Histiocytic Sarcoma

Histiocytic Sarcoma

Aaron Auerbach, MD, PhD

Histiocytic sarcoma at low magnification shows a diffuse, dermal-based sheet-like proliferation of enlarged, undifferentiated-appearing cells at this power.

High magnification of histiocytic sarcoma shows sheets of markedly enlarged and atypical cells image with abundant cytoplasm, enlarged nuclei with prominent nucleoli, and scattered mitotic figures image.



  • Histiocytic sarcoma (HS)


  • Extramedullary monocytic tumor

  • Malignant histiocytosis

  • True histiocytic lymphoma


  • Malignant tumor of mature histiocytes

    • Neoplasms associated with acute monocytic leukemia are excluded

      • Are now classified as monocytic sarcoma



  • Idiopathic

    • Sometimes associated with germ cell tumors

    • Also can be associated with lymphoma, leukemia, or myelodysplastic syndrome

Postulated Normal Counterpart

  • Mature histiocyte



  • Incidence

    • Extremely rare tumor

  • Age

    • Mostly in adults

      • Median age = 52 years old

      • Rare in children

  • Gender

    • Approximately equal male:female ratio

  • Ethnicity

    • No known ethnic predilection


  • Most cases are extranodal

    • Skin, gastrointestinal tract, and soft tissue most common

  • Lymph node less common


  • Often a single painless mass

    • B symptoms common

  • Skin

    • Variable presentation

      • Can be seen as a rash, a single lesion, or multiple lesions (disseminated)

  • Gastrointestinal tract

    • Abdominal pain

    • Intestinal obstruction

  • Bone marrow

    • Focal/patchy bone marrow involvement is considered HS

      • Diffuse bone marrow involvement is currently classified as acute monocytic leukemia

Laboratory Tests

  • Cytopenias in some patients

    • Thrombocytopenia is most common

Natural History

  • Some patients develop both histiocytic tumors and lymphoid tumors

    • Lineage promiscuity (a.k.a. transdifferentiation)

    • Both tumors share molecular findings

      • HS can have t(14;18)(q32;q21)

      • HS can have clonal IgH gene rearrangements

      • Identical IgH rearrangements or BCL2 gene breakpoints in same patients with HS and B-cell lymphoma


  • Surgical approaches

    • Surgical excision with wide margins

  • Adjuvant therapy

    • Chemotherapy and radiation therapy

      • Non-Hodgkin lymphoma protocols (i.e., CHOP)

      • Acute leukemia protocols


  • Low-stage (localized) lesions may be less clinically aggressive

  • High-stage lesions (multiple lesions, systemic disease, recurrences) resistant to adjuvant therapy

    • 80% of patients die of disease


General Features

  • Skin with rash or tumor nodule

    • 1 or more firm lesions


Histologic Features

  • Skin

    • Dermal and subcutaneous infiltrate with infiltrative borders

    • Spares epidermis, separated by grenz zone

  • Lymph node

    • Usually diffuse effacement of lymph node architecture

    • Focal involvement is often in paracortex

    • Rare tumor is seen in sinuses

  • Hemophagocytosis, sometimes

    • Emperipolesis in some cases

  • Mitotic figures

  • Inflammatory background

    • Often prominent

      • Reactive T cells, plasma cells, eosinophils

      • Especially in HS of central nervous system

Cytologic Features

  • Neoplastic cells, large and noncohesive

    • Nuclei

      • Usually epithelioid

      • Rarely spindle-shaped

      • Often highly pleomorphic cells, sometimes monomorphic

      • Vesicular chromatin

      • Nucleoli, prominent sometimes

      • Multinucleated cells can be seen

    • Cytoplasm is abundant

      • Eosinophilic

      • Cytoplasmic vacuoles sometimes

      • Xanthomatous appearance sometimes

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Histiocytic Sarcoma

Full access? Get Clinical Tree

Get Clinical Tree app for offline access
%d bloggers like this: