Splenic Marginal Zone Lymphoma (SMZL)
Splenic lymphoma with circulating villous lymphocytes (SLVL)
Epidemiology:
- Rare
- May account for most cases of otherwise
unclassifiable chronic lymphoic leukemias that are CD5-
- > 50 years (most)
- HCV association in South Europe
Common sites:
- Spleen
- Splenic hilar lymph nodes (often)
- Not peripheral lymph nodes (extremely uncommon)
- Bone marrow (often)
- Peripheral blood (often)
- NOT Extranodal involvement
(extremely uncommon)
Gross features:
Histologic features:
- Small lymphocytic infiltration surrounding and
replacing splenic white pulp germinal centres
- Effacing the follicle mantle commonly
- Merging with a peripheral (marginal) zone of
larger cells including scattered transformed blasts
- More dispersed chromatin
- Abundant pale cytoplasm resembling marginal
zone cells
- Infiltration of the red pulp by both small and
larger cells (always)
- Epithelioid histiocytes
maybe
- Plasmacytic
differentiation maybe
- Clusters of plasma cells maybe
- Lymph node (splenic hilar):
- Sinus dilated
- Lymphoma cells surround and replace germinal centres
- Without formation of a distinct “marginal” zone
often
- BM:
- Nodular interstitial infiltrate
- Surrounding reactive follicles (occasionally)
- Intrasinusoidal lymphoma cells (CD20 highlights)
- Peripheral blood (may be involved)
- Villous lymphocytes (short polar villi)
(usually but not always)
Immunophenotype:
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Marker:
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Sensitivity:
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Specificity:
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sIgM
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sIgD
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Usually
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CD20, 79a
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CD5 (neg)
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Infrequently positive
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CD10 (neg)
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CD23 (neg)
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CD43 (neg)
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Cyclin D1 (neg)
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CD103 (neg)
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Usually
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Annexin A1 (neg)
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Expressed in
HCL
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Ki-67
(distinctive targetoid pattern)
(germinal
centre if present, and marginal zone)
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Molecular features:
- 7q21-q32 loss (40%) (poor prognosis maybe)
- CDK6 dysregulation (7q21)
- Trisomy 3q
- Absence of BCL2 rearrangement, t(11;14) (MALT1?)
- NOT associated with t(11;18)
- TP53 mutation (poor prognosis maybe)
- Unmutated
IGHV gene may be associated with poor prognosis
Other features:
- presents with splenomegaly
- autoimmune thrombocytopenia (sometimes
accompanied by)
- anemia (sometimes)
- indolent course
- transformation to large B-cell lymphoma may
occur
- poor response to chemo often
- haematologic response to splenectomy typically, with long-term survival
- large tumour mass may
be adverse prognostic factor
- small monoclonal serum protein (1/3)
- hypergammaglobulinemia is uncommon
References:
- Swerdlow
et al. WHO Classification of Tumours of Haematopoietic
and Lymphoid Tissues (2008)