acute myeloid leukemia, 11q23 (MLL) abnormalities

usually associated with monocytic features Epidemiology: - ~5-6% AML cases - more common in children - two subgroups with high frequency of 11q23 abnormality and AML: - AML in infants - therapy related AML, usually after topoisomerase II inhibitors Genetics: - MLL gene on chromosome 11q23 involved in different translocations: - t(9;11)(p21;q23) and t(11;19)(q23;p13.1)/ t(11;19)(q23;p13.3) most common translocations in childhood AML Microscopic Pathology: - often monocytic or myelomonocytic leukemias - monoblasts and promonocytes predominate Immunophenotype: - monoblasts & promonocytes usually strongly positive for non-specific esterase reaction - myeloid antigens CD13, CD33 expression variable - monoblasts: CD34 negative CD4, CD14, CD11b, CD11c, CD36, CD64, lysozyme positive Clinical manifestations: - disseminated intravascular coagulation - extramedullary tissue infiltration or monocytic sarcomas

References

WHO Classification Tumours of Haematopoietic and Lymphoid Tissues. IARC Press 2001