June 2015 Case of the Month

62 year-old male with longstanding history of acid reflux presented to the ER with abdominal discomfort and melena.  CT of the abdomen showed a possible mass in the stomach body.  Upper endoscopy revealed a single large ulcer in the body.  Multiple biopsies were taken of the ulcerated area.  What is your diagnosis?

4x
4x

Expansion of gastric lamina propria by lymphoid infiltrate.

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10x
10x

Distortion of gastric pits by lymphoid infiltrate.

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Lambda
Lambda

Mostly negative, indicating a skewed kappa:lambda ratio or clonal plasma cell component.

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4x
4x

Expansion of gastric lamina propria by lymphoid infiltrate.

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June 2015 Case of the Month

   Answer: Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT Lymphoma)

The gastric biopsy shows marked expansion of the lamina propria by a monomorphous lymphoid infiltrate.  Scattered lymphoepithelial lesions and destruction of the gastric pits is noted.  By immunohistochemistry, the infiltrate is CD20(+), CD3(-), CD5(-), CD10(-), Bcl6(-), Bcl2(+), CD43(-), and cyclin D1(-).  In addition, a CD138 stain highlights collections of plasma cells which show kappa light-chain restriction by immunohistochemistry.  These features are thus consistent with a MALT lymphoma of the stomach.  An H. pylori immunostain was negative in this case, though infection by this organism has a strong association with gastric MALT lymphoma.  Some studies have shown a lower incidence as well as detection rate of H. pylori as lymphoma evolves from gastritis.  Roughly 6-26% of gastric MALT lymphomas may show a t(11;18) translocation of the BIRC3 (formerly API2 gene) and MALT1 genes; however, chromosomal analysis or FISH testing were not performed in this case.  In general, MALT lymphomas behave in a biologically indolent manner.