Acute Myeloid Leukemia with t(9;11)(p22;q23), MLLT3-MLL

Acute Myeloid Leukemia with t(9;11)(p22;q23), MLLT3-MLL

Kaaren K. Reichard, MD

This bone marrow aspirate smear demonstrates the classic cytology of AML with t(9;11). The cells are monoblasts with an abundant rim of cytoplasm containing MPO-negative azurophilic granules.

This karyogram shows t(9;11)(p22;q23) image in a case of AML with monocytic differentiation. At the molecular level, MLL (11q23) and MLLT3 are aberrantly juxtaposed, resulting in a chimeric fusion protein.



  • AML with t(9;11)


  • Acute myeloid leukemia with MLL/11q23 abnormality


  • Acute myeloid leukemia with t(9;11)(p22;q23) or variant &/or molecular evidence of MLL-MLLT3 fusion

  • Strong association with AML M5 and M4 subtypes (FAB classification)

  • Usually AML with monoblastic/monocytic differentiation

  • Blasts/blast equivalents ≥ 20%

    • Monoblasts and promonocytes



  • May occur at any age

    • ˜ 5-20% of pediatric AML

    • ˜ 4-5% of adult AML

  • Rare cases may originate from pre-B-cell harboring MLL-MLLT3 fusion


  • Mixed lineage leukemia gene

  • Human homologue of the trithorax gene in Drosophila

  • Encodes DNA-binding protein

    • Transcription regulatory factor (e.g., HOX genes)

    • Methylates histone H3

    • Chromatin remodeling

    • Plays major role in hematopoiesis


  • a.k.a. AF9

  • Involved in erythroid and megakaryocytic production

  • Involved in regulation of transcription



  • Leukocytosis

  • Blood abnormality, NOS

  • Monocytosis

  • Extramedullary disease

    • Skin involvement, CNS symptoms, gingival hyperplasia

  • Disseminated intravascular coagulation (DIC)


  • Drugs

    • Chemotherapy


  • Intermediate compared with other AMLs

  • Better than AMLs with other MLL (non MLLT3) rearrangements

  • Minimal residual disease monitoring

    • Early achievement of molecular negativity for MLL-MLLT3

      • May portend longer remission status

    • Increasing MLL-MLLT3 transcripts

      • May herald early disease relapse


Predominant Pattern/Injury Type

  • Diffuse

Predominant Cell/Compartment Type

  • Blast

  • Hematopoietic stem cell


  • Peripheral blood

    • Variable WBC count

    • Often leukocytosis

    • Anemia

    • Thrombocytopenia

    • Circulating monoblasts and promonocytes

      • Usually > 20% of WBCs

    • Circulating myeloid blasts

      • Some cases show variable, usually small (< 5-10%) population of otherwise typical myeloblasts

    • Monoblasts

      • Large

      • Round nuclear contours

      • Fine chromatin

      • Prominent nucleolus

      • Abundant variably basophilic cytoplasm

      • Cytoplasmic azurophilic granules (MPO negative)

      • No Auer rods

    • Promonocytes

      • Intermediate to large

      • Smaller, variably prominent nucleoli

      • Abundant lightly basophilic/bluer cytoplasm

      • Gently lobulated nuclei with delicate nuclear folding

      • More even/dispersed chromatin pattern than typical monocyte

    • No significant granulocytic or platelet dysplasia

  • Bone marrow aspirate smears

    • Hypercellular

    • Usually sheets of monoblasts and promonocytes

      • Comprise > 80% of marrow nucleated cells

    • No significant background dysplasia

    • No significant basophilia or eosinophilia

  • Bone marrow core biopsy

    • Hypercellular

    • Predominant population of blasts/promonocytes

    • May see scattered residual hematopoietic elements

    • No significant, disease-related bony changes

Extramedullary Disease

  • Myeloid sarcoma

  • Sites most affected: Skin, gingiva, CNS



  • Myeloperoxidase (MPO)

    • Typically negative in monoblasts and promonocytes

  • Nonspecific esterase (NSE) (α naphthyl butyrate esterase)

    • Typically diffusely positive in monoblasts and promonocytes

Jun 13, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Acute Myeloid Leukemia with t(9;11)(p22;q23), MLLT3-MLL
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