Acute leukemia of ambiguous lineage (ALAL) was a subtype established in the 2016 WHO classification revision. It is a very rare leukemia, that is further subdivided into five possible subgroups, partially based on chromosomal analysis.
ALAL patients present with an acute leukemia, but a specific lineage can not be assigned.
Some types of ALAL are immature hematopoietic neoplasms that show no differentiation into lymphoid or myeloid lines (AUL), whereas other types exhibit markers of both AML and ALL. The latter are referred to as mixed phenotype acute leukemia (MPAL).
The image to the right shows a case of ALAL. The arrow points to hypolobate neutrophils, emphasizing how unusual some of these cases can be.
When immunophenotyping these leukemias, AUL lacks T-cell specific, B-cell specific, and myeloid specific markers. MPAL, on the other hand, shows various immunophenotypes.
There are no clinical features that are specific to ALAL. but rather have signs and symptoms similar to AML and/or ALL. ALAL does generally carry a poor prognosis.
13. Moraveji, S et al. “Acute leukemia of ambiguous lineage with trisomy 4 as the sole cytogenetic abnormality: A case report and literature review.” Leukemia research reports vol. 3,2 33-5. 2 May. 2014, doi:10.1016/j.lrr.2014.04.003