Morphological sub-classification of focal segmental glomerulosclerosis and their Clinio-pathological correlation: Experience from a tertiary care centre

Background:  The word focal segmental glomerulosclerosis (FSGS) is used to describe the common morphologic pattern occurring due to various progressive renal diseases and also to describe the primary idiopathic lesion of FSGS. Here, we are documenting the distribution of various types of FSGS and associated morphological lesion in the renal biopsy which may help to define the underlying cause of FSGS Methods: Total 47 cases of FSGS were retrieved from the archives and classified according to Agati’s classification. Acid Fuchsin Orange G (AFOG) stain was done to look for immune deposits. Direct immunofluorescence (DIF) was done in few cases. Result:  FSGS - NOS was most common variant followed by perihilar and cellular variant. Focal segmental mesangial cell proliferation and GBM thickening were commonly found in NOS variant. Interstitial non caseating granulomas and mononuclear cell infiltrate admixed with neutrophils were more frequent in perihilar FSGS. Many cases earlier diagnosed as perihilar or tip lesion, latter turned out to be NOS variety on serial sections. AFOG stain revealed mesangial deposits in 70.22% cases, suggesting immunological aetiology of the disease instead of primary FSGS.  DIF was performed in seven cases and all showed predominant IgM deposits in mesangium. Conclusion: Typing of FSGS should be done on the serial sections, especially of tip lesion. Most of FSGS cases turned out to be secondary to other glomerular disease instead of idiopathic variant. So, FSGS appear to be a morphological descriptor of various chronic renal diseases instead of being a separate entity.