| Session: Ph- chronic myeloproliferative disease |
| Case number: 100 |
Submitter(s): David Viswanatha.
Clinical history
This case concerns a 69 year old female diagnosed with polycythemia vera (P. vera) in 1986 and treated with phlebotomy. In May 2006, she presented with leukocytosis and progressive anemia and was diagnosed with post-polycythemic myelofibrosis in a bone marrow biopsy. She was clinically stable until October 2006, when she developed pain in the right upper back. CT and MRI scans revealed a T5-T7 paraspinous mass. She developed bruising and low grade fever, as well as a 5 pound weight loss in the month preceding the current presentation. Her presenting CBC was as follows: Hgb 14.5 g/dL, MCV 71.8 fL, WBC 27.5 X 109/L, platelets 145 X 109/L.
Details of gross/microscopic pathology:
Peripheral blood smear demonstrated leukoerythroblastic features and 5% agranular blasts with rare Auer rods. The marrow aspirate was hemodilute. The biopsy touch imprint preparation revealed 10% blasts with a subset containing single Auer rods. No myelodysplastic features were noted. The B5-fixed marrow biopsy demonstrated 100% cellularity with panhyperplasia and atypical megakaryocytes. Increased interstitial blasts were present. Subsequently, a formalin-fixed, paraffin-embedded tissue biopsy from the T7 paraspinal mass was diagnosed as a myeloid sarcoma.
Immunophenotype (flow cytometry/immunohistochemistry):
CD34 and CD117 immunoperoxidase markers performed on sections of the bone marrow core biopsy confirmed an increase in myeloblasts (< 20% overall) with focal areas of increased density.
Cytogenetics:
Classical karyotype studies of the marrow aspirate revealed a t(8;21)(q22;q22) in 4 of 20 metaphases. These results were confirmed by fluorescence in situ hybridization (D-FISH) analysis of the same sample with probes directed to the ETO and AML1 (CBFA) gene loci, showing 11.8% fusion signals for AML1-ETO.
Molecular analysis:
Quantitative allele-specific PCR analysis for the JAK2 V617F gene mutation was positive.
Interesting feature(s) of submitted case:
This case demonstrates a history of progression of P. vera to a myelofibrotic stage, followed by a subacute transition to an apparent accelerated phase with increased bone marrow blasts (10%) containing Auer rods. This pathologic scenario raises the possibility of transformation to acute myeloid leukemia, but is not specifically delineated in the current W.H.O. classification of non-CML myeloproliferative disorders. The finding of the cytogenetic t(8;21)/AML1-ETO abnormality resulted in the more accurate classification of a low blast count AML transformation in this patient. The additional presence of a paraspinous granulocytic sarcoma is commonly observed in t(8;21) AML.
Proposed diagnosis:
Acute myeloid leukemia with the t(8;21) arising in a patient with post-polycythemic myelofibrosis and a concurrent extramedullary myeloid sarcoma.
Panel diagnosis:
agree with proposed diagnosis
Comments:
Panel comment: Review of original biopsy recommended. Additional information from the submitter: This patient came to us less than a year ago for evaluation and Rx of her disease transformation. Original biopsies were not available for review. Clinician notes refer to her long-standing Hx of P. vera, with at some point, development of fibrosis and myeloid metaplasia. CBC from November 1986: Hgb 22 g/dL, Hct 64%, WBC 7.7, platelets 447 X 10e9/L. No records of red cell mass. Patient treated with phlebotomy.
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