CD5 expression in marginal zone lymphoma does not predict inferior outcome and has similarities to indolent lymphomas

• Besides BM involvement, there were no differences in baseline characteristics, outcome or transformation to DLBCL between CD5+ vs CD5- MZL

• CD5+ MZL has similarities to CLL in terms of immunophenotype, IGVH mutational status, overall survival, and time to first systemic therapy

The prognostic relevance of CD5 expression in marginal zone lymphoma (MZL) remains poorly characterized. We aimed to compare baseline characteristics and outcomes of patients with CD5+ MZL and CD5- historical matched controls. We hypothesized that patients with CD5+ MZL may have similarities to other CD5-expressing B-cell lymphomas, which may be informative when considering alternative therapeutic approaches for this MZL subgroup. We retrospectively analyzed 64 patients with CD5+ MZL and 137 CD5- MZL controls matched on age at diagnosis and sex. The CD5+ and CD5- cases did not differ in terms of MALT-IPI or incidence of nodal involvement. Bone marrow involvement was significantly more frequent in the CD5+ patients than in CD5- patients (67.5% vs 47.2%, p = 0.048). Mutated IGHV was more common in the CD5+ patients (80.0%) compared to the CD5- patients (64.0%), but this association was not significant (p = 0.327). Overall survival was calculated until death from any cause, disease-specific survival until lymphoma-related death, and time from diagnosis to first treatment was calculated either considering all interventions or only systemic treatments. None of these outcomes were associated with CD5 expression.