| Session: Myelodysplastic / myeloproliferative disease |
| Case number: 168 |
Submitter(s): Todd W. Kelley, Karl S. Theil.
Clinical history
The patient was a 61 year-old man with a 2 year history of progressive thrombocytosis (platelet count > 1,000,000/uL) and anemia. Treatment had been successful in controlling his platelets but frequent transfusions were required for anemia. Pertinent physical examination findings were splenomegaly without lymphadenopathy. His medications were anagrelide, thalidomide and prednisone. A CBC showed: WBC 6,700/uL, Hgb 8.6 g/dL, MCV 86.6 fL, Plts 329,000/uL. The peripheral blood differential cell count was significant for lymphopenia (670/uL).
Details of gross/microscopic pathology:
A peripheral blood smear showed poikilocytosis with teardrop red blood cells. The bone marrow aspirate revealed megaloblastoid erythroid precursors with occasional nuclear irregularities. Granulocytes exhibited predominantly normal maturation with rare Pelgeroid forms. Megakaryocytes were numerous and appeared enlarged with hyperlobulated nuclei. Blasts were not increased. An iron stain performed on the bone marrow aspirate smear showed numerous ringed sideroblasts. Storage iron was present. The bone marrow biopsy was hypercellular (>95% cellularity) due to panhyperplasia. Megakaryocytes were increased and clustered with hyperchromatic nuclei. A reticulin stain showed a diffuse increase in stromal reticulin (2+/4+).
Immunophenotype (flow cytometry/immunohistochemistry):
Immunohistochemistry and flow cytometry were non contributory.
Cytogenetics:
Cytogenetic analysis demonstrated a 46,XY[20] karyotype.
Molecular analysis:
Allele specific PCR and DNA melt curve analysis were performed on DNA extracted from formalin-fixed, paraffin-embedded bone marrow aspirate tissue. This demonstrated the presence of a JAK2 V617F mutation.
Interesting feature(s) of submitted case:
Cases with overlapping features of both a myelodysplastic syndrome and a myeloproliferative disorder (MDS/MPD) are diagnostically challenging. A more precise classification scheme based on objective molecular criteria would be helpful. Recently, the presence of the JAK2 V617F mutation has been identified in the majority of cases with the above features provisionally classified as refractory anemia with ringed sideroblasts and marked thrombocytosis (RARS-T). This may indicate that this entity is more appropriately classified as a myeloproliferative disorder.
Proposed diagnosis:
Refractory anemia with ringed sideroblasts and marked thrombocytosis (RARS-T).
Panel diagnosis:
MDS/MPD unclassifiable
Comments:
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