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Case 106 - Discussion

Hematopathology Case

 

Diagnosis: Splenic Marginal Zone Lymphoma

This case showed predominantly larger marginal zone-like cells with minimal central smaller tumor cells.

 

Splenic Marginal Zone Lymphoma

CLINICAL FEATURES

  • Most patients > 50 years old, M=F.

  • Locations: spleen, splenic hilar lymph nodes, bone marrow and peripheral blood, maybe liver. Rarely extranodal or peripheral lymph nodes.

  • Autoimmune thrombocytopenia, anemia, peripheral blood with villous lymphocytes.

  • Cases with plasmacytic differentiation often present with monoclonal serum disorders and autoimmune disorders, including hemolytic anemia.

  • Paraproteinemia (usually IgM) in 10-28% of cases.

MICROSCOPIC FINDINGS

  • Peripheral blood:

    • Cell size: small

    • Nucleus: round, oval, or slightly irregular

    • Chromatin: dense

    • Nucleolus: inconspicuous

    • Cytoplasm: moderately abundant, polar projections

  • Spleen:

    • Mixed mantle-zone and marginal-zone involvement: the tumor cells in the center are small and atypical with effacement of the normal mantle zone and colonization of the germinal center; the tumor cells in the peripheral (the marginal zone) are medium in size with pale cytoplasm and oval nucleus with dispersed chromatin

    • The tumor cells are centrocyte-like, monocytoid, lymphoplasmacytic, and < 20% immunoblasts

    • Always involves red pulp

  • Bone marrow:

    • Almost always involved

    • Nodular and characteristic sinusoidal infiltration, better highlighted by CD20 staining

    • Often with plasmacytic differentiation

IMMUNOPHENOTYPE

  • Positive: CD20, CD79a, IgM,  and IgD (dim)

  • Negative: CD5, CD10, CD23, CD43, BCL1, CD103, Annexin A1 and DBA.44

DIFFERENTIAL DIAGNOSES

  • CLL/SLL: less cytoplasm, more regular nuclei, more condensed chromatin, proliferative center, CD5+, CD23+.
  • Mantle cell lymphoma: CD5+, BCL1+.
  • Hair cell leukemia: red pulp involvement, blood lake, more open chromatin, circumferential villi, CD103+, annexin A1+.

CYTOGENETIC STUDIES

  • Del(7q31-32 ) of CDK6 gene may be associated with transformation.
  • No t(11;18).

TREATMENT AND PROGNOSIS

  • Indolent even with bone marrow involvement.
  • Del(7q31-32 ) and unmutated IGHV gene are associated with unfavorable prognosis.

REFERENCES: WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, Fourth Edition. 2008.