AML with inv(3)(q21q26.2) or t(3;3)(q21;q26.2)

Epidemiology and Etiology:

· de novo or from prior MDS

· adults mostly

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Common sites:

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Gross features:

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Histologic features:

• increased atypical BM megakaryocytes
• mono- or bi-lobed nuclei
• multilineage dysplasia
• hypogranular neutropils with a pseudo-Pelger-Huet anomaly maybe
• giant and hypogranular platelets common
• bare megakaryocyte nuclei maybe
• blasts with morphologic and cytochemical features of any FAB subtype other than APL
• without maturation, myelomonocytic, or megakaryoblastic most common
• increased small hypolobated megas
• erythroid and neutrophil dysplasia common
• CML may acquire these 3q abnormalities
• Usually portends accelerated or blast phase of the disease

· Best considered aggressive phase of CML rather than AML with 3q abnormality

Immunophenotype:

Marker:

Sensitivity:

Specificity:

• generally: CD13, CD33, HLA-DR, CD34, CD38
• maybe: CD7, CD41, CD61
• uncommon: lymphoid markers other than CD7

Molecular features:

· EVI1 at 3q26.2

· RPN1 at 3q21

· RPN1 may act as an enhancer of EVI1 expression resulting in increased cell proliferation and impaired cell differentiation

· Secondary karyotypic abnormalities (may precede the 3q abnormality):

· Monosomy 7 most common (~50%)

· 5q deletions

· Complex karyotypes

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Other features:

· normal or elevated PB platelet counts

· prognosis:

· unfavorable

· short survival

· case reports have responded to arsenic trioxide with thalidomide

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References:

· Swerdlow. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissue. 4th ed. WHO Publications; 2008.

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