| Session: Ph- chronic myeloproliferative disease |
| Case number: 125 |
Submitter(s): Rebecca F. McClure.
Clinical history
60 year old male with no significant prior medical history and taking no medications.
Presented with a 6 month history of "feeling tired when I exercise". Normal physical exam.
CBC: Hb 10.3 g/dL; RBC 3.78 x 1012/L; MCV 81 fL; RDW 20%; WBC 7.3 x 109/L; Plt 614 x 109/L
Blood Differential: neutrophils 62%; lymphocytes 30%; monocytes 6%; eosinophils 2%
Bone Marrow Differential (55 cell unit prep): neutrophils (segs [sub]&[/sub] bands) 36%; metamyelocytes 10%; myelocytes 5%; promyelocytes 1%; eosinophils 9%; basophils 1%; normoblasts 28%; monocytes 2%; lymphocytes 5%; plasma cells 1%; blasts 2%.
Details of gross/microscopic pathology:
Blood: Normocytic anemia with moderate anisocytosis (occasional hypochromic microcytes, slight polychromasia) and no poikilocytosis. Normal absolute WBC counts and normal WBC cytology. Thrombocytosis with normal platelet morphology. Bone Marrow Aspirate (Wright-Geimsa): Cellular, with estimated M:E ratio of 2:1. Aside from a slight increase in eosinophils, erythroid precursors, neutrophil precursors and other granulocytes are all present in normal proportions and show normal cytology. Megakaryocytes appear normal. Monocytes, lymphocytes, plasma cells and blasts are all present in normal proportions and show normal cytology.
Stainable storage iron is normal with no ringed sideroblasts (iron stain on aspirate specimen).
Bone Marrow Biopsy (formic acid decalcification, formalin fixation, paraffin-embedding, H&E): Hypercellular for age (60-70%). The increase in cellularity is due to panmyeloid hyperplasia with erythroid precursors and eosinophils increased to a slightly greater extent than the other myeloid cell lines. Megakaryocyte morphology is not clearly atypical. There is no increase in lymphocytes, plasma cells or blasts.
Bone trabeculae are normal.
There is no increase in reticulin fibrosis (reticulin stain).
Immunophenotype (flow cytometry/immunohistochemistry):
No immunophenotyping was performed.
Cytogenetics:
Bone marrow karyotype: Normal, 46,XY in 20 of 20 metaphases.
Molecular analysis:
BCR/ABL(bone marrow)(FISH): Negative
JAK2 V617F (bone marrow)(quantitative allele-specific PCR): Positive, with a mutated to non-mutated allele ratio of 0.005 (0.5% mutated alleles).
Interesting feature(s) of submitted case:
This case highlights the diagnostic dilemma of a patient with clinical features suspicious for a non-CML chronic myeloproliferative disorder, non-diagnostic blood and bone marrow morphologic features but a postive JAK2 V617F assay with very low mutation burden.
The critical question is whether a positive, but very low level, JAK2 result is sufficient to fully support a diagnosis of a chronic myeloproliferative disorder in the absence of other diagnostic features.
Proposed diagnosis:
Descriptive until further follow-up:
Hypercellular bone marrow (60-70%) with panmyeloid hyperplasia and associated with normocytic anemia, thrombocytosis and a minimal JAK2 V617F mutation burden. The features are insufficient to support a diagnosis of a chronic myeloproliferative disorder at this time.
Panel diagnosis:
agree with proposed diagnosis
Comments:
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