Back to Homepage

Case 51 - Discussion

Hematopathology Case

 

  • Histopathology: Tumor cells are arranged in fascicles, whorls or storiform patterns. They are monomorphic and have round or short spindle nuclei with vesicular chromatin and prominent nucleoli. The cytoplasm is moderate to abundant and pale eosinophilic. There is no increase in mitotic figures.  Admixed with the spindle cells are small lymphocytes, occasional eosinophils and plasma cells. growth pattern with mixed reactive small lymphocytes. The tumor cells

  • Immunostains:

    • Positive: CD21, CD35 and clusterin

    • Negative: Pan-CK, CK-LMW, CD45, chromogranin, synaptophysin, and CD57

  • Diagnosis

    • Follicular dendritic cell sarcoma

Follicular Dendritic Cell Sarcoma

  • 10%-20% of cases associated with Castlemanís disease, mostly hyaline vascular type

  • Histology:

    • Storiform or whorled bundles of spindle cells with admixture of lymphocytes

    • Spindle cells: ovoid to elongated bland nuclei, vesicular or granular chromatin, thin nuclear membrane, and a small nucleolus; moderate eosinophilic cytoplasm, and indistinct cell borders

  • Inflammatory pseudotumor variant:

    • Location: spleen and liver

    • Less spindle cells with abundant lymphocytes and plasma cells

    • Spindle cells with viable atypia and often prominent nucleoli

    • Focal and weak expression of follicular dendritic cell markers

    • EBV+ in most cases

  • Immunophenotype:

    • Positive: CD21, CD23, CD35, clusterin, fascin

    • Negative: S100, CD1a, HMB45, MSA, desmin, cytokeratin

  • Electron Microscope:

    • Numerous long, thin cytoplasmic processes

    • Mature desmosomes

    • No Birbeck granules

  • Differential Diagnosis

    • Interdigitating dendritic cell sarcoma

    • Inflammatory pseudotumor: often in lung and bladder, proliferation of myofibroblasts and fibroblasts with distinct cell borders, myxoid background with mixed inflammatory cells, SMA+, MSA+, ALK+ (40%), S100-, CD21/CD23/CD35-

    • Metastatic melanoma: particularly spindle cell variant, S100+

     

     

    Follicular dendritic

    cell sarcoma

    Interdigitating

    dendritic cell sarcoma

    Histiocytic

    Sarcoma

    Langerhans Cell Histiocytosis

    Origin

    Mesenchymal

    Monocyte-macrophage

    Monocyte-macrophage

    Monocyte-macrophage

    Electron microscopy

    Numerous cytoplasmic processes & desmosomes

    Complex interdigitating cellular junctions

     

    Birbeck granule

    CD1a

    +

    CD3

    CD20

    CD21

    +

    CD23

    +

    CD35

    +

    CD45

    +/− (weak)

    +

    +/−

    CD68

    +/−

    +/−

    +

    +

    CD163

    +/−

    +

    +

    +

    S100

    +

    +/−

    +

    Langerin

    +

    HMB-45

    Lysozyme

    +

    +

    +/−