24-OR

Abstract

Aim Flow cytometric crossmatch (FCXM) has increasingly become the preferred method of crossmatching due to its increased sensitivity and specificity compared to the standard complement dependent cytotoxicity (CDC)-based methods. Here we report a case of undiagnosed lymphoma identified during a routine deceased donor final FCXM. Methods FCXM was performed on a Becton Dickinson FACSCalibur flow cytometer using pronased donor peripheral blood mononuclear cells. Staining included PerCP-CD3 for T-cells, PE-CD19 for B-cells, and FITC-goat anti-human IgG for the detection of surface-bound antibody. Results Donor was a 56-year-old Caucasian male admitted for cardio-pulmonary arrest and was evaluated for donation after circulatory death (DCD). His past known medical history included developmental delay, mental retardation, hypothyroid and general seizure disorder. During the final crossmatch of 11 renal recipient candidates, while the gated lymphocyte population displayed a typical FSC/SSC profile, a subpopulation of dimly stained CD19+ B-cells (28% dimmer) was observed with every serum crossmatched. This abnormal B-cell population constituted >50% of the entire CD19+ population and also displayed an elevated baseline FITC-IgG staining (31% brighter), indicating a denser-than-normal surface IgG profile. The T-cell population appeared normal for CD3 and FITC-IgG staining. Further immunophenotyping showed that this B-cell population was normally bright for CD20 and CD45; negative for CD5, CD10 and CD23; indeterminate for CD11c and CD38; and light chain staining displayed a Kappa restriction. Taken together, the immunophenotypic profile suggested a diagnosis of some form of mature B-cell non-Hodgkin’s lymphoma. This donor case was subsequently turned off. Conclusions This case report illustrates the possibility of identifying undiagnosed hematological malignancies using the conventional histocompatibility crossmatch setup even with only limited lymphocyte markers.