acute myeloid leukemia, 11q23 (MLL) abnormalities

Introduction

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

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

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

Clinical manifestations

• disseminated intravascular coagulation
• extramedullary tissue infiltration or monocytic sarcomas

More general terms

• acute myeloid leukemia (AML)