| Session: Ph- chronic myeloproliferative disease |
| Case number: 067 |
Submitter(s): Tove V. Isaacson, William G. Finn.
Clinical history
A 78-year-old woman was found on routine exam to have eosinophilia with bilateral axillary and inguinal lymphadenopathy but no hepatosplenomegaly. At the time of bone marrow aspirate and biopsy, the patient's white blood count was 77,000/uL with an absolute eosinophil count of 40,500/uL.
Details of gross/microscopic pathology:
A differential count of the peripheral blood smear revealed 56% eosinophils with atypia including small clusters of large granules with cytoplasmic clearing and/or nuclear hypersegmentation, a shift to immaturity in the neutrophils (26% segmented neutrophils and bands, 4% metamyelocytes, 3% myelocytes) with occasional neutrophils showing hypolobation and hypogranulation, 1% basophils, 3% monocytes, and 7% lymphocytes.
The bone marow core biopsy was hypercellular (90% cellularity) and showed myeloid expansion of both neutrophils and eosinophils. Megakaryocytes appeared adequate to slightly decreased in number.
A differential count of an aspirate smear revealed 0.6% blasts, 2.8% promyelocytes, 35.0% neutrophils and granulocytic precursors, 8.4% erythroid precursors, 4.8% lymphocytes, 44.8% eosinophils, 1.0% basophils, and 2.6% monocytes. The myeloid to erythroid ratio was 10:1.
Immunophenotype (flow cytometry/immunohistochemistry):
Flow cytometric analysis of a bone marrow aspirate revealed no definitive immunophenotypic evidence of a lymphoid neoplasm or aberrant blast elevation.
Cytogenetics:
Cytogenetic analysis revealed a normal female karyotype (46,XX[20]).
A FISH study for CHIC2 anomalies with probes for 4q12 (CHIC2,FIPL1, PDGFRA) and 4p16.3 (FGFR3) indicated that of 200 nuclei, 85% had a single signal for CHIC2, and two signals for FGFR3. Deletion of CHIC2 has been shown to be a surrogate marker for FIP1L1/PDGFRa fusion that characterizes a subset of chronic eosinophilic leukemia.
Molecular analysis:
BCR/ABL quantitative analysis of a peripheral blood specimen was negative for BCRABL fusion transcripts.
Interesting feature(s) of submitted case:
Patients with chronic eosinophilic leukemia associated with the FIP1L1-PDGFRA fusion gene produce a tyrosine kinase which has been shown to be strongly inhibited by imatinib mesylate therapy, and such patients may respond dramatically to relatively low imatinib doses. The current patient was treated with a regimen of only 100mg of imatinib per day, and her peripheral blood cell counts normalized, including a reduction of her peripheral absolute eosinophil count to zero.
Proposed diagnosis:
Chronic Eosinophilic Leukemia associated with FIP1L1/PDGFRa fusion, and highly responsive to low dose imatinib.
Panel diagnosis:
agree with proposed diagnosis
Comments:
PowerPoint:
Presentation Link
Images:
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