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9 - Grade/differentiation unknown, not stated, or not applicable
This leukemia meets criteria for assignment to both B and myeloid lineage as in 9807 (mixed phenotype acute leukemia with t(v;11q23) MLL rearranged), but the blasts lack the genetic abnormalities seen in 9807. Most cases have blasts with no distinguishing features, morphologically resembling ALL, or have dimorphic populations with one resembling lymphoblasts and the other resembling myeloblasts.
(This code is effective for cases diagnosed 2010 and later. For cases diagnosed prior to 2010 see code 9801/3.) This leukemia is very rare; probably accounts for about 1% of leukemias. It is more common in adults, but is also seen in children. There are no unique clinical features for this leukemia. Although the leukemia meets the criteria for both B and myeloid lineages, the blasts lack the B and myeloid genetic abnormalities.
Definitive Diagnostic Methods
Bone marrow biopsy AND
Numerical abnormalities including near tetraploidy