Podocytes Intracytoplasmic Dense Inclusions: Are They Associated with Subepithelial Dense Deposits? An Ultrastructural Study

INTRODUCTION: Podocytes play a crucial role in health and disease. They participate in clearing the filtration barrier by removing accumulated proteins. It is proposed that podocytes have the ability to remove immune complexes and internalize them in the cytoplasm. AIMS: The purpose of this study is to review certain immune complex glomerulonephritis (GN) types and illustrate ultrastructural details of podocytes intracytoplasmic dense inclusions (ICDIs) if present. MATERIALS AND METHODS: A retrospective ultrastructural study of podocytes was conducted to detect cytoplasmic inclusions. The study cases (n = 148) include GN types with subepithelial dense deposits such as membranous GN, postinfectious GN (PIGN), and lupus nephritis. RESULTS: Podocytes ICDIs are detected ultrastructurally in 48 of 148 cases, mostly with PIGN; their morphology resembles the subepithelial dense deposits of the corresponding case. CONCLUSIONS: Podocytes ICDIs represent internalized immune complexes from the adjacent subepithelial dense deposits, suggesting a clearance method of the glomerular basement membrane by podocytes.