348P - In-depth molecular analysis in the diagnosis of lymphomas with lymphoplasmacytic differentiation may provide a more precise diagnosis and rational treatment allocation

Background

We performed a molecular analysis of formalin-fixed paraffin embedded and decalcified bone marrow trephine biopsies of primary diagnoses and follow-up biopsies of 41 patients with lymphomas with lymphoplasmacytic differentiation (LPLs) to enable a more precise diagnosis and to describe potentially prognostic and therapeutic relevant mutations.

Methods

Analysis was performed by means of a commercially available Lymphoma Panel (Lymphoma Solution, SophiaGenetics). Results were correlated with clinical and pathological parameters including pathological diagnosis, immune phenotype, volume of infiltration, infiltration pattern, and number of mast cell.

Results

Our group finally covered a spectrum of lymphomas with plasmacytic differentiation ranging from Waldenstroems macroglobulinaemia (WM), comprising the largest group, to small-B-cell lymphomas with plasmacytic differentiation (SBCL-PC) to IgM myeloma (MM). The most helpful diagnostic criteria were a combination of morphology including infiltration pattern and mast cell count, and immune phenotype. MYD88 mutation was present in nearly all WM but also in 50% of the SBCL-PC. Only MM were consistently negative for the mutation. We found that known oncogenic mutations, such as TP53 are already detectable early in the course of the disease and were associated with a significantly shorter PFS. In addition, we report on a novel BIRC3 frameshift mutation in a case of a progressive WM.

Conclusions

Our data indicate that patients with LPL might benefit from a thorough pathological work-up and a detailed molecular analysis in terms of a precise diagnosis and a more targeted treatment allocation.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The Authors.

Funding

Roche.

Disclosure

All authors have declared no conflicts of interest.