[1561] CD38 Expression Density in the Phenotypic Differential Diagnosis of Mantle Cell Lymphoma, CD38+ Chronic Lymphocytic Leukemia and Marginal Zone Lymphoma

Kandi Stallings, Sumaia El Amin, Samuel Pirruccello. University of Nebraska Medical Center, Omaha, NE

Background: The surface density of CD38 expression varies predictably during normal B-cell differentiation. More importantly, CD38 expression density is recapitulated in B-cell lymphoproliferative disorders (B-LPD) and has significant utility in B-LPD detection and classification by flow cytometry. For this study, we characterized the patterns of CD38 density in two prognostically different but phenotypically similar B-cell lymphomas. We hypothesized that CD38 density would be higher in mantle cell lymphoma (MCL) on average, in comparison to CD38+ chronic lymphocytic leukemia (CLL) and by extension that CD38 density would be a useful additional marker in the differential diagnosis of these two disorders.
Design: Retrospective analysis of archived listmode files of bone marrow samples from patients with MCL and CD38+ CLL was performed. Cases were identified from the Co-Path database at our institution for years 2005 to 2011. Cases with confirmed morphological diagnoses and flow immunophenotyping studies performed by our laboratory were selected. A third group consisting of marginal zone lymphoma (MZL) cases, which should exhibit absent or low density CD38 expression, was also included. Logarithmic displays of CD20 by CD38 expression of CD19 gated LPD cells were used to determine the CD38 mean fluorescence intensity (MFI) values on a four decade log scale. Statistical differences in average CD38 MFIs were compared between the three LPD groups using Student's t test.
Results: Thirty-four cases of MCL, 34 cases of CD38+ CLL and 26 cases of MZL were selected. Five of the 34 cases of MCL (15%) were CD38 negative (MFI<1.0) and were excluded. The mean±s.d. CD38 MFIs were 9.8±6.2, 4.0±4.1 and 2.8±4.8, for MCL, CLL, and MZL respectively. Mean CD38 density was significantly higher for MCL in comparison to CLL (P<0.0001) and MZL (P<0.0001). There was no statistically significant difference in CD38 expression density between MZL and CD38+ CLL (P=0.30).
Conclusions: CD38 expression density in the context of other B-cell markers is highly informative in the classification of B-cell lymphoproliferative disorders. CD38 expression density is significantly higher in MCL in comparison to CD38+ CLL and provides additional phenotypic detail in distinguishing these two disorders. MZL exhibits a CD38 density profile consistent with a memory cell derivation and 69% of cases (18/26) had an MFI<1.0.
Category: Hematopathology

Monday, March 19, 2012 1:00 PM

Poster Session II # 198, Monday Afternoon


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