EDTA-dependent lymphoagglutination in persistent polyclonal B-cell lymphocytosis

Abstract

A 38-year-old female smoker was referred for assessment of a persistent polyclonal B-cell lymphocytosis (PPBL). She complained of profound asthenia and arthralgia. There was no palpable enlargement of lymph nodes, liver or spleen. Laboratory investigations showed moderate isolated lymphocytosis (4AE9 · 10/l) with 3% binucleated cells, increased polyclonal immunoglobulin (Ig) M (8AE2 g/l), HLA-DR7 phenotype and the presence of an abnormal karyotype: 47,XY,+i(3)(q10)[4]/46,XY[29]. Peripheral blood immunophenotyping demonstrated a polyclonal increase in the B-cell pool with IgM, IgD, CD19, CD20, CD21, CD22, CD24, CD27, CD40, CD79b and FMC7 positivity and CD5, CD10, CD23, CD25, CD30, CD34, CD38, CD43, CD54, CD122, CD138 and CD154 negativity, in keeping with a memory B-cell origin. In addition, clumps of lymphocytes including binucleated cells were observed under the microscope (left), but were absent when a specimen was taken into citrate (right), suggesting an artifactual EDTA-dependent lymphoagglutination. PPBL occurs mainly in middle-aged female smokers, presenting with a moderate chronic lymphocytosis with atypical binucleated lymphocytes comprising 1–10% of the lymphocytes and increased polyclonal serum IgM. The B cells are polyclonal with kappa and lambda light-chain expression and no clonal rearrangement of the immunoglobulin heavy chain genes. The cytogenetic profile includes an additional isochromosome for the long arm of chromosome 3, genetic instability and premature chromosome condensation. About 3% of patients develop lymphoma. Lymphoagglutination is a rare EDTA-dependent phenomenon; the use of other anticoagulants (citrate or heparin) avoids this artefact in nearly all cases. It occurs most often in B-cell lymphoproliferative disorders, particularly marginal zone lymphoma. The occurrence in PPBL may be attributed to the likely origin of these cells from the splenic marginal zone.