[1316] Comparative Analysis of Detecting Monocytic Cells and Their Aberrancy

CH Dunphy. University of North Carolina, Chapel Hill, NC

Background: The detection of monocytic cells(MCs) in bone marrow(BM) and MC aberrancy are important in the diagnoses of chronic myelomonocytic leukemia(CMML) and acute MML(AMML) and monocytic/blastic leukemia(AMoL). MCs may be identified by cytomorphology(CM), flow cytometric analysis (FCA)(i.e., detection of CD14, CD11b, CD15, CD13, CD33, and CD64, and aberrancy by detection of CD2 and/or CD56) and by immunohistochemical analysis(IHCA)(i.e., detection of CD14, CD33, CD68, CD163, and possibly CD123, and aberrancy by CD2 and/or CD56 reactivities). The purpose of this study is to compare the detection of MCs and MC aberrancy by these methods.
Design: Forty BM(aspirate, clot, and formalin-fixed, decalcified-5% acetic acid-biopsy) samples(7 CMMLs; 33 AMMLs and AMoLs) are evaluated by CM, FCA(35 BM and 5 peripheral bloods), and retrospective IHCA(CD14, CD33, CD68. CD163, and CD123 according to kit procedures). The detection of MCs and MC aberrancy(i.e., sensitivity-SENS and specificity-SPEC) are compared by these methods.
Results: A high percentage(45%) revealed a greater (>) percentage of BM MCs by FCA than by CM. Only 41% showed high concordance by FCA and CM. When comparing CD14 by FCA versus IHCA, the majority(53%) showed > SENS by FCA. CD2 and CD56 detections also showed > SENS by FCA(CD2 was detected in 3 by FCA and in 0 by IHCA; CD56, in 16 by FCA and in a subset-6/16 by IHCA). By IHCA, CD14 showed high SPEC for MCs. CD68 and CD33 showed low SPEC, marking histiocytes, MCs, and myeloid cells. CD163 showed less SPEC than CD14, marking histiocytes and MCs, but > SPEC than CD68 and CD33. CD123 stained blasts within a subset of the AMLs(8 AMMLs and 4 AMoLs) and stained no CMMLs. By IHCA, CD123 did not correlate with CD14 or CD163. By comparing IHC reactivities in BM clot versus core, CD56 showed the highest correlation(93%), followed by CD14(85%) and CD33(70%). CD68 showed significantly > reactivity in clots in 48% of cases; CD163 showed > reactivity in clots in 44% of cases; and CD123 showed > reactivity in clots in 35% of cases. The > reactivities in clots are likely due to decalcification.
Conclusions: The most sensitive method to detect MCs in BMs and their aberrancy is FCA. When a BM is not available for FCA, CD14 remains the most specific IHC marker for MCs. CD68 and CD33 are nonspecific and CD163 is less specific than CD14. CD123 is not sensitive for MCs, inconsistently marking AMMLs and AMoLs. Evaluation of other AML subtypes for CD123 expression should determine the usefulness of CD123 in AML subtyping, as well as for possible prognostic implications and targeted therapy.
Category: Hematopathology

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 178, Tuesday Afternoon

 

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