Benign hematogone-rich lymphoid proliferations can be distinguished from B-lineage acute lymphoblastic leukemia by integration of morphology, immunophenotype, adhesion molecule expression, and architectural features

Distinction of normal B-lymphoid proliferations including precursors known as hematogones from acute lymphoblastic leukemia (ALL) is critical for dise ase management. We present a multiparameter assessment of 27 bone marrow sa mples containing at least 25% hematogones (range, 25%-72%) by morphologic r eview We used flow cytometry to evaluate B-cell differentiation antigen and adhesion molecule expression and immunohistochemistry on clot sections to evaluate architectural distribution. Flow cytometry revealed that intermedi ately differentiated cells (CD19+, CD10+) predominated, followed infrequenc y by CD20+, surface immunoglobulin-positive cells, with CD34+, terminal deo xynucleotidyl transferase (TdT)-positive cells as the smallest subset. Adhe sion molecules (CD44, CD54) were expressed more heterogeneously compared wi th expression in acute lymphoblastic leukemia. Immunohistochemistry repeale d that CD34+, TdT-positive cells were dispersed without significant cluster ing, while CD20+ cells exceeded CD34/TdT-positive cells in 24 of 25 cases. This multidisciplinary study demonstrates that hematogone-rich lymphoid pro liferations exhibit a spectrum of B-lymphoid differentiation antigen expres sion with predominance of intermediate and mature B-lineage cells, heteroge neity of adhesion molecule expression, and nonclustered bone marrow archite ctural distribution.