Concurrence of renal amyloidosis and membranous nephropathy: a case series and literature review

BACKGROUND: Amyloidosis is a group of heterogeneous diseases characterized by the deposition of amyloid fibrils in various organs and tissues. Membranous nephropathy (MN) is one of the most common causes of nephrotic syndrome in adults. CASE PRESENTATION: We report three cases of early-stage MN occurring concurrently with distinct types of renal amyloidosis: apolipoprotein A-I (AApoA-I) amyloidosis, leukocyte chemotactic factor 2 (ALECT2) amyloidosis, and monoclonal immunoglobulin light-chain (AL) amyloidosis. Each case represents a different pathogenic mechanism, therapeutic approach, and clinical prognosis. CONCLUSIONS: These cases underscore the pivotal role of renal pathology in the accurate diagnosis of patients with coexisting amyloidosis and MN. Correct classification of renal amyloidosis is essential for guiding therapy and predicting outcomes. When amyloidosis coexists with MN or other potentially treatable renal diseases, therapeutic decisions should prioritize the condition with the greater potential for organ damage or the one most responsive to available treatment.