| Session: Ph- chronic myeloproliferative disease |
| Case number: 133 |
Submitter(s): J. A. Schrager, I. Maric.
Clinical history
54 yo man with pancytopenia, splenomegaly, lung infiltrates and poor ejection fraction. Bone marrow exam was performed.
WBC 2.7 x 10^3/uL, RBC 3 x 10^6/uL, Hb 8.0 g/dL, Hct 24%, MCV 79 fL, RDW 18, Plt 33 x 10^3/uL
Empiric imatinib therapy resulted in rapid improvement.
Details of gross/microscopic pathology:
PB:
Pancytopenic. NRBCs are present. Myeloid cells are dysplastic with left shift. Rare blasts are present with primary granules (Fig 1). Immature myeloid cells have large eosinophilic granules (Fig 2). There are rare hypersegmented polys. Monos are immature/dysplastic. Lymphs are unremarkable. PB diff: 15% segs, 5% bands, 4% metas, 4% myelos, 2% blasts, 6% monos, 18% lymphs, 46% eos, 0.4% baso; 10 nRBC/100 WBC
BM touch prep:
Abundant Charcot-Leyden crystals (Fig 3).
BM core:
B5-fixed with brief decal. 1 cm of hypercelluar marrow (95%) (Figs 4-6) composed of myeloid cells with maturation arrest and numerous eosinophils/precursors and Charcot-Leyden crystals. Definitive blasts are not identified. Megas and RBC precursors are rare. Reticulin staining is increased (Fig 7). IHC studies: HLA-DR is positive in 30% of the myeloid cells in a patchy distribution (Fig 8). Stains for CD34 (Fig 9), CD117, MPO, CD4, lysozyme, CD1a, and S100 are negative.
Immunophenotype (flow cytometry/immunohistochemistry):
Flow Cytometry of PB:
CD45 vs side scatter: 56% grans, 28% monos, 11% lymphs, and 1% immature hematopoietic precursors. The grans express dim CD33, dim CD14 and show a spectrum of CD13 from dim to bright and a spectrum of HLA-DR expression from neg to bright; they are neg for CD34 and CD117. The monos express dim CD33 and show a spectrum of CD13 from neg to mod and a spectrum of HLA-DR expression from dim to bright; they are neg for CD34, CD117, and mostly neg for CD14 (Fig 10). The immature precursors express CD13 and CD33 and 70% of them are HLA-DR(+). Approximately 30% of them are also positive for CD34, CD117, and dim CD4. They are negative for other lymphoid markers. There is no evidence of acute leukemia.
Of the lymphs, 55% are T-cells with no antigen loss, 26% are polyclonal B-cells, and 18% are NK-cells.
Cytogenetics:
ND.
Molecular analysis:
FISH studies on PB:
Trisomy 8 in 4% of cells.
Probes for monsomy 5, 7, and 20, t(8;21), 11q23, inv16 (CBFB), and bcr/abl were negative.
Tests for FIP1L1/PDGFR alpha fusion are pending.
Interesting feature(s) of submitted case:
The pancytopenia and dry tap make this a challenging case. There are features of both MDS and MPD. Features favoring MDS include pancytopenia, hypercellular marrow, and dysplastic cells in PB. Splenomegaly, however, would favor MPD. The markedly hypercellular bone marrow with numerous eosinophils and Charcot-Leyden crystals is quite impressive. Many of the eosinophils are immature and some are dysplastic. He was empirically treated with imatinib which resulted in rapid clinical improvement.
Proposed diagnosis:
Chronic eosinophilic leukemia vs. MDS/MPD, unclassifiable with eosinophilia.
Panel diagnosis:
Preferred diagnosis: Chronic eosinophilic leukemia
Comments:
Additional information from the submitter: There was no evidence of the FIP1L1/PDGFRa fusion (on peripheral blood sample due to dry tap); however, the patient was pancytopenic.
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