Podocyte infolding glomerulopathy; report of the first case in Latin America and review of the literature

Abstract

Background: Podocyte infolding glomerulopathy (PIG) is a condition of uncertain origin, frequently associated with autoimmune diseases. Its specific treatment and clinical course are unknown. It is characterised by thickening of the capillary walls due to the presence of non-argyrophilic intramembranous bubbles similar to those found in membranous glomerulopathy, but without electron-dense deposits of immune complexes in the ultrastructure, where translucent microspheres generated by invagination of the podocyte cytoplasm into the basement membranes are observed.

Objectives: Generally reported in young females patients. To date, few cases in Asian patients have been reported. Our case is the first to be reported in a Latin American Caucasian patient.

Methods: A 38-year-old woman with SLE. In 2014 she presented with nephrotic syndrome empirically treated with corticosteroids (CO) and intravenous cyclophosphamide with good response. She had a relapse in April 2015 with normal renal function and no extrarenal lupus activity, so she was referred to our hospital to be biopsied.

Results: The biopsy reported focal segmental glomerular sclerosis without deposits of immune complexes in the immunofluorescence. However, methenamine silver staining revealed clear spaces in the capillary walls accompanied by marked podocyte alterations. On electron microscope study, numerous aggregates of microvesicular and cylindrical ultrastructures bound to the membranes were observed, without evidence of dense deposits, and diffuse effacement of pedicel foot processes, confirming the suspected diagnosis.

Conclusions: This is the first reported case of what can be considered a new pathological glomerular entity in a Latin American Caucasian patient, whose clinical course and therapy are still unknown.

Keywords: Glomerular basement membrane; Glomerulonefritis; Glomerulonephritis; Glomerulopatía membranosa; Glomerulopatía por invaginación podocítica; Membrana basal glomerular; Membranous glomerulopathy; Microesferas; Microestructuras; Microspheres; Microstructures; Podocyte infolding glomerulopathy.