Chapter 6: Idiopathic focal segmental glomerulosclerosis in adults

BACKGROUND The classical description of FSGS includes segmental increase of mesangial matrix with obliteration of the capillaries, sclerosis, hyalinosis, foam cells, and segmental scarring, and adhesion between the glomerular tuft and Bowman’s capsule. A recently proposed pathology classification has pointed to the existence of nonsclerotic forms of FSGS. There has been a marked increase in the number of known underlying causes for the lesion of FSGS over the last 10–20 years. Perhaps a consequence of this has been that the incidence, the age of onset, and the clinical presentation have also dramatically altered over this timeframe. FSGS is now one of the most common patterns of glomerular injury encountered in human kidney biopsies, and it is the most common cause of proteinuria in the African-American and US Hispanic populations.