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Case 234 - Discussion

Hematopathology Case





Blastic Plasmacytoid Dendritic Cell Neoplasm

  • Onset: skin involvement first and then dissemination (90%), or acute leukemia (10%)

  • At presentation, often with lymphadenopathy (20%), spleen (40-60%), bone marrow (40-90%)

  • Associated with CMML or AML in 15-20% cases

  • Morphology:

    • Diffuse, dense, monomorphic infiltrate

    • Blastic morphology: medium-sized cells, single nuclei with a variably irregular contour; fine chromatin; single or multiple eosinophilic nucleoli, when present; scant and gray-blue cytoplasm, devoid of cytoplasmic azurophilic granules

    • Absence of necrosis and angioinvasion

    • Cytology: medium-sized cells with blastic features, but may resemble mature lymphomatous cells or atypical monocytes

    • Skin: infiltrate dermis and subcutaneous fat, spare epidermis

    • Lymph nodes: involves interfollicular areas and medulla, spare follicles

    • Bone marrow: subtle interstitial infiltrate or massive localization; dysplastic

  • Immunoprofile:

    • Positive: CD45RA, CD4, CD56, CD123, TCL1, BDCA-2, CD2AP, BCL11a;

    • Maybe positive: CD2, CD7, CD33, and TdT

    • Negative: CD34, CD117, T cell markers (CD3, CD5, LAT, TCR-AB, TCR-GD), B cells (CD19, CD20, PAX5), NK cells (CD16, TIA-1, perforin), and myelomonocytic cells (myeloperoxidase, lysozyme, CD11c, CD14, CD163, esterases)

  • Germline configuration of B-cell and T-cell receptor genes

  • Negative for LMP-1 and EBER

  • No specific chromosomal aberrations

Reference: Hematopathology: Expert Consult. 2010