A number of features in this case favored a diagnosis of primary gastric lymphoma, rather than secondary/systemic lymphoma or an alternative diagnosis of adenocarcinoma:

• linitis plastica appearance
• extension along the duodenum
• absence of gastric outlet obstruction symptoms
• no splenomegaly, adjacent lymphadenopathy, and normal retroperitoneum 

There was also evidence of omental caking and peritoneal carcinomatosis.

Upper GI endoscopy was performed and the histopathology results yielded Burkitt lymphoma (B-cell non-Hodgkin lymphoma).

Histopathology report:

Biopsies of gastric mucosal fragments show surface ulceration and infiltration by malignant tumor cells predominantly in an interstitial pattern, composed of uniform medium-sized lymphocytes with round neuclei, finely dispersed chromatin and multiple small nucleoli.  Numerous mitotic figures and apoptotic bodies are noted.  Negative for H.pylori and intestinal metaplasia.  Cautery artifact is noted.

Immunohistochemistry:

• The tumor cells are diffusely positive for LCA, CD20, CD79a, BCI-6 and CD10.
• Tumor cells are negative for CD3, CD5, CD23, Cyclin D1, Bcl-2, and Tdt.
• Ki-67 proliferation index is near 100%.

Diagnosis: positive involvement by high-grade Non Hodgkin's B-cell lymphoma - Burkitt type.

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Special thanks to Dr Mohammed A. Al Sayegh.