| Session: Myelodysplastic / myeloproliferative disease |
| Case number: 072 |
Submitter(s): Michele R. Roullet, Ami D. Goradia, Gregory M. Lubiniecki, Adam Bagg.
Clinical history
A 75 year old African American female presented with fatigue. A CBC revealed the presence of marked anemia (Hgb 6.4 g/L), with a normal MCV (91fL), an elevated platelet count (669 x 109/L) and a normal WBC (7.0 x 109/L, with 32% segmented cells; 8% bands; 27% lymphocytes; 31% monocytes; and 2% eosinophils). The combination of anemia and thrombocytosis led to a presumptive clinical diagnosis of iron deficiency anemia (despite the normal MCV). However, there was no evidence of iron deficiency on serum iron studies. Accordingly, a bone marrow was performed.
Details of gross/microscopic pathology:
The bone marrow aspirate smear showed trilineage dysplasia (myeloid cells with hypolobation and hypogranulation; erythroid cells with nuclear budding and megaloblastoid change; and occasional monolobated megakaryocytes). Stainable iron was increased with numerous ringed sideroblasts (>50%) identified. The bone marrow biopsy was markedly hypercellular for age (80% cellularity) with a normal M:E ratio. Megakaryocytes were increased with frequent monolobated forms, and reticulin fibrosis was mildly diffusely increased.
Immunophenotype (flow cytometry/immunohistochemistry):
Not indicated.
Cytogenetics:
Bone marrow: 46, XX
Peripheral blood: FISH revealed del(5q31) in 2/400 cells.
Molecular analysis:
Negative for the JAK2 V617F mutation.
Interesting feature(s) of submitted case:
Although the ultimate diagnosis [of the 'unclassifiable' mixed myelodysplastic/ myeloproliferative disorder (MDS/MPD), refractory anemia with ringed sideroblasts (RARS) associated with marked thrombocytosis (RARS-T)] was clear cut, there were other putative differential diagnoses that might have been considered.
1. Given the associated monocytosis, one consideration might have been chronic myelomonocytic leukemia (CMML). Alternatively, given the questionable 5q- by FISH, a 5q- syndrome might also have been considered. Thus, the determination of which is the 'best fit' MDS/MPD or MDS diagnosis is an interesting feature warranting discussion.
2. At least one half of RARS-T cases harbor the JAK2 V617F mutation; what is the pathobiology of those cases, such as this one, which are negative for this mutation?
3. What is the 'best' methodology for detecting JAK2 V617F mutations?
4. What is the role of peripheral blood FISH in detecting MDS-associated abnormalities?
Proposed diagnosis:
Mixed myelodysplastic/myeloproliferative syndrome refractory anemia with ringed sideroblasts associated with marked thrombocytosis (RARS-T).
Panel diagnosis:
Chronic myelomonocytic leukemia
Comments:
Panel comment: No peripheral blood smear was available for review.
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