[1426] Diagnostic Utility of CD14, CD33, CD123, and MPO Immunostains in Myelomonocytic Neoplasms

MA Rollins-Raval, CF Garcia. University of Pittsburgh Medical Center, Pittsburgh, PA

Background: The diagnosis and subclassification of myelomonocytic neoplasms requires enumeration of blasts/promonocytes on aspirate smears.However, morphologic distinction between promonocytes and more mature monocytic cells may be subjective,and distinction between chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia with monocytic differentiation (Mo-AML) can be problematic.We used a panel of immunohistochemical (IHC) stains on bone marrow (BM) biopsies to evaluate its diagnostic utility for myelomonocytic neoplasms.
Design: IHC stains for CD14, CD123, CD33,& MPO were performed on BM biopsies on 18 CMML, 26 Mo-AML,5 non-monocytic AML with minimal maturation (NM-AML), & 10 non-neoplastic cases (3 reactive monocytosis,7 negative staging BM). Monocytic differentiation in AML was confirmed by NSE in 28 cases. Cases were reviewed & morphologic features were correlated with the flow cytometric (FCM) data,clinical & cytogenetic features. Per 2008 WHO criteria, Mo-AMLs could be subclassified as AML with myelodysplasia-related changes (AML-MRC) (7), t(11;19) (4), inv(16) (2), t(6;9) (1), therapy-related (1), AML-NOS (11), and NM-AMLs could be subclassified as therapy-related (1), AML-NOS (4). IHC CD14 quantitation as a % of nucleated cells was performed over 6 40X fields with the aid of an image analysis program (Image J; http://rsbweb.nih.gov/ij/). CD33, MPO, & CD123 positive cells were evaluated semi-quantitatively & graded 0-3+.
Results: There was good correlation between CD14% by IHC & FCM (r=0.7). By IHC and FCM, the mean % of CD14+ cells was significantly higher in CMML as compared to the non-neoplastic cases (p<0.01).

Average CD14%

Differences in mean % IHC CD14+ cells in Mo-AML versus CMML were not significant.Diffuse CD123+(2 or 3+) was only seen in AML (10/31 cases).Scattered CD123+ cells (1+) were seen in 6/31 AMLs, 13/18 CMMLs, & 9/10 non-neoplastic cases. MPO was wk/negative (1 or 0) in 9/26 AMML cases, but all were CD33+ (≥2+). 4/5 NM-AML cases were MPO wk/negative but 3 were also wk/negative for CD33. MPO/CD33 expression were concordent in all CMML cases.
Conclusions: Increased CD14 IHC+ cells may be useful in distinguishing CMML from non-neoplastic cases,but not in distinguishing between CMML and Mo-AML. Scattered CD123+ cells were seen in both neoplastic and non-neoplastic cases, however,diffuse positivity (2 or 3+) was only identified in AML cases.CD33 is a useful diagnostic adjunct in MPO negative Mo-AML cases.
Category: Hematopathology

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 189, Monday Morning


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