Anatomic Pathology: Hematopathology

952) The lymphoid infiltrate shown in this gastric biopsy has the following immunophenotype: CD20 positive, CD43 positive, Bcl-2 positive, CD5 negative, and lambda positive. Which of the following microorganisms has been implicated in the pathogenesis of this lymphoma?

• The photomicrograph shows a gastric gland infiltrated by lymphoid cells forming a “lymphoepithelial lesion.” Lymphoepithelial lesions with lymphoid infiltrates showing a CD20 positive, CD43 positive, CD5 negative, and Bcl-2 positive phenotype and light chain restriction are characteristic of extranodal marginal zone lymphoma of mucosa associated lymphoid tissue (MALT-type). Helicobacter pylori infection is implicated in the cause of MALT lymphomas of the stomach.

• An etiologic role has been proposed for Borrelia burgdorferi infection in cutaneous marginal zone lymphoma (D). Mycobacterium avium complex (A), Streptococcus suis (B), and Corynebacterium amycolatum microorganisms (E) are not known to play an etiologic role in extranodal marginal zone lymphomas.

• Regression of MALT lymphoma of the stomach is sometimes seen with antibiotic treatment for H. pylori.

Swerdlow SH, Campo E, Harris NL, et al: WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues.Lyon, France: IARC, 2008.

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