Lymphoma and plasma cell neoplasms
Mature B cell neoplasms: mantle cell lymphoma
In situ mantle cell neoplasia

Senior Author: Kyle Bradley, M.D., M.S.
Editor-in-Chief: Debra Zynger, M.D.
Cameron Neely, M.D.
Kyle Bradley, M.D., M.S.

Topic Completed: 21 August 2019

Revised: 21 August 2019

Copyright: 2019, PathologyOutlines.com, Inc.

PubMed Search: in situ mantle cell neoplasia [title]

Cameron Neely, M.D.
Kyle Bradley, M.D., M.S.
Page views in 2019 to date: 245
Cite this page: Neely C, Bradley K. In situ mantle cell neoplasia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lymphomaisMCN.html. Accessed September 20th, 2019.
Definition / general
  • Cyclin D1 positive B cells with CCND1 rearrangements restricted to the mantle zones of reactive appearing lymphoid tissue (Blood 2016;127:2375)
Essential features
Terminology
  • Previously “in situ mantle cell lymphoma,” “in situ involvement by mantle cell lymphoma-like cells,” or “mantle cell lymphoma-like B cells of uncertain / undetermined significance” (Semin Diagn Pathol 2018;35:76)
Epidemiology
Sites
Pathophysiology
  • t(11;14) IGH-CCND1 translocation results in overexpression of cyclin D1 and dysregulation of the cell cycle (J Clin Invest 2012;122:3416)
  • Low levels of B cells with t(11;14) translocation have been identified in peripheral blood of healthy individuals (Mod Pathol 2012;25:1629)
  • Cyclin D1 positive B cells with CCND1 rearrangements may colonize the mantle zones of lymphoid follicles (Blood 2016;127:2375)
  • Risk of progression is very low (Blood 2016;127:2375)
Etiology
  • Unclear
Clinical features
Radiology description
  • No specific radiologic findings
Case reports
Treatment
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Kyle Bradley, M.D.
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Mantle zone and interfollicular involvement

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Early lymph node involvement by mantle cell lymphoma


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Follicular lymphoma with concurrent in situ mantle cell neoplasia

Positive stains
Negative stains
Flow cytometry description
  • Clonal in situ mantle cell neoplasia cells may be detected by flow cytometry but this may require careful gating strategies due to the presence of nonclonal B cells present in involved lymph nodes
  • Phenotype is indistinguishable from typical mantle cell lymphoma:
    • Positive for B cell markers (CD19, CD20, CD22), CD5, FMC7 and kappa or lambda surface immunoglobulin light chain
    • Negative for CD10, CD11c, CD23, CD103 and CD200
Molecular / cytogenetics description
Sample pathology report
  • Lymph node, right axilla, excision:
    • In situ mantle cell neoplasia (see comment)
    • Comment: The H&E stained sections show morphologic features consistent with a benign lymph node with follicular hyperplasia. A cyclin D1 immunohistochemical stain demonstrates cyclin D1 positive cells confined to the inner mantle zones of lymphoid follicles without mantle zone expansion. These findings are consistent with in situ mantle cell neoplasia. In situ mantle cell neoplasia typically follows an indolent course; however, rare cases may progress to overt mantle cell lymphoma.
Differential diagnosis
Board review question #1
    In situ mantle cell neoplasia is characterized by which of the following translocations?

  1. t(9;22) BCR-ABL1
  2. t(11;14) IGH-CCND1
  3. t(14;18) BCL2-IGH
  4. t(8;14) MYC-IGH
Board review answer #1
B. The characteristic translocation of in situ mantle cell neoplasia is t(11;14) IGH-CCND1, resulting in overexpression of cyclin D1.

Reference: In situ mantle cell neoplasia

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Board review question #2
    In a lymph node biopsy, which of the following features supports a diagnosis of in situ mantle cell neoplasia?

  1. Mantle zones expanded by cyclin D1 positive B cells
  2. Cyclin D1 positive B cells extending into the interfollicular region
  3. Monoclonal proliferation of BCL2 positive B cells confined to germinal centers
  4. Preserved lymphoid architecture
Board review answer #2
D. In situ mantle cell neoplasia is characterized by cyclin D1 positive B cells restricted to the mantle zone of reactive appearing lymphoid tissue. Lymphoid architecture is preserved. Expansion of the mantle zone, complete replacement of the mantle zone or significant extension into the interfollicular region or germinal center by cyclin D1 positive B cells warrants a diagnosis of mantle cell lymphoma rather than in situ mantle cell neoplasia. A monoclonal proliferation of BCL2 positive B cells confined to germinal centers in a hyperplastic appearing lymphoid follicle is consistent with in situ follicular neoplasia.

Reference: In situ mantle cell neoplasia

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Board review question #3
    Which of the following is true of in situ mantle cell neoplasia?

  1. Usually progresses to overt mantle cell lymphoma
  2. Characterized by aggressive behavior
  3. May be seen in extranodal locations
  4. Peripheral blood involvement is not permitted
Board review answer #3
C. In situ mantle cell neoplasia is a rare finding that is most commonly seen in lymph nodes but may be seen in extranodal locations. Peripheral blood involvement is permitted. It is typically a stable disease with indolent behavior and rare progression to overt mantle cell lymphoma.

Reference: In situ mantle cell neoplasia

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