the submucosal mass with central ulceration (arrow). (f) High-power photomicrograph (original magnification, x200; hematoxylin-eosin [H-E] stain) of the tumor specimen reveals small glomus cells intermixed with numerous small vessels (arrows).

 


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  		Figure 3b.   Glomus tumor of the stomach in a 33-year-old woman. (a) Image from a double-contrast barium study shows a lobulated mass on the gastric angle (black arrows). Ulceration is seen centrally (white arrow). (b) Unenhanced CT scan shows the well-circumscribed mass with small flecks of calcification (arrows). (c) On an early-phase contrast-enhanced CT scan, the mass is greatly enhanced. (d) On an equilibrium-phase CT scan, the mass is less enhanced. (e) Photograph of the gastrectomy specimen shows the submucosal mass with central ulceration (arrow). (f) High-power photomicrograph (original magnification, x200; hematoxylin-eosin [H-E] stain) of the tumor specimen reveals small glomus cells intermixed with numerous small vessels (arrows).

 


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  		Figure 3c.   Glomus tumor of the stomach in a 33-year-old woman. (a) Image from a double-contrast barium study shows a lobulated mass on the gastric angle (black arrows). Ulceration is seen centrally (white arrow). (b) Unenhanced CT scan shows the well-circumscribed mass with small flecks of calcification (arrows). (c) On an early-phase contrast-enhanced CT scan, the mass is greatly enhanced. (d) On an equilibrium-phase CT scan, the mass is less enhanced. (e) Photograph of the gastrectomy specimen shows the submucosal mass with central ulceration (arrow). (f) High-power photomicrograph (original magnification, x200; hematoxylin-eosin [H-E] stain) of the tumor specimen reveals small glomus cells intermixed with numerous small vessels (arrows).

 


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  		Figure 3d.   Glomus tumor of the stomach in a 33-year-old woman. (a) Image from a double-contrast barium study shows a lobulated mass on the gastric angle (black arrows). Ulceration is seen centrally (white arrow). (b) Unenhanced CT scan shows the well-circumscribed mass with small flecks of calcification (arrows). (c) On an early-phase contrast-enhanced CT scan, the mass is greatly enhanced. (d) On an equilibrium-phase CT scan, the mass is less enhanced. (e) Photograph of the gastrectomy specimen shows the submucosal mass with central ulceration (arrow). (f) High-power photomicrograph (original magnification, x200; hematoxylin-eosin [H-E] stain) of the tumor specimen reveals small glomus cells intermixed with numerous small vessels (arrows).

 


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  		Figure 3e.   Glomus tumor of the stomach in a 33-year-old woman. (a) Image from a double-contrast barium study shows a lobulated mass on the gastric angle (black arrows). Ulceration is seen centrally (white arrow). (b) Unenhanced CT scan shows the well-circumscribed mass with small flecks of calcification (arrows). (c) On an early-phase contrast-enhanced CT scan, the mass is greatly enhanced. (d) On an equilibrium-phase CT scan, the mass is less enhanced. (e) Photograph of the gastrectomy specimen shows the submucosal mass with central ulceration (arrow). (f) High-power photomicrograph (original magnification, x200; hematoxylin-eosin [H-E] stain) of the tumor specimen reveals small glomus cells intermixed with numerous small vessels (arrows).

 


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  		Figure 3f.   Glomus tumor of the stomach in a 33-year-old woman. (a) Image from a double-contrast barium study shows a lobulated mass on the gastric angle (black arrows). Ulceration is seen centrally (white arrow). (b) Unenhanced CT scan shows the well-circumscribed mass with small flecks of calcification (arrows). (c) On an early-phase contrast-enhanced CT scan, the mass is greatly enhanced. (d) On an equilibrium-phase CT scan, the mass is less enhanced. (e) Photograph of the gastrectomy specimen shows the submucosal mass with central ulceration (arrow). (f) High-power photomicrograph (original magnification, x200; hematoxylin-eosin [H-E] stain) of the tumor specimen reveals small glomus cells intermixed with numerous small vessels (arrows).

 
Lymphangioma
Lymphangiomas rarely affect the gastrointestinal tract. They are benign vascular tumors that are even rarer than glomus tumors (10). Lymphangiomas are usually found incidentally; however, they are occasionally large enough to cause obstructive symptoms or intussusception. Lymphangiomas are thought to arise from sequestered lymphatic tissue that fails to communicate with the normal lymphatic system (2). At barium study, lymphangiomas may appear as smooth intramural masses that are indistinguishable from other mesenchymal tumors (Fig 4a) (2). At CT, they may appear as nonenhancing extramucosal masses with homogeneous low attenuation (Fig 4b), making it difficult to differentiate them from cystic lesions of the stomach such as enteric duplication, resolving hematoma, abscess, necrotic tumor, and heterotopic pancreas (12). At histologic analysis, lymphangiomas consist of irregularly dilated lymphatic channels lined by benign-appearing endothelial cells.



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  		Figure 4a.   Lymphangioma of the stomach in a 57-year-old man. (a) Image from a double-contrast barium study shows a mass with a smooth surface and a broad base on the gastric angle (arrows). (b) Contrast-enhanced CT scan obtained with water as an oral contrast agent shows the lentiform submucosal mass with homogeneous low attenuation (arrow).

 


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  		Figure 4b.   Lymphangioma of the stomach in a 57-year-old man. (a) Image from a double-contrast barium study shows a mass with a smooth surface and a broad base on the gastric angle (arrows). (b) Contrast-enhanced CT scan obtained with water as an oral contrast agent shows the lentiform submucosal mass with homogeneous low attenuation (arrow).

 
Brunner Gland Hamartoma
Brunner gland hamartoma is probably not a true neoplasm but rather glandular hyperplasia or a hamartoma. The lesion occurs mainly in the duodenum and only rarely in the stomach, where it is always seen in the prepyloric region (13). These lesions account for 1.2% of all gastric polyps (14). To our knowledge, there has been no report of malignant degeneration (2). Nevertheless, Brunner gland hamartomas can be mistaken for neoplastic lesions at radiology or endoscopy and can occasionally cause signs such as upper gastrointestinal bleeding or obstruction (2). They can also act as the lead point for intussusception (Fig 5). Most of the lesions are less than 2 cm in diameter, but some are as large as 5 cm (13). The lesions may be diffuse or solitary. At radiology, diffuse lesions manifest as multiple small nodules, producing a characteristic "cobblestone" appearance. Differential diagnosis includes various polyposis syndromes, lymphoid hyperplasia, and (in cases of duodenal lesions) heterotopic gastric mucosa and nodular duodenitis (2). A solitary lesion manifests as a polyp. Adenomatous polyps and various submucosal tumors may be included in the differential diagnosis (2). At histologic analysis, Brunner gland hamartoma is characterized by nodular proliferation of normal Brunner gland tissue accompanied by ducts and scattered stromal elements (15).



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  		Figure 5a.   Brunner gland hamartoma in the pylorus causing gastroduodenal intussusception in a 48-year-old woman. (a) Image from a double-contrast barium study shows distally tapered barium streaks in the duodenum representing intussusceptum (white arrows) and the "coiled spring" appearance of the duodenum (open arrows). A lobulated filling defect in the duodenojejunal junction (solid black arrow) suggests a lead point. (b) Photograph of the gastrectomy specimen shows the polypoid lesion with ulceration (white arrow) and a long (5-cm) stalk (black arrow) at the pylorus of the stomach. D = duodenum, P = pylorus, S = stomach. Scale is in centimeters.

 


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  		Figure 5b.   Brunner gland hamartoma in the pylorus causing gastroduodenal intussusception in a 48-year-old woman. (a) Image from a double-contrast barium study shows distally tapered barium streaks in the duodenum representing intussusceptum (white arrows) and the "coiled spring" appearance of the duodenum (open arrows). A lobulated filling defect in the duodenojejunal junction (solid black arrow) suggests a lead point. (b) Photograph of the gastrectomy specimen shows the polypoid lesion with ulceration (white arrow) and a long (5-cm) stalk (black arrow) at the pylorus of the stomach. D = duodenum, P = pylorus, S = stomach. Scale is in centimeters.

 
Carcinoid Tumor
Carcinoid tumors of the stomach originate from Kulchitsky cells in the crypts of Lieberkühn. Because the cytoplasm contains eosinophilic granules that have an affinity for silver stain, these lesions have also been called argentaffinomas (16). Less than 3% of gastrointestinal carcinoid tumors are located in the stomach (10,16). Most gastric carcinoid tumors are located in the distal antrum, often on the lesser curvature (16). Many patients are asymptomatic; however, others may present with abdominal pain, nausea, vomiting, weight loss, anorexia, or gastrointestinal bleeding. Unlike carcinoid tumors in the ileocecal area, gastric carcinoid tumors rarely produce carcinoid syndrome. They are low-grade malignancies that can eventually metastasize. Gastric carcinoid tumors demonstrate a variety of radiologic findings. The majority of tumors manifest as one or more submucosal-appearing masses ranging from 1 to 4 cm in size. When ulceration is present, the lesion may have a bull's-eye appearance (16,17). Gastric carcinoid tumors may also manifest as one or more sessile or pedunculated polyps that are indistinguishable from hyperplastic or adenomatous polyps (Fig 6) (16). Other lesions may manifest with benign-appearing or malignant-appearing gastric ulcers (16,17).



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  		Figure 6a.   Carcinoid tumor of the stomach in a 66-year-old man. (a) Image from a double-contrast barium study shows a polypoid lesion in the gastric fundus (white arrow) with a lobulated surface and ulceration (black arrow). (b) Photograph of the gastrectomy specimen demonstrates the 2.5-cm polypoid mass with central ulceration in the gastric fundus (arrow).

 


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  		Figure 6b.   Carcinoid tumor of the stomach in a 66-year-old man. (a) Image from a double-contrast barium study shows a polypoid lesion in the gastric fundus (white arrow) with a lobulated surface and ulceration (black arrow). (b) Photograph of the gastrectomy specimen demonstrates the 2.5-cm polypoid mass with central ulceration in the gastric fundus (arrow).

 
Lymphoma
Gastric lymphomas account for about 50% of all gastrointestinal lymphomas and 3%–5% of all malignant neoplasms in the stomach (16). Lymphomas may be infiltrative with thickened folds, polypoid, ulcerated, nodular, or a combination thereof (Figs 7, 8) (16,18). Although some radiologic features may help differentiate lymphomas from gastric adenocarcinomas, it is not always possible to differentiate the two lesions. Gastric wall thickening is more pronounced and more homogeneous in lymphoma than in adenocarcinoma, and the perigastric fat plane is more likely to be preserved (19). When adenocarcinomas manifest as diffusely thickened folds, the gastric wall is rigid and there is luminal narrowing. In lymphoma, the gastric wall is pliant and luminal narrowing is rare despite diffuse fold thickening (16). Adenopathy in lymphoma may extend below the level of the renal veins without perigastric adenopathy, a finding that is not seen in gastric cancer. In addition, the lymph nodes are usually larger in lymphoma than in adenocarcinoma (19).



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  		Figure 7a.   Low-grade mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach in a 48-year-old man. (a) Image from a double-contrast barium study shows diffuse nodularity of the gastric wall from the high body to the antrum. (b) Photograph of the gastrectomy specimen clearly depicts diffuse nodularity of the gastric mucosa. (c) Low-power photomicrograph (original magnification, x10; H-E stain) reveals lymphoma cells (blue stain) diffusely infiltrating the mucosa and submucosa.

 


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  		Figure 7b.   Low-grade mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach in a 48-year-old man. (a) Image from a double-contrast barium study shows diffuse nodularity of the gastric wall from the high body to the antrum. (b) Photograph of the gastrectomy specimen clearly depicts diffuse nodularity of the gastric mucosa. (c) Low-power photomicrograph (original magnification, x10; H-E stain) reveals lymphoma cells (blue stain) diffusely infiltrating the mucosa and submucosa.

 


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  		Figure 7c.   Low-grade mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach in a 48-year-old man. (a) Image from a double-contrast barium study shows diffuse nodularity of the gastric wall from the high body to the antrum. (b) Photograph of the gastrectomy specimen clearly depicts diffuse nodularity of the gastric mucosa. (c) Low-power photomicrograph (original magnification, x10; H-E stain) reveals lymphoma cells (blue stain) diffusely infiltrating the mucosa and submucosa.

 


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  		Figure 8a.   High-grade MALT lymphoma of the stomach in a 53-year-old woman. (a, b) Images from a double-contrast barium study that were obtained with the patient in different positions show multiple masses of variable size in the body and antrum of the stomach (solid arrows). Some of the masses have ulceration (arrowheads in b). Some nodular lesions (open arrow in b) are also seen in the duodenal bulb and proved to be transpyloric extension of gastric lymphoma at endoscopic biopsy. (c) CT scan shows wall thickening of the gastric antrum (white arrows) and several masses on the gastric wall (black arrows). (d) Photograph of the gastrectomy specimen reveals multiple masses in the body and antrum of the stomach (arrows), some of which have ulceration (arrowheads).

 


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  		Figure 8b.   High-grade MALT lymphoma of the stomach in a 53-year-old woman. (a, b) Images from a double-contrast barium study that were obtained with the patient in different positions show multiple masses of variable size in the body and antrum of the stomach (solid arrows). Some of the masses have ulceration (arrowheads in b). Some nodular lesions (open arrow in b) are also seen in the duodenal bulb and proved to be transpyloric extension of gastric lymphoma at endoscopic biopsy. (c) CT scan shows wall thickening of the gastric antrum (white arrows) and several masses on the gastric wall (black arrows). (d) Photograph of the gastrectomy specimen reveals multiple masses in the body and antrum of the stomach (arrows), some of which have ulceration (arrowheads).

 


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  		Figure 8c.   High-grade MALT lymphoma of the stomach in a 53-year-old woman. (a, b) Images from a double-contrast barium study that were obtained with the patient in different positions show multiple masses of variable size in the body and antrum of the stomach (solid arrows). Some of the masses have ulceration (arrowheads in b). Some nodular lesions (open arrow in b) are also seen in the duodenal bulb and proved to be transpyloric extension of gastric lymphoma at endoscopic biopsy. (c) CT scan shows wall thickening of the gastric antrum (white arrows) and several masses on the gastric wall (black arrows). (d) Photograph of the gastrectomy specimen reveals multiple masses in the body and antrum of the stomach (arrows), some of which have ulceration (arrowheads).

 


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  		Figure 8d.   High-grade MALT lymphoma of the stomach in a 53-year-old woman. (a, b) Images from a double-contrast barium study that were obtained with the patient in different positions show multiple masses of variable size in the body and antrum of the stomach (solid arrows). Some of the masses have ulceration (arrowheads in b). Some nodular lesions (open arrow in b) are also seen in the duodenal bulb and proved to be transpyloric extension of gastric lymphoma at endoscopic biopsy. (c) CT scan shows wall thickening of the gastric antrum (white arrows) and several masses on the gastric wall (black arrows). (d) Photograph of the gastrectomy specimen reveals multiple masses in the body and antrum of the stomach (arrows), some of which have ulceration (arrowheads).

 
Recently, low-grade MALT lymphoma has been reported to account for as many as 50%–72% of all primary gastric lymphomas (20). Most lesions that were previously considered to be gastric pseudolymphomas are low-grade MALT lymphomas by current criteria (21). Low-grade MALT lymphomas are unique in that they are associated with Helicobacter pylori infection and may regress completely after antibiotic therapy for H pylori. At radiology, low-grade MALT lymphomas frequently demonstrate nonspecific findings such as mucosal nodularity, depressed lesions, and thickened folds. When they manifest as mucosal nodularity, gastritis (including H pylori gastritis), leukemic infiltration, or even a polyposis syndrome may be included in the differential diagnosis (Fig 7) (20, 22). When they manifest as depressed lesions, differentiation from gastric adenocarcinoma is quite difficult.


   UNUSUAL RADIOLOGIC FINDINGS IN GASTRIC ADENOCARCINOMA
Top
 Abstract
 INTRODUCTION
 RADIOLOGIC FEATURES OF UNUSUAL...
 UNUSUAL RADIOLOGIC FINDINGS IN...
CONCLUSIONS
 References
 
Transpyloric Spread of Gastric Adenocarcinoma
Transpyloric spread of gastric malignant tumors usually occurs by means of direct infiltration through the submucosa or subserosa and less frequently by means of lymphatic transport through the submucosal layer (23). In the past, extension of a gastric tumor to the duodenum was generally assumed to be a distinguishing sign of lymphomas of the stomach. However, duodenal invasion by gastric adenocarcinomas (Fig 9) is not as rare as was thought previously. Radiographically detectable transpyloric spread of gastric adenocarcinoma has been reported to occur in 5%–25% of cases (23). Transpyloric extension of gastric lymphoma is more common than that of gastric adenocarcinoma and has been reported in up to 40% of cases (23). However, adenocarcinoma is by far the most common malignant gastric tumor; therefore, a gastric tumor involving the duodenum is more likely to be an adenocarcinoma despite the slightly higher prevalence of transpyloric extension in gastric lymphoma.



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  		Figure 9.   Transpyloric spread of a gastric adenocarcinoma in a 40-year-old man. Image from a double-contrast barium study shows diffuse thickening and irregularity of the mucosal folds in the antrum of the stomach (white arrows). Lobulated masses are seen in the duodenal bulb (black arrow). These lesions proved to be transpyloric spread of gastric adenocarcinoma at endoscopic biopsy.

 
Unusually Large Polypoid Early Gastric Cancer
Early gastric cancer is defined as a gastric carcinoma that is limited to the mucosa and submucosa regardless of whether lymph node involvement is present (24,25). The Japanese Research Society for Gastric Cancer has divided early gastric cancers into three types. Type I early gastric cancers manifest as elevated lesions that protrude more than 5 mm into the lumen (24,25). However, some of these lesions may be quite large, measuring up to 10 cm (Fig 10) (26). Therefore, polypoid carcinomas of the stomach cannot be definitely diagnosed as early or advanced lesions on the basis of size alone. Various polypoid lesions can develop in the stomach, but the differential diagnosis of relatively large polypoid lesions (>1 cm) may include polypoid carcinoma, adenomatous polyp, or atypical hyperplastic polyp. Because adenomatous polyp may undergo malignant degeneration, carcinoma should be suspected in any gastric polyps greater than 1 cm in size.



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  		Figure 10a.   Early gastric carcinoma in a 59-year-old man. (a, b) Image from a double-contrast barium study (a) and CT scan obtained with water as an oral contrast agent (b) show a large polypoid lesion with a lobulated surface in the anterior wall of the proximal antrum (arrow). (c) Photograph of the gastrectomy specimen shows a polypoid lesion measuring 3.7 x 2.2 cm in the anterior wall of the gastric antrum (arrow). Surface lobulation is also noted. Histologic analysis revealed that the lesion was an adenocarcinoma confined to the mucosa and submucosa.

 


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  		Figure 10b.   Early gastric carcinoma in a 59-year-old man. (a, b) Image from a double-contrast barium study (a) and CT scan obtained with water as an oral contrast agent (b) show a large polypoid lesion with a lobulated surface in the anterior wall of the proximal antrum (arrow). (c) Photograph of the gastrectomy specimen shows a polypoid lesion measuring 3.7 x 2.2 cm in the anterior wall of the gastric antrum (arrow). Surface lobulation is also noted. Histologic analysis revealed that the lesion was an adenocarcinoma confined to the mucosa and submucosa.

 


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  		Figure 10c.   Early gastric carcinoma in a 59-year-old man. (a, b) Image from a double-contrast barium study (a) and CT scan obtained with water as an oral contrast agent (b) show a large polypoid lesion with a lobulated surface in the anterior wall of the proximal antrum (arrow). (c) Photograph of the gastrectomy specimen shows a polypoid lesion measuring 3.7 x 2.2 cm in the anterior wall of the gastric antrum (arrow). Surface lobulation is also noted. Histologic analysis revealed that the lesion was an adenocarcinoma confined to the mucosa and submucosa.

 
Calcified Gastric Carcinoma
Radiologically visible calcifications in primary gastric cancer are rare and are usually seen in mucinous adenocarcinoma (27,28). Mucinous adenocarcinoma is characterized by prominent glandular formations and abundant mucin deposition, nearly all of which is extracellular (4). Calcifications are present in the mucin pool, and the mechanism of calcification is thought to be related to alkaline mucin, which predisposes calcium salts to precipitate (28). Miliary and punctate calcifications are thought to be diagnostic for mucinous adenocarcinoma (Fig 11) (27). At CT, mucinous adenocarcinoma may also manifest as a thickened gastric wall with diffuse low attenuation due to the large amount of mucin (Fig 11b) (29). Other gastrointestinal tumors that may contain calcifications include gastrointestinal stromal tumors and hemangiomas. Calcifications in gastrointestinal stromal tumor are typically amorphous, and in hemangioma they typically manifest as clusters of phleboliths in the gastrointestinal wall (30).



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  		Figure 11a.   Calcified mucinous adenocarcinoma of the stomach in a 62-year-old woman. (a) Image from a double-contrast barium study shows an encircling mass causing luminal narrowing in the gastric antrum (arrows). (b) CT scan obtained with water as an oral contrast agent shows wall thickening of the gastric antrum with diffuse low attenuation (curved arrow). Punctate calcifications (straight arrow) are noted within the thickened gastric wall.

 


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  		Figure 11b.   Calcified mucinous adenocarcinoma of the stomach in a 62-year-old woman. (a) Image from a double-contrast barium study shows an encircling mass causing luminal narrowing in the gastric antrum (arrows). (b) CT scan obtained with water as an oral contrast agent shows wall thickening of the gastric antrum with diffuse low attenuation (curved arrow). Punctate calcifications (straight arrow) are noted within the thickened gastric wall.

 

   CONCLUSIONS
Top
 Abstract
 INTRODUCTION
 RADIOLOGIC FEATURES OF UNUSUAL...
 UNUSUAL RADIOLOGIC FINDINGS IN...
 CONCLUSIONS
References
 
Radiologic findings in many gastric tumors are varied and overlap with one another. However, some gastric tumors such as lipoma, glomus tumor, and lymphangioma have typical features that may suggest a specific diagnosis. Gastric adenocarcinomas may demonstrate unusual findings such as transpyloric spread, unusually large polyps, or intratumoral calcifications. Familiarity with the radiologic features of unusual gastric tumors and with unusual radiologic findings in gastric adenocarcinoma can help ensure correct diagnosis and proper management.


   Footnotes
 
Abbreviation: MALT = mucosa-associated lymphoid tissue


   References
Top
 Abstract
 INTRODUCTION
 RADIOLOGIC FEATURES OF UNUSUAL...
 UNUSUAL RADIOLOGIC FINDINGS IN...
 CONCLUSIONS
 References
 

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