Interdigitating Reticulum Cell Sarcoma

Interdigitating Reticulum Cell Sarcoma

Wesley O. Greaves, MD

L. Jeffrey Medeiros, MD

Cyril Fisher, MD, DSc, FRCPath

Interdigitating dendritic cell sarcoma subtotally replacing lymph node shows that the neoplasm tends to spare lymphoid follicles. The neoplasm was S100 protein(+).

Interdigitating dendritic cell sarcoma involving lymph node shows that the neoplastic cells are spindled and epithelioid with abundant eosinophilic cytoplasm. A mitotic figure is present image.



  • Interdigitating dendritic cell (IDC) tumor

  • Interdigitating dendritic reticulum cell sarcoma


  • Neoplastic proliferation of cells with immunophenotype similar to normal IDCs


Postulated Normal Cell Counterpart is IDC

  • Antigen-presenting cell involved in T-cell immunity

  • Derived from CD34(+) lymphoid/myeloid progenitor cell in bone marrow that homes to lymph node

  • Normally found in

    • T-cell regions of lymph node

    • Periarteriolar lymphoid sheaths

    • Interfollicular areas of extranodal lymphoid tissue

Concept of “Transdifferentiation”

  • Rare patients with histiocytic neoplasms also have clonally related B-cell lymphoma

    • Usually B-cell lymphoma precedes histiocytic neoplasm

      • IDC sarcoma and follicular lymphoma

      • Histiocytic sarcoma and follicular lymphoma

      • IDC sarcoma and chronic lymphocytic leukemia/small lymphocytic lymphoma

      • Histiocytic sarcoma and splenic marginal zone lymphoma

    • Histiocytic neoplasms associated with follicular lymphoma share

      • t(14;18)(q32;q21)/BCL2-IgH &/or identical IgH gene rearrangements

    • Histiocytic tumors and nonfollicular B-cell lymphomas share identical IgH gene rearrangements

  • B-cell lymphoma might transform to histiocytic phenotype via “transdifferentiation”

    • Possibly due to loss of key components of B-cell differentiation



  • Incidence

    • Very rare

  • Age

    • Most patients are adults; median: 6th-7th decade

    • Youngest patient reported was 2 years old

  • Gender

    • Male to female ratio = 1.2:1


  • Lymph node

    • Most commonly a single lymph node is involved

    • Cervical, axillary, or inguinal lymph node groups most often affected

  • Extranodal sites can be involved

    • Skin and soft tissue most common

    • Liver and spleen

    • Gastrointestinal tract, lung, kidney

    • Bone marrow is involved in < 20% of patients


Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Interdigitating Reticulum Cell Sarcoma

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