| Session: Mast cell disease |
| Case number: 230 |
Submitter(s): April Chiu, Elizabeth Hyjek, Susan Mathew, Ellen Ritchie, Gail Roboz, Scott Ely, Amy Chadburn.
Clinical history
A 67 y/o man with h/o osteoarthritis, gout and BPH presented with fever and night sweats. He received antibiotics for UTI but did not respond. Medications: allopurinol, flomax, avodart, prednisone. CBC: WBC-4 (lymph-19; mono-20; eos-7; baso-1; neutrophil-39; band-4; meta-5; myelocyte-3; pro-1, blast-1); Hb-12.7; PLT-158. Other lab results: ALT-46; alkaline phosphatase-484; osteopenia on bone scan. A BM bx was performed (2005). The pt received 2 cycles of arsenic/ara-C with good response, and underwent allo- BMT. Four months later he re-presented with fever. CBC: WBC-13.2 (lymph-19; mono-25; eos-1; baso-0; neutrophil-39; band-4; meta-2; myelocyte-4; pro-1; blast-5); Hb-12; PLT-147. A BM bx was performed (2006). The pt received cytarabine+daunorubicin (7+3) chemotherapy but never achieved remission.
Details of gross/microscopic pathology:
BM bx 2005 (Bouin's) shows prominent paratrabecular fibrosis. The bone is slightly osteosclerotic. Within the fibrotic foci many cells with oval to spindled nuclei and moderate cytoplasm surrounded by small lymphocytes are seen. Markedly reduced numbers of maturing myeloid and erythroid cells and a few megakaryocytes with hypolobated nuclei are seen. The BM aspirate shows 3% blasts and megakaryocytic and granulocytic dysplasia. Mast cells are seen but not in significantly increased numbers. BM bx 2006 (Bouin's) shows markedly increased cellularity. Myeloid maturation is left shifted with a large number of blasts. The erythroid cells and megakaryocytes are decreased in numbers. The BM aspirate shows 49% blasts (MPO+) and granulocytic and erythroid dysplasia. Mast cells are seen but again are not significantly increased in number. PB smear showed few blasts.
Immunophenotype (flow cytometry/immunohistochemistry):
IHC of 2005 specimen showed many mast cells expressing CD117 and mast cell tryptase within the paratrabecular aggregates. These are surrounded by CD3+ T cells and Pax-5+ B cells. Flow cytometric and IHC analyses showed no significant increase in blasts or evidence of malignant lymphoma. Flow cytometric analysis of 2006 specimen shows 34% CD34+ and 31% CD117+ blasts, which expressed CD7, CD13 and CD33. IHC of this bx showed 30-40% CD34+, CD117+ and MPO+ blasts. Mast cells are less numerous in this bx.
Cytogenetics:
Conventional cytogenetics of both specimens show monosomy 7 in 95% cells. FISH shows 21% donor and 79% host cells in the second specimen.
Molecular analysis:
Interesting feature(s) of submitted case:
Mast cell disease w/ MDS, transformed to AML.
Proposed diagnosis:
2005: Mast cell disease associated with MDS. 2006: AML (progression from MDS, s/p allogeneic transplant).
Panel diagnosis:
agree with proposed diagnosis
Comments:
Studies performed by the panel: WT c-kit, CD25+
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