| Session: Myelodysplastic syndrome |
| Case number: 165 |
Submitter(s): Sebastian J. Sasu.
Clinical history
The patient is an 82 year old male with a history of MDS treated with Dacogen, who presents with pancytopenia, worsening fatigue for 2-3 days, gum bleeding and melena.
Details of gross/microscopic pathology:
Bone marrow biopsy from the right iliac crest was obtained.
The peripheral smear showed normochromic, normocytic erythrocytes. The platelet count is markedly decreased. Rare giant platelets are seen. The white cells are markedly decreased. Occasional neutrophils display dysplastic features like hypogranulation and pseudo-Pelger-Huet nuclei. Rare blasts are noted.
A bone marrow differential (500 cells) revealed 5% myeloblasts, 23% myeloids and precursors, 60% erythroids and precursors (36% rubriblasts), 2% Lymphoid, 3% Eosinophils, 5% Basophils and 2% Plasma Cells.
Bone marrow aspirate smears show an M:E ratio of 0.9. There is an increase in the number of myeloblasts. The erythroids are left shifted and show dysplastic features such as prominent cytoplasmic vacuolation, binucleation, nuclear to cytoplasmic dyssynchrony and increased number of ringed sideroblasts on iron stains (>15%). The myeloids are left-shifted, hypogranular and hypolobated. Megakaryocytes are decreased in number and hypolobated.
The biopsy sections show a hypercellular marrow (~70%). Sheets of immature cells with open chromatin and prominent nucleoli are seen. The PAS stain highlights the immature erythroid cells.
Immunophenotype (flow cytometry/immunohistochemistry):
Numerous HemoglobinA positive erythroid cells and approximately 5% CD34 and CD117 positive blasts.
Flow cytometry: Blast gated population represents approximately 5% of total cells and is comprised of CD34 and CD117+ myeloblasts. The CD71 and Glycophorin A+ erythroid cells account for ~53% of the total cells. Myeloids show aberrant expression of CD56 and partial loss of CD11b.
Cytogenetics:
FISH analysis with 4 VYSIS probes specific for the 5q, 7q, 20q, and centromere 8 was performed. These studies showed a monosomy pattern for 5q in 88.0% (300/341) of cells.
KARYOTYPE: 46-48,X,-Y,+1,del(5)(q13q31),ider(11)(q10)dup?(11)(q13.1q14.1)x3,+add(12)(q15), -13/del(13)q12, add(14)(p12),+15,-18,-19/add(19)(p13.1).-21,+2-3mar[cp20].
The composite karyotype is highly abnormal and unstable, with anomalies including trisomies of 1 and 15, deletion of 5q, and 13q.
Molecular analysis:
Interesting feature(s) of submitted case:
Although strict criteria favor classification of this case as RAEB-2, the acute exacerbation, complex underlying karyotype and increased numbers of pronormoblasts raise the issue of transformation to acute myelogenous leukemia. This case illustrates the spectrum of disease of RAEB, RAEB in transformation and AML (erythroid, M6).
Proposed diagnosis:
Refractory anemia with excess blasts-2 (RAEB-2) (see comment)
Comment: The erythroid series is markedly increased (~60%) and is predominantly immature. Myeloblasts represent approximately 5-7% of total, thus less than 20% of non-erythroid cells.
Panel diagnosis:
RAEB-2 vs. AML-M6b
Comments:
Stains performed by the panel: glycophorin 80%, hemoglobin 80%, CD34 scanty, CD117 positive in mast cells, MPO negative in blasts, reticulin fibrosis 2+
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