Gastric Metastases and Lymphoma

Published on 19/07/2015 by admin

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 Bull’s-eye lesions on imaging

• Best imaging tool

image CECT with MPRs; barium (single or double) contrast studies

TOP DIFFERENTIAL DIAGNOSES

• Gastric carcinoma
• Gastric stromal tumor (GIST)
• Gastritis (erosive type)
• Pancreatitis (extrinsic inflammation)

PATHOLOGY

• Gastric lymphoma is classified into 2 types based on pathology

image Low-grade MALT lymphoma
image High-grade or advanced non-Hodgkin lymphoma

CLINICAL ISSUES

• Complications

image Upper GI bleeding and perforation in ulcerated lesions
image Antral lesion + pyloric extension: Outlet obstruction
• Treatment

image Radiation and/or chemotherapy; surgical resection of lesions for bleeding or perforation
image Eradication of Helicobacter pylori for gastric lymphoma
• Prognosis: Poor for gastric metastases; good for MALT lymphoma

DIAGNOSTIC CHECKLIST

• Check for history or evidence of of primary cancer or  H. pylori gastritis
• Image interpretation pearls

image Imaging important to suggest and stage malignancy, but biopsy is required
image
(Left) Axial CECT in a 69-year-old man shows widespread metastases from the patient’s known metastatic melanoma, including the gastric wall image, lymph nodes image, and omentum image.

image
(Right) Axial CECT in the same patient again illustrates classic widespread metastases from melanoma, here involving the small bowel image, lymph nodes image, and omentum image, with both nodular and diffuse metastases seen. In addition, the left ureter was obstructed due to a ureteral/retroperitoneal metastasis.
image
(Left) Upper GI in a 70-year-old man with weight loss and dyspepsia reveals distortion and blunting of the gastric folds. In spite of what appears to be diffuse involvement of the stomach, there is no outlet obstruction, and the stomach is distensible.

image
(Right) Axial CECT in the same patient shows massive thickening of the gastric wall of soft tissue attenuation. Note the extensive regional lymphadenopathy and omental tumor deposits image. These findings are typical of primary gastric lymphoma.

TERMINOLOGY

Definitions

• Metastases from primary extragastric cancer
• Lymphoma: Malignant gastric tumor of B lymphocytes

IMAGING

General Features

• Best diagnostic clue

image Bull’s-eye lesions on CT or upper GI series

Fluoroscopic Findings

• Fluoroscopic-guided barium study

image Malignant melanoma metastases

– Solitary or multiple discrete submucosal masses
– Bull’s-eye or “target” lesions: Centrally ulcerated submucosal masses
– “Spoke-wheel” pattern: Radiating superficial fissures from central ulcer
– Giant cavitated lesion: Large collection of barium (5-15 cm) communicating with lumen
image Breast carcinoma metastases

– Lobular breast cancer: Linitis plastica or “leather bottle” appearance (loss of distensibility of antrum and body + thickened irregular folds)
– Mucosal nodularity, spiculation, ulceration
image Esophageal carcinoma

– Large polypoid/ulcerated mass in gastric fundus
– Subtle findings of cardia: Small ulcers and nodules
image Pancreatic carcinoma

– Often indents, rarely invades stomach
– Pancreatic head: Extrinsic compression of medial border of gastric antrum
– Pancreas body or tail: Extrinsic compression of posterior wall of fundus or body
– Direct invasion: Spiculated mucosal folds, nodular mass effect, ulceration, obstruction
image Peritoneal and omental metastases may involve stomach

– Ovarian cancer and other primaries that cause peritoneal metastases
– Transverse colon cancer may invade stomach via gastrocolic ligament
– Most common sign is intramural mass along greater curvature
image Low-grade MALT lymphoma

– Rounded, confluent nodules of low-grade lymphoma

image Mimic enlarged areae gastricae of Helicobacter pylori gastritis
– Shallow, irregular ulcers with nodular surrounding mucosa
image High-grade/advanced lymphoma

– Infiltrative lesions: Massively enlarged folds with distorted and nodular contour

image Stomach remains pliable and distensible
– Ulcerative lesions with surrounding nodular mucosa and thickened, irregular folds; may appear as giant cavitated lesions
– Polypoid lymphoma: Lobulated intraluminal mass
– Nodular lesions: Submucosal nodules or masses often ulcerate, resulting in bull’s-eye or “target” lesions

CT Findings

• Demonstration of lesions facilitated by distention of stomach by water and gas
• Multiplanar reformation (MPRs) very useful to judge full extent of disease and relation to adjacent organs, nodes
• Hematogenous spread of metastases to stomach

image Malignant melanoma

– Bull’s-eye or “target” lesions, nodular intramural cavitated lesions
image Breast cancer: Linitis plastica or “leather bottle”

– Markedly thickened gastric wall with enhancement, folds preserved
– Mimics primary scirrhous carcinoma of stomach
• Direct invasion or lymphatic spread to stomach

image Distal esophageal carcinoma

– Polypoid, lobulated mass in gastric fundus
– Indistinguishable from primary gastric carcinoma
image Pancreatic carcinoma

– Irregular extrinsic gastric compression
– Pancreatic tumor will be evident
image Transverse colon cancer → gastrocolic ligament → greater curvature

– Thickened wall or mass in greater curvature ± gastrocolic fistulous tract
image Omental and peritoneal metastases: Ovary, uterus, pancreas, breast

– Can be seen as small as 1 cm
– Lacy reticular pattern to bulky masses (omental cake) displace and indent gastric wall
• Gastric lymphoma

image Markedly thickened gastric wall, regional or widespread adenopathy
image Mural density of stomach is soft tissue (not water density as in gastritis)
image Rarely causes linitis plastica or gastric outlet obstruction
image Transpyloric spread into duodenum may be seen

Ultrasonographic Findings

• Grayscale ultrasound

image Endoscopic ultrasonography (EUS)

– Hypoechoic mass disrupting normal wall layers

Imaging Recommendations

• Best imaging tool

image Helical CT; barium (single or double) contrast studies
image EUS for depth of invasion and guided biopsy

DIFFERENTIAL DIAGNOSIS

Gastric Carcinoma

• Polypoid, ulcerated, infiltrative types indistinguishable from gastric metastases and lymphoma
• Linitis plastica: Primary scirrhous type mimics metastatic breast cancer
• Loss of distensibility in scirrhous type differentiates from non-Hodgkin lymphoma (NHL)
• Hodgkin lymphoma indistinguishable from scirrhous due to similar desmoplastic response

Gastric Stromal Tumor (GIST)

• Usually occur as solitary lesions, mostly exophytic
• Also produce giant, cavitated lesions

Gastritis (Erosive Type)

• Multiple punctate barium collections surrounded by thin radiolucent halos of edematous mucosa
• Submucosal layer of gastric wall is near water density

Pancreatitis (Extrinsic Inflammation)

• Changes in greater curvature or posterior wall of stomach mimic omental metastatic invasion
• Peripancreatic inflammation evident on CT

Gastric Pseudolymphoma

• Rare extensive benign reactive hyperplasia within gastric wall
• Difficult or impossible to diagnose by imaging alone

PATHOLOGY

General Features

• Etiology

image Gastric metastases

– Malignant melanoma; carcinoma of breast, lung, pancreas, colon, esophagus
image Gastric lymphoma

– Arise from mucosa-associated lymphoid tissue (MALT) in patients with chronic H. pylori gastritis containing cytotoxin-associated antigen (CagA)

image May be cured with eradication of H. pylori
– Primary: NHL more common than secondary involvement
– Secondary lymphoma (generalized lymphoma)

image These are treated with radiation &/or systemic chemotherapy like other high grade lymphomas
• Associated abnormalities

image Extragastric primary carcinoma in gastric metastases
image Generalized adenopathy in secondary lymphoma

Staging, Grading, & Classification

• Classified into 2 types based on pathology

image Low-grade MALT lymphoma (most common type)

– Marginal zone B-cell NHL
image High-grade or advanced lymphoma

– Diffuse large B-cell NHL
• Ann Arbor staging of primary lymphoma

image Stage I: Involve gastric wall
image Stage II: Involve regional lymph nodes in abdomen
image Stage III: Nodes above and below diaphragm
image Stage IV: Widely disseminated lymphoma

Gross Pathologic & Surgical Features

• Solitary/multiple; polypoid, ulcerated, cavitated masses or “leather bottle” appearance of stomach

Microscopic Features

• Metastases: Varies based on primary cancer
• Lymphoma: Lymphoepithelial lesions

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Pain, weight loss, palpable mass; can be asymptomatic
image Hematemesis, melena, acute abdomen (perforation)

Demographics

• Age

image Usually middle-aged and elderly
• Gender

image Metastases (M = F), lymphoma (M > F)
• Epidemiology

image Gastric lymphoma

– Stomach is most frequently involved part of GI tract

image Constitutes 50% of all GI tract lymphomas, 25% of extranodal lymphomas
– > 50% of cases are primary gastric lymphoma
– 3-5% of all gastric malignancies
image Gastric metastases: Seen in < 2% who die of cancer
image Most patients with gastric metastases have known primary

– Occasionally may occur as initial manifestation of occult primary tumor
– Breast and kidney carcinoma can metastasize to stomach many years after primary treatment

Natural History & Prognosis

• Metastases to stomach

image Prognosis depends on effective treatment of primary tumor and its metastases
image Prognosis is generally poor
• MALT lymphoma has much better prognosis than primary gastric or secondary lymphoma

image May be cured in about 70% by eradication of H. pylori alone
• Complications

image Upper GI bleeding and perforation in ulcerated lesions
image Antral lesion + pyloric extension: Outlet obstruction

Treatment

• Eradication of H. pylori
• Radiation &/or chemotherapy, surgical resection of lesions if upper GI bleed or perforation

DIAGNOSTIC CHECKLIST

Consider

• Check for history or evidence of primary cancer or H. pylori gastritis

Image Interpretation Pearls

• Overlapping radiographic features of gastric metastases, lymphoma, and primary carcinoma
• Imaging important to suggest and stage malignancy, but biopsy is required for diagnosis

image
(Left) Axial CECT in a 57-year-old man with a known history of malignant melanoma, now presenting with weight loss and dyspepsia, shows metastases to the liver and gallbladder image. The stomach is not well distended or easily assessed.
image
(Right) Upper GI in the same patient illustrates classic bull’s-eye lesions image, consisting of small, intramural masses with a central ulceration.
image
(Left) Axial CECT in a 75-year-old man who presented with weight loss and dyspepsia demonstrates a soft tissue density mass image that diffusely infiltrates the gastric wall. There is no outlet obstruction.

image
(Right) Upper GI in the same patient reveals marked thickening and blunting of the gastric folds but nearly normal distensibility and no obstruction, findings typical of lymphoma.
image
(Left) Axial CECT in an 84-year-old woman with a known history of breast cancer and a recent onset of early satiety and nausea reveals gastric distension and retention of food. The antrum is nondistensible and is infiltrated with a soft tissue density mass image.

image
(Right) Upper GI in the same patient confirms a scirrhous lesion of the gastric antrum image causing delayed gastric emptying. These imaging findings are indistinguishable from primary gastric carcinoma.
image
Axial CECT shows gastric lymphoma. The entire stomach is involved with massive mural thickening.

image
Axial NECT shows massive circumferential thickening of gastric antral wall image but no obstruction in this patient with lymphoma.
image
Upper GI shows gastric lymphoma. The stomach is encased by the tumor with 2 large ulcerations image but no obstruction.
image
Upper GI shows circumferential massive thickening of gastric folds but no outlet obstruction in this patient with lymphoma.
image
Upper GI shows a submucosal polypoid mass image from metastatic melanoma.
image
Upper GI shows “bull’s-eye” lesion image, a discrete intramural polyp with central ulceration in this patient with metastatic melanoma.
image
Axial CECT shows diffuse thickening of the gastric wall and porto-caval adenopathy image in this patient with gastric lymphoma.
image
Axial CECT shows diffuse homogeneous thickening of the gastric wall and extensive perigastric lymphadenopathy image in this patient with gastric lymphoma.

SELECTED REFERENCES

1. Fischbach, W. MALT lymphoma: forget surgery? Dig Dis. 2013; 31(1):38–42.

2. Burke, JS. Lymphoproliferative disorders of the gastrointestinal tract: a review and pragmatic guide to diagnosis. Arch Pathol Lab Med. 2011; 135(10):1283–1297.

3. Kobayashi, A, et al. MR imaging of reactive lymphoid hyperplasia of the liver. J Gastrointest Surg. 2011; 15(7):1282–1285.

4. Hargunani, R, et al. Cross-sectional imaging of gastric neoplasia. Clin Radiol. 2009; 64(4):420–429.

5. Gollub, MJ. Imaging of gastrointestinal lymphoma. Radiol Clin North Am. 2008; 46(2):287–312. [ix].

6. Santacroce, L, et al. Helicobacter pylori infection and gastric MALTomas: an up-to-date and therapy highlight. Clin Ter. 2008; 159(6):457–462.

7. Ba-Ssalamah, A, et al. Dedicated multidetector CT of the stomach: spectrum of diseases. Radiographics. 2003; 23(3):625–644.

8. Horton, KM, et al. Current role of CT in imaging of the stomach. Radiographics. 2003; 23(1):75–87.

9. Park, MS, et al. Radiographic findings of primary B-cell lymphoma of the stomach: low-grade versus high-grade malignancy in relation to the mucosa-associated lymphoid tissue concept. AJR Am J Roentgenol. 2002; 179(5):1297–1304.

10. Fishman, EK, et al. CT of the stomach: spectrum of disease. Radiographics. 1996; 16(5):1035–1054.

11. McDermott, VG, et al. Malignant melanoma metastatic to the gastrointestinal tract. AJR Am J Roentgenol. 1996; 166(4):809–813.

12. Feczko, PJ, et al. Metastatic disease involving the gastrointestinal tract. Radiol Clin North Am. 1993; 31(6):1359–1373.