BOB.1 expression in a variety of established B-cell lines, representing different stages of B-cell development, has suggested a constitutive, B-cell-specific expression pattern. LP cells in nodular lymphocyte predominant Hodgkin lymphoma, because they are germinal center-derived, are consistently immuno-positive for BOB.1. Conversely, only some cases of classical Hodgkin lymphoma show BOB.1 immuno-reactivity within the Hodgkin and Reed-Sternberg cells.Expression of BOB.1 has been reported in follicular center cell lymphoma, diffuse large B-cell lymphoma and some cases of acute myeloid leukemia.B-CLL, marginal zone lymphoma, and mantle cell lymphoma may show weak to moderate immunoreactivity.