 However, patients whose major contributing factor to PBL-development is EBV-positivity often present with, and continue to have, a significantly less aggressive disease than other patients with PBL.It is similarly clear that, on average, elderly patients (>68 years) likewise present with, and continue to have, a significantly less aggressive disease.Microscopic examination of involved PBD masses and infiltrates generally reveals diffuse proliferations of immunoblast-like cells with prominent features of plasma cells, i.e.