Membranous Nephropathy Associated with Atheroembolism

Membranous nephropathy (MN) is one of the most common biopsy diagnoses in adults, and it has been associated with chronic infections, autoimmune diseases, malignancies, and drugs. However, MN associated with cholesterol crystal emboli has never been reported. Here we present a patient with MN as an unusual manifestation of atheroembolism. A 75-year-old man with worsening renal function after catheter ablation developed moderate proteinuria and underwent a renal biopsy. Findings on light, immunofluorescence, and electron microscopy were all compatible with membranous nephropathy. Moreover, one occluded interlobular artery contained a pathognomonic, biconvex, needle-shaped cleft, which indicated a cholesterol crystal emboli. The degree of proteinuria was in parallel with the number of eosinophils, which indicated a close relationship between MN disease activity and renal atheroembolism. Hypereosinophilic syndrome secondary to atheroembolism may cause MN; thus, corticosteroid therapy was likely to be effective.