-
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
|
