Hematogenous neoplasms
Marginal zone B cell lymphoma (splenic marginal zone lymphoma - SMZL)

Author: Jaleh Mansouri, M.D. (see Authors page)

Revised: 6 March 2018, last major update April 2013

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Marginal zone B cell lymphoma[TIAB] spleen

Cite this page: Mansouri, J. Marginal zone B cell lymphoma (splenic marginal zone lymphoma - SMZL). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/spleenmarginalzone.html. Accessed March 21st, 2018.
Definition / general
  • Most common splenic low grade B cell lymphoma; affects middle aged and elderly patients
  • Usually disseminated (as opposed to MALT lymphoma) with splenomegaly and left upper quadrant pain, paratrabecular marrow involvement in 75% causing anemia, involvement of peripheral blood, liver and often splenic hilar lymph nodes but no peripheral nodal involvement unless it transforms
  • Usually indolent (5 year survival of 65%) but 13% transform, possibly related to 7q deletion (Am J Surg Pathol 2001;25:1268, Hum Pathol 1999;30:1153)
  • Note: cases with plasmacytic differentiation often present with monoclonal serum disorders and autoimmune disorders, including hemolytic anemia; may have Waldenström macroglobulinemia; are similar otherwise to nonplasmacytic cases (Am J Surg Pathol 2000;24:1581)
  • Includes splenic lymphoma with villous lymphocytes (older men, massive splenomegaly with atypical lymphocytes with cytoplasmic villous projections localized to one pole of cell present in peripheral blood, TRAP-, CD103-, HC2-)
  • Marginal zone: light zone surrounding splenic follicles; contains postfollicular center memory B cells derived after stimulation of recirculating cells from T cell dependent antigen
Case reports
Gross description
  • Enlarged spleen with multiple small, gray-white nodules
Gross images

Images hosted on other servers:

Markedly enlarged spleen

Microscopic (histologic) description
  • Marginal zone, biphasic or diffuse red pulp variants (see note)
  • Massive splenic involvement, with infiltration of small atypical lymphocytes in mantle zone and medium lymphocytes with pale cytoplasm and oval clear nucleus in marginal zone, leading to mixed mantle zone and marginal zone involvement pattern; variable follicular colonization but definite increase in white pulp
  • Cells are centrocyte-like, monocytoid (easily recognized with imprints) or lymphoplasmacytic; < 20% immunoblasts; regressed germinal centers; biphasic pattern consists of white pulp central core of small lymphocytes surrounded by peripheral rim of marginal zone-like lymphocytes; may involve red pulp also; intrasinusoidal infiltration of bone marrow is a relatively specific finding
  • Note: diffuse red pulp variant was placed in a provisional category (splenic diffuse red pulp small B cell lymphoma) in the 2008 WHO lymphoma classification (Curr Opin Oncol 2011;23:441); can overlap with hairy cell leukemia variant, which is DB.44+, IgG+, IgD-; other lymphomas not fulfilling criteria for provisional or established lymphoma classifications are classified as splenic B cell lymphoma / leukemia, unclassifiable
  • Lymph nodes: effaced, replaced by nodular infiltrate with preservation of sinuses; nodules have reactive follicular center surrounded by broad zone of small lymphocytes, partially infiltrated or totally replaced by small lymphocytes with pale cytoplasm (Am J Surg Pathol 1997;21:772)
Microscopic (histologic) images

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Prominent white pulp

Various images

Bone marrow biopsy

Cytology description
  • Peripheral smear: scant cytoplasm and cleaved nucleus; confirm neoplastic with flow cytometry
Positive stains
Negative stains
Molecular / cytogenetics description
  • Clonal rearrangements of IgH and IgL are common; often gains in chromosomes X, 3, 18 and losses in 6q and 7q31-32 (40%) (Mod Pathol 2003;16:1210); no t(11;18) translocations (API2-MALT1) that are associated with MALT lymphoma
  • Underexpression of miRNAs at 14q32-31 (Mod Pathol 2013;26:889)
Differential diagnosis
Additional references