[1425] Acute Myeloid Leukemia Associated with Isolated Del(6q) Demonstrates Unique Clinical, Morphological and Cytogenetic Characteristics

Daniela Hoehn, Pei Lin, Ramya Muddasani, David Ng, Ken H Young, Gary Lu. The University of Texas M.D. Anderson Cancer Center, Houston, TX

Background: Deletion in the long arm of chromosome 6, del(6q), is a recurrent cytogenetic abnormality known to be common in lymphoid neoplasms including B-acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia, myeloma and non-Hodgkin lymphomas. Here, we indentified isolated del(6q) as the sole genetic abnormality occurring in 4 de novo acute myeloid leukemia (AML) cases with unique Clinical, Morphological and Cytogenetic features.
Design: We retrospectively reviewed the database to collect AML cases associated with isolated del(6q), detected by conventional cytogenetics performed on bone marrow aspirates. Peripheral blood, bone marrow core biopsy, clot sections (H&E), and aspirate smears (Wright Giemsa) were used as resources for the analysis. Multicolor flow cytometric immunophenotypic findings, molecular results and clinical data were analyzed.
Results: We identified 4 de novo AML cases, with isolated del(6q), as the sole genetic abnormality. There were 2 males and 2 females with an age range of 68 to 76 years (median 72.7). The blast count ranged from 32% to 77% (median 40%); trilineage dysplasia was present in 1 of the 4 AML cases. Using the 2008 WHO classification, three cases were classified as AML not otherwise specified and 1 case was AML with myelodysplasia-related changes. Using the FAB classification, the 4 AML cases were classified as M0, M4, M5b and CMML-2. RAS mutation was identified in 2 AML cases. Immunophenotyping confirmed the myeloid lineage of the blasts in all 4 AML cases with no distinct aberrant immunophenotype. Peripheral blood data showed WBC count ranging from 0.4∼120.4 (K/UL) (median 6.5), platelet count 32∼330 (K/UL) (median 50.5) and hemoglobin 6.3∼11.6 (g/dl) (median 9.35). The median overall survival was 6.7 months (range 5∼62). The small region deletion was identified in the long arm of chromosome 6 in all 4 AML cases on the 6q23 locus.
Conclusions: Isolated del(6q) occurs in a small subset of AML cases and is associated with a short overall survival and similar immunophenotypes to other AML types. This suggests the 6q23 region most likely harbors candidate tumor suppressor gene(s) that may implicate tumorigenesis at an early stage of stem cell differentiation.
Category: Hematopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 210, Tuesday Morning


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