[1371] Increased Bone Marrow Mast Cells, Enumerated by Multiparameter Flow Cytometry, Are Associated with Myelodysplastic Syndromes

Fernando J Castro-Silva, Franklin S Fuda, Nitin J Karandikar. University of Texas Southwestern, Dallas, TX

Background: Mast cells (MC) are involved in certain tissue inflammatory responses and largely differentiate in extramedullary sites. Flow cytometric (FC) enumeration and characterization of mast cells in bone marrow (BM) specimens has been studied predominantly in MC disease. As a result of prevalent FC gating strategies, mast cells are not enumerated in routine practice and the value of doing so is unclear. We examined the relationship between detectable populations of MC and their potential association with non-MC lineage neoplastic disorders in BM specimens.
Design: We evaluated consecutive BM specimens from our institution during a recent 4-month period and selected cases that had undergone thorough morphologic, cytogenetic and FC evaluation (a panel of >25 lymphoid and myeloid antigens with cluster analysis of ungated data). Using a combination of antibodies against CD2, CD117, CD45 and CD34, MCs were enumerated based on their staining pattern and light scatter properties. Hematopathologic diagnosis of each specimen was obtained from medical records.
Results: In the 121 cases identified, MC percentage ranged from 0.0 to 0.29%, [mean 0.03% and median 0.01%]. Only 20 (17%) cases showed a distinct cluster of MC at ≥ 0.05%. Of these, 5 (25%) were associated with a myelodysplastic syndrome (MDS), 2 with acute myeloid leukemia (AML) and 13 with negative/reactive findings. In contrast, 101 cases (83%) had low to undetectable MC (< 0.05%). Within this group, only 2 cases (2%) had MDS, 21 AML, 5 chronic myeloproliferative neoplasms, 4 lymphoblastic leukemia/lymphoma, 4 mature B-cell neoplasms, 1 mixed lineage leukemia and 64 negative/reactive findings. None of these cases had MC disease. Overall, there was no significant difference between the distribution of neoplastic vs. negative/reactive cases in the two cohorts [7/20 (35%) vs. 37/101 (37%); p=1.0]. However, there was significant association between high MC percentage and MDS [5/20(25%) vs. 2/101 (2%), p=0.001].
Conclusions: There is a highly significant correlation between increased MC and MDS. These findings suggest that enumeration of MC in BM can support the diagnosis of MDS comparable to other FC findings such as abnormal light scatter and aberrancies of CD56 and CD10 on granulocytes. Thus, routine analysis strategies should incorporate the quantitation of MC. Interestingly, a subset of systemic mast cell disease is known to be associated with MDS, raising the possibility of a biologic connection between the MDS and associated mast cell proliferation.
Category: Hematopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 237, Tuesday Morning


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