Podocyte infolding glomerulopathy: a rare entity

A female in her 30s presented with worsening lower limb swelling. Her past medical history included primary hypothyroidism, learning difficulties and an atrial septal defect. She was found to have a nephrotic syndrome and was referred to Nephrology with worsening oedema and proteinuria. The initial blood workup showed a mildly elevated serum C3 level and a polyclonal increase in serum IgM level. Renal biopsy was performed which on H&E demonstrated glomeruli with mild mesangial hypercellularity and prominent capillary walls. Electron microscopy showed severe podocyte foot processes effacement and unusual podocyte inclusions which were protruding into the glomerular basement membrane. She was diagnosed with minimal change disease. The exact nature of these peculiar podocyte inclusions remained unknown until the entity of podocyte infolding glomerulopathy (PIG) was published in the English language literature in 2008. In retrospect, we believe the changes observed in our case were due to PIG.