62
ICCS 2011
P26
Blasts With Megakaryocytic Differentiation
In Myelodysplasia By Flow Cytometry. Phenotypic
Comparison With Myeloid Proliferation In Down
Syndrome
Mariela Monreal
1
, Valeria Cismondi
1
, Olga Spinelli
1
,
Graciela Geraghty
1
, Marina Narvaitz
1
, Silvina Palmer
2
,
Alejandro Flores
3
, Luis Aversa
4
, Cristian Sanchez La
Rosa
5
, Isabel Giere
1
, Miguel A Pavlovsky
1
1
FUNDALEU, Buenos Aires, Argentina,
2
Hospital
Britanico de Buenos Aires, Buenos Aires, Argentina,
3
Sanatoria de la Trinidad Palermo, Buenos Aires,
Argentina,
4
Hospital de Niños Ricardo Gutiérrez,
Buenos Aires, Argentina,
5
Hospital Universitario
CEMIC Saavedra, Buenos Aires, Argentina
Immunophenotyping by fow cytometry (FC) has
a known diagnostic usefulness in myelodysplasia
(MDS) and related myeloid neoplasms. Since detailed
knowledge of normal maturation patterns is needed
for recognition of abnormalities, myelomonocytic
lineages have been the most extensively evaluated.
We report 3 adult patients (age 64-72; 2 males, 1
female) that met WHO diagnostic criteria for MDS: 2
refractary anemia with excess blasts (RAEB) and 1
refractary anemia (RA), with less than 10% blasts with
clear phenotypic evidence of megakaryocytic (MGK)
differentiation. Bone marrow specimens were tested
with 4-8 colour FC combinations; FACSCanto II and
Infnicyt software used for acquisition and analysis,
respectively. The expression patterns on blasts was
highly reproducible:CD45+ brCD36+ brCD38+ HLA
DR- CD71+ brCD7+ CD56- dCD4+ CD13+ CD33+
CD41+ CD117+/- CD34-/+. Phenotypic evidence of
dysplasia was detected on granulocytes and erythroid
populations as well. All patients presented with
thrombocytopenia (platelets <30x10
9
/L) and anemia
(hemoglobin 7 g/L) in 2/3. RAEB patients died within 7
months from FC evaluation (disease progression); RA
patient was initially transfusion dependent, currently
(8 months from FC) responding to treatment with
5-azacytidine. In addition, FC laboratory database
was searched for cases tested with the same panel
from January 2007 through March 2011, to assess
the prevalence of this atypical phenotype. Of a total
308 cases, 8 showed MGK phenotype. Interestingly,
while 5 of 8 cases were children classifed as myeloid
proliferation in Down Syndrome (MP-DS) with the
same distinct phenotype as our MDS group, the other
3 cases were adult megakaryocytic leukemia, with
differences in CD38, CD7, CD36, CD4 and CD56
expression. MP-DS is an entity with unique features,
frequently presenting as MDS with thrombocytopenia
and/or anemia. However, little information is available
addressing blasts with MGK commitment in MDS.
Our fndings contribute to recognition of informative
antibody combinations that should be considered in
the characterization of myeloid stem cell disorders.
POSTER ABSTRACTS