Membranous glomerulonephritis associated with splenic marginal zone lymphoma mimicking multiple myeloma.

Glomerulonephritis may complicate the course of a wide variety of malignant diseases. However, there are relatively few reports of membranous glomerulonephritis (MGN) in patients with non-Hodgkin lymphoma (NHL). We describe for the first time a case of MGN associated with splenic marginal zone lymphoma with extreme plasmacytic differentiation and bone marrow infiltration mimicking multiple myeloma. We also reviewed the literature and summarize the clinical-pathological findings and the mechanisms involved in NHL-induced MGN. Our current case highlights the importance of a quick and correct diagnosis of the underlying disease and the value of a thorough physical examination. Clinicians should be aware of the possibility of an underlying hematologic malignancy in such cases, particularly in elderly patients with renal biopsy that shows the presence of atypical histology.