AUL

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What features must be met to diagnose acute undifferentiated leukaemia This is a difficult area where the diagnosis of acute leukaemia is suspected but no criteria for lineage assignment can be made i.e. the cases do not meet any of the criteria for myeloid, B-lymphoid, or T-lymphoid lineage given above. An important aspect of this group is to exclude the possibility of rare entities that can mimic AML: these include non-haemaotopoietic neoplasm and blastic plasma cell dendritic neoplasm.
Requirement 1
Required No lineage assignment can be made based on single lineage-defining myeloid, B-lymphoid or T-lymphoid msrkers i.e. do not express MPO, CD3, strong CD19, cyCD22 or cyCD79a
Requirement 2
No more than one lineage-associated (but not lineage-defining marker) for any lineage should be expressed
Requirement 3
Markers mainly associated with the primitive nature of leukaemic cells do not allow lineage assignment (e.g. CD34, HLA-DR, TdT, CD7, CD38) and are frequently seen in undifferentiated acute leukaemia
Requirement 4
It is essential that other conditions that may resemble undifferentiated acute leukaemia are excluded: these may particu;arly include: acute megakaryocytic leukaemia, non haematopoietic tumours, blastic plasma cell dendritic neoplasm, and rarely plasma cell leukaemias. In each case this may require consideration of the wider context of the clinical history and marker pattern.