| Session: Mast cell disease |
| Case number: 043 |
Submitter(s): Carl R. Kjeldsberg, Beatrice H. Muglia, Ronald L. Weiss, David W. Bahler, Sherrie L. Perkins.
Clinical history
This 42 year old woman presented with dyspnea and a skin rash.
Details of gross/microscopic pathology:
WBC 13.3, Hgb 9.3, Platelets 144K, Diff: 69% PMN, 7% lymphocytes, 22% atypical lymphocytes (mast cells), 2% myelocytes.[figure1][figure3][figure4]Bone marrow aspirate showed clusters of mast cells. Bone marrow biopsy showed a multifocal and diffuse involvement by mast cells.[figure5][figure6][figure8][figure7]The mast cells stained positively with tryptase and CD117.[figure9][figure10] Myeloperoxidase was negative.
Serum Tryptase > 200 mg/L< (0.4-10.9).
Immunophenotype (flow cytometry/immunohistochemistry):
Flow cytometry of bone marrow showed a 40% cell population with the following markers: CD2+, CD4+, CD8-, CD13+, CD33+, CD64+, CD117+, CD25+, CD34-, myeloperoxidase-.
The light scatter slide (ss=side scatter, FS=forward scatter) shows an atypical population of cells (arrows) that are larger than monocytes with FS similar to neutrophils but SS values slightly less than neutrophils. This population was gated and show the cells to express: CD117, CD33, and CD4 without CD14 similar to normal mast cells, but also express aberrant CD2 and CD25, which is typical for neoplastic mast cells but not normal mast cells. These histograms were made from bone marrow study, but the peripheral blood study gave the same results.[figure2]
Cytogenetics:
No abnormal clones were seen. FISH analysis showed no t(9;22).
Molecular analysis:
FISH for CHIC2 anomalies with probes for 4g12 (CHIC2, FIP1L1, PDGFRA) and 4p16.3 (FGFR3) was within normal limits.
Kit gene mutation studies revealed no mutations for KIT EXON 17. KIT EXON 11 failed.
Interesting feature(s) of submitted case:
This patient was seen by multiple physicians over a period of 2 months before a correct diagnosis was made. This is not unusual considering the complexity of mast cell disorders. It is difficult to diagnose both for the clinician and the pathologist for the following reasons:
1. It is a rare disease.
2. There is a wide diversity of clinical expressions.
3. The hematologic abnormalities are highly variable and there is a broad morphologic spectrum of the mast cells.
Proposed diagnosis:
Mast Cell Leukemia.
Panel diagnosis:
agree with proposed diagnosis
Comments:
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