B-cell lymphoproliferative syndrome and peripheral blood CD20+ cells expansion after hematopoietic stem cell transplantation: association with fludarabine and anti-thymocyte globulin containing conditioning regimen.

Fifty-eight patients who received hematopoietic stem cell transplants during a 3-year period in our unit were followed for the symptoms of posttransplant B-cell lymphoproliferative syndrome (B-cell PTLD). Three cases showed lymph node enlargement; in 14, there was an excess of B cells in the blood. Histochemical staining of lymph nodes revealed CD20+ cell expansion in two cases, and in one, CD38+ and CD138+ cells. Kappa and lambda staining revealed poly- or oligoclonal expansion, which was characterized by the presence of Ki67+ cells in 10% to 50% of cells. In 14 cases, an excess of CD20+ cells were observed in blood. Clinical analysis revealed that patients with B-cell expansion in blood and/or in lymph nodes frequently showed fever and that some subjects displayed arthralgia, hemolytic anemia, and hepatitis. LMP-1-positive cells were observed in lymph nodes as well as EBV copies, whereas only a proportion of patients with the excessive CD20+ cells in blood were EBV positive. Notably, lymph node enlargement and CD20+ blood excess occurred significantly more frequently among patients receiving a Fludarabine (Flu) and anti-thymocyte globulin (ATG) conditioning regimen than those whose treatment lacked Flu independent of whether they received ATG (0.80 vs 0.44; P =.036).