Lymphoma and plasma cell neoplasms
Small B cell lymphomas with a circulating component
Splenic diffuse red pulp small B cell lymphoma (SDRPL)


Topic Completed: 8 February 2019

Revised: 14 February 2019

Copyright: 2019, PathologyOutlines.com, Inc.

PubMed Search: Splenic diffuse red pulp small B cell lymphoma

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Cite this page: Hartsough E, Mroz P. Splenic diffuse red pulp small B cell Lymphoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lymphomasdrpl.html. Accessed February 18th, 2019.
Definition / general
  • Unclassifiable splenic mature B cell lymphoma variant characterized by diffuse infiltration of the splenic red pulp with small, monomorphous B lymphocytes
  • Bone marrow and peripheral blood are often also involved, in which the lymphocytes can adopt a villous morphology
Essential features
  • Provisional entity characterized as splenic B cell lymphoma / leukemia, unclassifiable, along with hairy cell leukemia variant (Swerdlow: WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th Edition, 2017)
  • Indolent disease course, often diagnosed at clinical stage IV disease (involvement of spleen, bone marrow and peripheral blood)
  • Microscopically characterized by small to intermediate sized B lymphocytes diffusely invading the red pulp cords
    • Intrasinusoidal involvement can be seen on bone marrow biopsy
    • Peripheral blood smear reveals villous cytology
  • Important to differentiate from hairy cell leukemia, hairy cell leukemia variant and splenic marginal zone lymphoma
Terminology
  • Provisional entity under splenic B cell lymphoma / leukemia, unclassifiable (WHO classification)
  • Splenic lymphoma with villous lymphocytes
  • SDRPL
  • SDRP SBCL
ICD coding
  • ICD-3: 9591/3 - splenic diffuse red pulp small B cell lymphoma
Epidemiology
  • Incidence:
    • Rare, < 1% of all non-Hodgkin lymphomas
    • 10% of splenic B cell lymphomas
  • Age: Usually > 40 years (median 65.5 - 77 years)
  • Sex: M > F (ratio varies between 1.6 - 2.4) (Discov Med 2012;13:253)
Sites
Clinical features
  • Massive splenomegaly is seen in most cases
  • Often presents with stage IV disease (blood and bone marrow involvement)
  • Splenic hilar lymph nodes are frequently reported (Haematologica 2010;95:1122)
  • B symptoms (rare)
  • Erythematous and pruritic skin papules (10% of cases) (Haematologica 2010;95:1122)
Diagnosis
  • Requires constellation of clinical features, peripheral blood smear, marrow and spleen histology, immunophenotyping and cytogenetics
  • Splenectomy is required for confirmation of diagnosis (Arch Pathol Lab Med 2014;138:1295)
Laboratory
Radiology description
  • Massive splenomegaly
Prognostic factors
  • Indolent but incurable disease
  • Must differentiate from similar diseases, as it has a good prognosis but is often resistant to conventional chemotherapy that is effective for hairy cell leukemia, hairy cell leukemia variant and splenic marginal zone lymphoma (Blood Res 2018;53:74)
  • Cases with mutations in NOTCH1, MAP2K1 and TP53 have been reported to have shorter progression free survival (Am J Surg Pathol 2016;40:192)
Case reports
Treatment
  • Splenectomy (first line treatment option)
  • No treatment (watch and wait)
  • Chemotherapy may be more chemotherapy resistant than hairy cell leukemia, hairy cell leukemia variant and splenic marginal zone lymphoma (Blood Res 2018;53:74)
  • Rituximab (Discov Med 2012;13:253)
Gross description
  • Diffusely enlarged spleen with a homogenous beefy red-brown cut surface
  • Wedge shaped subcapsular infarcts (Blood Res 2018;53:74)
Gross images

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Diffusely enlarged spleen

Microscopic (histologic) description
Microscopic (histologic) images

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Splenic red pulp infiltrate

Bone marrow infiltrate

Cytology description
  • Small to medium, monomorphic lymphocytes with round oval nuclei and compact, clumped chromatin
  • Occasionally distinct, small nucleoli
Peripheral smear description
  • Small villous lymphocytes with clumped chromatin and a smooth nuclear outline
  • Cytoplasm is basophilic with broad based cytoplasmic extensions in a polar distribution (Blood 2008;111:2253)
Peripheral smear images

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Neoplastic villous lymphocytes

Positive stains
Flow cytometry description
Molecular / cytogenetics description
  • Del 7(q), partial trisomy 3q, trisomy 18, del 17p reported (Blood 2008;111:2253)
  • Does not have BRAF V600E mutation
Differential diagnosis
  • There is overlap with other entities that primarily affect the spleen and display villous cytology (Blood Res 2018;53:74)
    • Splenic marginal zone lymphoma
      • Anemia and thrombocytopenia: present (autoimmune)
      • Monocytopenia: absent
      • Blood smear: tumor cells with polar villi and inconspicuous nucleoli
      • Spleen: micronodular pattern with white pulp replacement, marginal zone differentiation
      • CD25+, CD103 (variable), CD123- by flow; Annexin A1-, DBA-44 (variable) by IHC
      • Bone marrow: nodular interstitial and sinusoidal infiltrate
      • Genetic mutation: NOTCH2, VH1 / 2
      • Associated cytogenetic abnormality: del 7q, trisomy 3 (less common)
    • Hairy cell leukemia
      • Anemia and thrombocytopenia: present
      • Monocytopenia: present (characteristic)
      • Blood smear: present with reniform or oval nuclei, circumferential long villi, inconspicuous nucleoli
      • Spleen:
        • Diffuse infiltrate in red pulp cords, effaced white pulp, formation of blood lakes
        • TRAP+
      • Bone marrow: dense infiltrate, fibrosis
      • CD25+, CD103+, CD123+, Annexin A1+, DBA-44+
      • Genetic mutation: BRAF V600E mutation in ~100%
      • Associated cytogenetic abnormality: del 13q, del 7q (uncommon)
      • Treatment: purine analogs, rituximab
    • Hairy cell leukemia variant
      • Anemia and thrombocytopenia: present
      • Monocytopenia: absent (leukocytosis with lymphocytosis and normal monocyte count)
      • Blood smear: tumor cells with abundant circumferential villi and prominent nucleoli
      • Spleen:
        • Red pulp involved, blood lakes uncommon
        • Effaced white pulp with absent white pulp follicles
        • TRAP-
      • Bone marrow: interstitial, sinusoidal infiltrate
      • CD25-, CD103+, CD123- by flow; Annexin A1-, DBA-44+ by IHC
      • Genetic mutation: MAP2K1
      • Associated cytogenetic abnormality: del 17p(TP53)
      • Treatment: partial response to purine analogs; splenectomy
Board review question #1
A 60 year old man presents with abdominal discomfort and generalized weakness. CT of the chest / abdomen / pelvis reveals massive splenomegaly. Splenectomy demonstrates a monomorphic diffuse infiltration of the red pulp with effacement of the white pulp. Peripheral blood smear is as follows (see image). Immunohistochemistry is positive for CD20 and DBA-44 and negative for CD25, CD103, CD123 and Annexin A1. What is the most likely diagnosis?



  1. Hairy cell leukemia
  2. Hairy cell leukemia variant
  3. Splenic diffuse red pulp small B cell lymphoma
  4. Splenic marginal zone lymphoma
Board review answer #1
C. Splenic diffuse red pulp small B cell lymphoma

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Board review question #2
What is the most common treatment for splenic diffuse red pulp small B cell lymphoma?

  1. Chemotherapy
  2. Immunotherapy
  3. Radiation
  4. Splenectomy
Board review answer #2
D. Splenectomy

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