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Case 75 - Discussion

Hematopathology Case

CD43 CD79a
CD20 Lambda
The minor salivary gland lesion shows nodular growth pattern, which is composed of a mixed population of lymphoid cells, including small mature lymphocytes, monocytoid B-cells, and plasmacytoid cells. Prominent vascular proliferation and granulomatous reaction are present. Marked intraepithelial monocytoid cell infiltration is noted (lymphoepithelial lesions) in multiple foci. The tumor also shows abundant plasmacytic differentiation, with kappa light chain restriction.

Extranodal Marginal Zone Lymphoma (MALT Lymphoma)

  • Rarely arise from native MALT, usually from acquired MALT

  • Histology:

    • Heterogeneous small B cells: marginal zone (centrocyte-like) cells, monocytoid cells, small lymphocytes, and scattered immunoblast and centroblast-like cells

    • Often with plasma cell differentiation, which may mimic plasmacytoma

    • Reactive follicles with colonization of germinal centers

    • Lymphoepithelial lesions often present

  • Gastric MALT lymphoma: H. pylori in > 90% cases, eradication of H. pylori results in regression of lymphoma in 75% of cases

  • Immunoprofile:

    • Positive: CD20, CD79a, CD21, CD35, IgM

    • CD43 positive in 50% cases

    • Negative: CD5, CD23, CD10, IgD

  • Prognosis: among the most indolent of all lymphomas, good prognosis regardless of stage, 5-10 year overall survival rates > 80%