The rare phenomenon of glomerulonephritis presentation in extra-nodal marginal zone lymphoma: summary of two cases and review of the literature.

Paraneoplastic glomerulonephritis (GN) has been reported in non-Hodgkin lymphoma (NHL), Hodgkin Lymphoma (HL), and chronic lymphocytic leukemia (CLL). Despite descriptions in NHL, very few reports have been documented in marginal zone lymphoma (MZL). In this article, we review the literature of currently known cases of MZL-associated GN and we detail two cases of patients with extra-nodal MZL (EMZL) who both presented with renal failure, fluid overload, and proteinuria which were attributed to GN after a renal biopsy. We discuss the pathology of each renal biopsy in depth and how the diagnosis of GN was made, along with potential mechanisms of how EMZL led to GN. We also discuss the treatments each patient received and whether this led to the resolution of their GN. Both cases highlight the importance of maintaining a high index of suspicion for this paraneoplastic syndrome when patients present with signs or symptoms of renal failure, proteinuria or hematuria, or potential renal involvement on imaging. In these cases, a renal biopsy should be pursued to confirm the diagnosis, and treatment should be tailored accordingly.