[1354] CD56 Expression in Acute Lymphoblastic Leukemia of Childhood.

Margaret Ryan, Amy McGranahan, Xiayuan Liang. The Children's Hospital, Aurora, CO; University of Colorado Denver School of Medicine, Aurora

Background: CD56 antigen, a membrane glycoprotein, is a member of the immunoglobulin super-family. It is a crucial marker of natural killer (NK) cells and also expresses on a subset of mature T-cells and a subset cases of acute myeloid leukemia. The frequency and importance of this marker in association with acute lymphoblastic leukemia (ALL) in pediatric patients has not been closely studied and is greatly unknown. We examined CD56 expression in a large series of pediatric ALL cases in order to determine its significance in ALL, the most common neoplasm in childhood.
Design: 233 cases of newly diagnosed ALL (198 cases of B-ALL, 34 cases of T-ALL, and 1 case of true precursor NK cell leukemia) at The Children's Hospital, Colorado from 2003 to 2009 which had CD56 available were evaluated. Immunophenotype was performed by flow cytometry. Positive expression is defined as expression of a marker in ≥20% of blasts according to the criteria of the Children's Oncology Group.
Results: (1) CD56 expression was identified in 9 out of 233 cases (4%). Among these 9 cases, there were 5 cases of B-ALL (3%, 5/198), 3 cases of T-ALL (9%, 3/34), and 1 case of true precursor NK cell leukemia. (2) 3 cases of B-ALL with high CD56 expression (>50%) show co-expression of CD2. (3) 2 cases of T-ALL with high CD56 expression are double negative (CD4-CD8-) and both died within 1 year.

Table 1
DiagnosisCD34/TdT (%)CD2/CD7 (%)CD3/cCD3 (%)CD4/CD8 (%)CD19/CD20 (%)CD56 (%)Outcome
B-ALL97/9795/1NA/0NA/NA77/095CR x 6 ys
B-ALL99/4841/01/12/098/170CR x 1y
B-ALL99/3144/1NA/NANA/NA92/066Died in 1y
B-ALL93/302/3NA/2NA/NA91/2625CR x 5 ys
B-ALL80/780/1NA/NANA/NA87/022CR x 5 ys
T-ALL10/312/751/974/01/194Died in <1y
T-ALL100/495/10099/992/180/054Died in <1y
T-ALL92/14/962/9476/20/027CR x 4 ys
True precursor NK-cell leukemia0/096/263/52/30/096CR x 7 ys

Conclusions: (1) CD56+ ALL is rare (4%) and heterogeneous in lineage in ALL of childhood. (2) High expression of CD56 in B-ALL appears to associate with CD2 co-expression. (3) High expression of CD56 in T-ALL appears to associate with CD4-CD8- (double negative) stage and dismal outcome. These findings suggest that high expression of CD56 may affect the expression of some T-cell associated antigens in lymphoblasts and may also play an important role in outcome in T-ALL.
Category: Hematopathology

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 179, Wednesday Morning


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