i(17)(q10)

Epidemiology and Etiology:

· By far the most frequent neoplasia-associated isochromosome overall

· CML

· AML

· M>F (2.3:1)

· Elderly (almost exclusively), median 65 y.

· Almost always de novo rather than after chemotherapy

· MDS

· MPN

· Lymphoid disorders

· Formed by an intrachromosomal recombination event

Common sites:

·

Gross features:

· AML:

· Splenomegaly maybe

· Hepatomegaly maybe

Histologic features:

· AML:

· All FAB subtypes except M6

· Prominent basophilia and eosinophilia

· Dysplastic megakaryocytes

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

· Actually it is a dicentric chromosome

· Clustered breakpoints in 17p11

· TP53 gene deleted

· But accompanying TP53 mutations have not been particularly associated

· ?TP53 is not the target of this lesion

· AML:

· Sole change in 40%

· Common additional abnormalities:

· +8, -7, -5, +13, +11, +19, -12

· Rarely a secondary change to characteristic AML-associated translocations and inversions

· CML:

· Common secondary change to t(9;22)

· May appear to be the sole change in the presence of a cryptic t(9;22)

· MDS and MPN:

· Isolated usually

Other features:

· MDS and MPN:

· Associated with rapid progression to AML

· AML:

· Poor response to chemotherapy

· Short survival

References:

· Heim S, Mitelman F. Cancer Cytogenetics. 3rd ed. Wiley-Blackwell; 2009.