AML with t(9;11)(p22;q23)

Epidemiology and Etiology:

· Most common MLL translocation in AML

· children (9-12%) > adults (2%)

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Common sites:

· extramedullary myeloid (monocytic) sarcomas / tissue infiltration maybe

· gingival, skin

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Gross features:

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Histologic features:

· monocytic features (monoblasts, promonocytes)

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Immunophenotype:

Marker:

Sensitivity:

Specificity:

• children:
• strong: CD33, CD65, CD4, HLA-DR
• low: CD13, CD34, CD14
• NG2 homologue (most)
• Adults:
• Some markers of monocytic differentiation: CD14, CD4, CD11b, CD11c, CD64, CD36, lysozyme
• Variable immature markers: CD34, CD117, CD56

Molecular features:

· MLLT3-MLL

· MLL protein is a histone methyltransferase

· Assembles in protein complexes that regulate gene transcription via chromatin remodeling

· Secondary cytogenetic changes:

· +8 most common

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Other features:

· Intermediate survival

· Superior to other MLL translocations in AML

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References:

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