MYELOID/NK
CELL PRECURSOR ACUTE LEUKEMIA (the category myeloid/NK
cell precursor acute leukemia is defined as a CD7+56+,
sCD3-, myeloperoxidase-neoplasm with lymphoblastic morphologyref)
is poorly defined and likely arises from an early multipotential myeloid/NK
cell. Extramedullary disease is more prominent than usually seen in AML
with nodal disease in 87%, mediastinal involvement in 20% and skin involvement
in approximately 10%
Aetiology : EBV has not been detected
Laboratory examinations :
cytomorphology : the tumor cells have a lymphoblastic appearance (L2 morphology)
and are agranular
immunophenotype : CD2+, surface CD3-, CD4+/-,
CD5-/+, CD7+, CD11b+, CD11c+,
CD13+ and/or CD33+, myeloperoxidase-/+,
CD56+, CD16-, CD57-, CD34+ref.
Care should be taken in making a diagnosis of myeloid/NK-cell precursor
acute leukemia as 13-41% of acute
myeloid leukemias
can express CD56 (Iizuka Y, Aiso M, Oshimi K, et al. Myeloblastoma formation
in acute myeloid leukemia. Leu Res.1992;16:665–671)ref.