| Session: Mast cell disease |
| Case number: 064 |
Submitter(s): Diane A. Hall, Cem Akin, Diane Roulston, Charles W. Ross.
Clinical history
A 65-year-old man presented for evaluation of mastocytosis. His symptoms included episodic diarrhea, nausea and vomiting, fatigue, weight loss and pruritis. Physical exam demonstrated hepatosplenomegaly. CT imaging revealed multifocal lymphadenopathy. Skeletal survey showed diffuse osteosclerosis. Family history was remarkable for plasma cell myeloma in his mother. His medications included loratadine (Claritin), ranitidine (Zantac), and calcium carbonate with vitamin D (Os-cal) .
CBC results: WBC 14,500/mm3, Hgb 14.5 g/dL, Hct 42.6%, platelet count 484,000/mm3 with 80% neutrophils, 14% lymphocytes, 4% monocytes, 0.5% eosinophils and 1.5% basophils. Serum protein electrophoresis revealed an IgG lambda monoclonal gammopathy, 1.9 g/dL. 24 hour urine showed trace lambda Bence Jones protein and intact monoclonal IgG lambda. Serum tryptase was elevated at 685 ng/mL.
After receiving the diagnosis of systemic mastocytosis with concomitant plasma cell myeloma, the patient showed dramatic clinical improvement on oral glucocorticoids, but was lost to follow-up.
Details of gross/microscopic pathology:
Axillary lymph node (formalin fixed) and bone marrow (B5 fixed) biopsies showed multifocal infiltrates of atypical CD117 and tryptase-positive mast cells. The bone marrow additionally demonstrated an IgG lambda-restricted interstitial plasmacytosis with prominent Russell and Dutcher bodies. The peripheral blood smear was unremarkable.
Immunophenotype (flow cytometry/immunohistochemistry):
Immunophenotypic analysis of the CD117 positive mast cells by flow cytometry showed aberrant coexpression of CD25.
Cytogenetics:
Normal male karyotype with a nonclonal abnormality, 46,XY[19]/46,XY,t(5;17)(p12;q25)[1]. There was no evidence for loss or deletion of chromosome 13 by FISH analysis of 300 interphase cells.
Molecular analysis:
The bone marrow aspirate demonstrated the D816V point mutation in the c-kit gene.
Interesting feature(s) of submitted case:
Systemic mastocytosis has been associated with clonal hematologic non-mast cell lineage diseases. Myeloproliferative and myelodysplastic neoplasms constitute the majority of these cases. Association of systemic mastocytosis with a plasma cell dyscrasia, as in the case presented here, is rare.
Proposed diagnosis:
Systemic mastocytosis with concomitant plasma cell myeloma.
Panel diagnosis:
agree with proposed diagnosis
Comments:
Studies performed by the panel: positive for D816V mutation, CD25+
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