| Session: Myelodysplastic / myeloproliferative disease |
| Case number: 195 |
Submitter(s): Dita Gratzinger, Tracy George.
Clinical history
The patient is a 64 year old woman with a previous history of myelodysplasia diagnosed in 2000. The patient was treated with erythropoietin until 2005, when G-CSF was added to the regimen. In 2006 the patient became transfusion-dependent, and a bone marrow evaluation was performed in preparation for a non-myeloablative bone marrow transplant.
CBC: WBC 13.8 K, RBC: 2.32M/uL, Hg 7.6 g/dL, Hct 22%, MCV 94.6 fL, Plt 466 K/uL, RDW 29%, Neuts 76%, Lymphs 13%, Monos 10% (1.5K/uL), Eos 1%, Basos 0.2%.
Details of gross/microscopic pathology:
The peripheral blood smear shows dimorphic red cells with oval macrocytes and occasional teardrops. There is neutrophilia with some hypogranular neutrophils, absolute monocytosis with many immature monocytes, but no circulating blasts. Platelets are increased in number with many large and occasional hypogranular forms.
The bone marrow aspirate shows left-shifted, mildly megaloblastic erythroid and myeloid maturation and increased megakaryocytes including numerous small hypolobated forms as well as large hyperlobulated forms. An iron stain shows increased storage iron and frequent ringed sideroblasts.
The bone marrow biopsy shows hypercellularity (90%) with left-shifted myeloid and erythroid maturation and clustered atypical megakaryocytes. There is no increase in blasts morphologically. Reticulin fibrosis is mildly increased (1 to 2+).
Immunophenotype (flow cytometry/immunohistochemistry):
There is no increase in blasts on CD34 immunostaining.
Flow cytometry on a prior specimen showed partial aberrant expression of CD56 both on myeloid blasts and on monocytes.
Cytogenetics:
Conventional cytogenetics shows a normal 46X,X karyotype.
Molecular analysis:
JAK-2 mutational analysis is pending.
Interesting feature(s) of submitted case:
The patient has refractory anemia with thrombocytosis, absolute monocytosis, and dysplastic neutrophils. The bone marrow shows prominent megakaryocytic dysplasia with ringed sideroblasts on iron stain. The combination of refractory anemia with ringed sideroblasts and thrombocytosis places this process in the WHO category of unclassified mixed myelodysplastic/myeloproliferative processes, with features of the provisional entity of refractory anemia with ringed sideroblasts and thrombocytosis (RARS-T). The presence of absolute monocytosis also raises the possibility of chronic myelomonocytic leukemia. The category of RARS-T has recently been shown to be biologically distinct, with a high proportion of cases positive for the JAK2 V617F mutation in one study (Szpurka H et al, Blood 2006 108(7);2173-81).
Proposed diagnosis:
Refractory anemia with ringed sideroblasts and thrombocytosis (RARS-T).
Panel diagnosis:
This case cannot be classified due to lack of the original material.
Comments:
Additional information from the submitter: JAK2 mutational studies were negative. The patient's biopsy in 2000 was unfortunately performed at an outside institution and is not available for evaluation. However the patient has since undergone a non-myeoloablative allogeneic BMT and a bone marrow biopsy performed 3 months post transplant shows persistent myelodysplasia and ringed sideroblasts.
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