| Session: Mast cell disease |
| Case number: 021 |
Submitter(s): Dana T. Kausmeyer, Michael G. Bayerl, J. Ander Pindzola, Ashraf A. Abou-Elella.
Clinical history
61 y.o. man with 5 months of early satiety, 29.5 kg weight loss, night sweats, splenomegaly and pancytopenia.
PMHX: Psoriasis and rheumatoid arthritis.
Meds: Methotrexate, infliximab
CBC after RBC transfusions: WBC 3.7 x 109/L, Hb 10.7 g/dL, HCT 33.6%, RBC 3.58 x 1012/L, MCH, MCHC 31.8 g/dL, MCH 29.9 pg, MCV 93.9 fL, RDW 16.0%, PLT 122 x 109/L.
WBC Diff: 0% myeloblasts, <1% promyelocytes, 2% neutrophilic myelocytes, 3% neutrophilic metamyelocytes, 66% segmented and band neutrophils, 11% eosinophils, <1% basophils, 8% monocytes. No circulating mast cells.
Follow-up: Following splenectomy, WBC increased to a peak of 90 x 109/L, then fell to a steady-state around 50 x 109/L. Transfusion requirement dereased.
Therapy with imatinib mesylate was initiate with no clinical or hematological response. He died 2 months later of massive hemorrhage.
Details of gross/microscopic pathology:
Blood: WBC: Eosinophilic leukocytosis, some hypogranular neutrophils. RBC: normocytic and normochromic. PLTS: Normal.
Bone Marrow: Aspirate: Dry tap. Imprints were hypocellular with a few spindled and hypogranular mast cells admixed with a few granulocytic and erythoid lineage cells. No increase in blasts or dyspoiesis outside of mast cells. Biopsy: 100% cellular with classic perivascular, partrabecular and targetoid mast cell infiltrate with associated fibrosis. The remaining marrow is hypercellular with panmyelosis, myeloid intermediate excess, mild to moderate interstitial reticulin fibrosis, but no overt increase in blasts.[figure1][figure2]CD117[figure3]
Spleen: 3550 g., homogeneus dark red. Red pulp expanded by EMH with focal mast cell aggregates in both red and white pulp. Mast cells CD117+ and tryptase+.[figure4][figure5][figure6]CD117[figure7]Tryptase[figure8]
Immunophenotype (flow cytometry/immunohistochemistry):
Flow cytometry (marrow): 0.09% CD34-positive, 0.63% CD117-positive.
Flow cytometry (blood): No circulating mast cells or myeloblasts.
Immunoperoxidase (marrow and spleen): CD117 and tryptase positive in mast cells, CD34 positive in <1% of cells.
Cytogenetics:
Bone marrow: 44, XY normal male. No BCR/ABL or trisomy 8 detected by FISH.
Molecular analysis:
Bone marrow: No BCR/ABL by RT-PCR.
Interesting feature(s) of submitted case:
1) Systemic mastocytosis with associated clonal, hematological non-mast cell lineage disease.
2) Beautiful morphology of SM-AHNMD in bone marrow and spleen
3) No response to imatinib mesylate. No further molecular studies were available at the time this patient was diagnosed.
Proposed diagnosis:
Systemic mastocytosis with associated BCR/ABL-negative chronic myeloproliferative disease, unclassifiable.
Panel diagnosis:
agree with proposed diagnosis
Comments:
Studies performed by the panel: positive for D816V mutation
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