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october 7-9, 2012 • NEW ORLEANS, LA
systematically applied to the diagnostic work-up of solid
tumors. Here we propose a FC panel of markers for the
diagnostic screening and classification of pediatric cancer,
with emphasis on solid tumors. The proposed strategy
aims at differential diagnosis between tumoral and reactive
samples, hematological and non-hematological malignancies
and immunophenotypic classification of solid tumors. For
this purpose, 52 samples from 40 patients suspicious
of containing tumor cells were analyzed by FC versus
conventional histopathology+immunohistochemistry. The
overall concordance rate between FC and conventional
diagnostic approaches was of 96% (n=50/52), with 100%
agreement for both all reactive/inflammatory and non-
infiltrated samples and solid tumors, with only two false
negative cases. Additionally, clear discrimination among
samples infiltrated by hematopoietic vs. non-hematopoietic
tumor cells was systematically achieved. A relatively
limited panel of markers is proposed which may contribute
to differential diagnosis: neuroblastoma(CD56hi/GD2+/
CD81hi), PNET (CD271hi/CD99+), Wilms tumors(different
cell populations), rhabdomyosarcoma(NuMYOD1+/
NuMyogenin+), carcinomas(CD45-/EpCAM+), GCT(CD56+/
CD45-/NG2+/CD10+) and hemangiopericytoma(CD45-/
CD34+). In summary, our results show that FC is a fast
and useful complementary diagnostic tool to routine
histopathology, for the diagnostic screening and classification
of pediatric cancer.
P17
EXPRESSION OF CD25 CORRELATES WITH
PHILADELPHIA (BCR-ABL) CHROMOSOMAL
TRANSLOCATION IN PEDIATRIC B-ACUTE
LYMPHOBLASTIC LEUKEMIA.
Amos Gaikwad
1, 2
, Tarek Elghetany
2
, Christopher Threeton
1,
2
, Michael Cubbage
1, 2
, Tatiana Goltsova
1, 2
, Andrea M
Sheehan
2
, Jyotinder Punia
2
, Timothy Moore
1
, Xinyan Lu
1, 2
,
Choladda Curry
1
1
Texas Children’s Cancer and Hematology Center, Texas
Children’s Hospital,
2
Departments of Pediatrics and
Pathology, Baylor College of Medicine
Background:
Nearly 75-80% of pediatric B-acute
lymphoblastic leukemia (B-ALL) patients undergo complete
remission and long-term survival with current chemotherapy.
However, approximately 20% of patients ultimately have
a poor prognosis. Philadelphia chromosome-associated
translocation (Ph+) BCR-ABL t (9;22), which occurs
in about 3-5% of pediatric B-ALL, confers the worst
outcome. Identifying Ph+ B-ALL is therefore crucial for risk
stratification. CD25 (IL2a-receptor) expression was reported
to have association with Ph+ B-ALL in adult population.
However, no similar study has been performed in pediatric
B-ALL.
Methods and Results:
Retrospective analysis of
consecutive patients with a new diagnosis of B-ALL (blood
and/or bone marrow) over three year period (2009-2012)
for CD25 expression and the presence of Ph+ translocation
by cytogenetic studies was performed. Specimens were
prepared according to standard procedures and analyzed
using BD FACSCanto flow cytometer. A threshold of 20%
was used to identify positive cases for CD25 expression.
Of the 233 patients, 127 were males and 106 were females
ranging in age from 3 months to 22 years (median, 5 years).
The median blast count was 76%. Eight cases of Ph+
B-ALL (3%) were identified; six of these expressed CD25.
In addition, eight Ph-negative-B-ALL expressed CD25.
Therefore, CD25 expression in predicting Ph+ B-ALL had a
75% sensitivity, a 96% specificity, whereas 43% and 99%
of positive predictive value (PPV), and negative predictive
value (NPV), respectively.
Conclusions:
CD25 expression is
a specific and relatively sensitive marker for the identification
of Ph+ B-ALL in the pediatric population. However, its NPV
far exceeds its PPV.
POSTER ABSTRACTS