Bcl-6 protein expression, and not the germinal centre immunophenotype, predicts favourable prognosis in a series of primary nodal diffuse large B-cell lymphomas: a single centre experience.

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease. The immunohistochemistry-based algorithms for the determination of the cell of origin of DLBCL have been proposed as a practical method to validate and surrogate results obtained by gene expression profiling. We studied 71 patients with primary nodal DLBCL at diagnosis, who received anthracycline-based therapy with or without rituximab. Immunohistochemistry was performed using anti-CD10, Bcl-6, MUM1 and Bcl-2 antibodies in order to assess the ontogenic profile of neoplastic cells and to verify its relation with clinical outcome. Survival data were analysed using an explorative Cox model. The immunohistochemistry-based algorithms for the determination of the cell of origin of DLBCL were not associated with prognosis. By contrast, Bcl-6 expression was associated with a longer lymphoma-free survival while immunoreactivities for MUM1 or Bcl-2 were not significantly related to patient outcome. Bcl-6 expression alone proved to be a prognostic marker in primary nodal DLBCL and seemed to be more reliable to predict clinical outcome in these disorders than the immunohistochemical algorithms for the detection of the germinal centre/non-germinal centre immunophenotype.