| Session: Mast cell disease |
| Case number: 223 |
Submitter(s): Samer Z. Al-Quran, David D. Grier, Raul C. Braylan, Ying Li.
Clinical history
A sixty-year-old man presented with anemia and thrombocytopenia. Bone marrow biopsy at an outside hospital showed hypercellular marrow with extensive paratrabecular fibrosis, which was interpreted as a being consistent with a myeloproliferative/myelodysplastic syndrome. CT scan of the abdomen showed splenomegaly and a 2-cm nodular hypodensity in the anterior superior part of the spleen. The patient reported a pruritic rash of several weeks duration, which was treated with Benadryl and improved, and night sweats for several months. Clinical examination was unremarkable except for an erythematous maculopapular eruption in the inguinal region and the back. CBC showed hematocrit of 24.6, hemoglobin of 7.6, WBC of 7.6 and a platelet count of 52.0. Bone marrow biopsy was repeated in our institution.
Details of gross/microscopic pathology:
Bone marrow aspirate smears revealed trilineage hematopoiesis and increased numbers of atypical mast cells, some of which were hypogranulated.[figure1]The Bone marrow core biopsy and clot sections were markedly hypercellular[figure2]with focal extensive replacement by atypical round to spindle cells with abundant grayish cytoplasm and bland nuclei.[figure3]The uninvolved area of the marrow showed multilineage hematopoiesis with a cellular composition similar to that seen in bone marrow aspirate smears.
Immunophenotype (flow cytometry/immunohistochemistry):
An abnormal population of mast cells was detected by flow cytometry and was characterized by the bright expression CD117 with co-expression of CD25, CD2, CD45, CD33, partial expression of CD38 and HLA-DR and no expression of CD34, CD14, CD15, CD16 or other T- and B-cell related antigens.[figure4] The abnormal mast cells were positive for tryptase[figure5]and CD117 by immunohistochemistry.
Cytogenetics:
Normal male karyotype.
Molecular analysis:
Interesting feature(s) of submitted case:
This case demonstrates the role of flow cytometry in the detection and diagnosis of mast cell disease.
Proposed diagnosis:
Extensive bone marrow involvement by mast cell neoplasm (systemic mastocytosis in proper clinical setting).
Panel diagnosis:
Systemic mastocytosis
Comments:
Panel comment: SM-AHNMD cannot be excluded. Studies performed by the panel: positive for D816V mutation, CD25+
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