title: Focal and segmental glomerulosclerosis: clinical and kidney biopsy correlations.
abstract: BACKGROUND
  Primary focal segmental glomerulosclerosis (FSGS) is a common glomerular disease in adults and ranks among the top causes of a primary glomerular disease causing end-stage renal disease (ESRD). Primary FSGS is, however, a diagnosis of exclusion and distinction between primary versus secondary FSGS is not always obvious, resulting in a number of patients with secondary FSGS undergoing unnecessary immunosuppressive therapy.
  
  
  METHODS
  We reviewed the Mayo Clinic Renal Pathology Database for patients with a diagnosis of FSGS on native renal biopsy and divided the patients into nephrotic syndrome-associated (NS-associated) and non-nephrotic syndrome-associated (NNS-associated) FSGS as a first approximation followed by dividing the lesion according to the degree of foot process effacement (FPE) on electron microscopy (EM) examination.
  
  
  RESULTS
  A total of 41 patients with FSGS with complete evaluation were identified. Of these, 18 were classified as having NS and 23 were classified as having NNS. Baseline characteristics (age, gender, body mass index, serum creatinine and hematuria) were not different between the groups. All of the patients with NS showed diffuse FPE ranging from 80 to 100% (mean 96%). On the other hand, of the 23 patients in the NNS group, 22 had segmental FPE and showed patchy effacement, with all cases showing 20-60% FPE (mean of 48%).
  
  
  CONCLUSIONS
  Adult patients presenting with NS, an FSGS lesion on LM, extensive FPE (≥80%) on EM examination and no risk factors associated with secondary FSGS are likely to have primary FSGS. Conversely, the absence of NS in a patient with segmental FPE on EM strongly suggests a secondary FSGS. Dividing FSGS into the presence or absence of NS together with the degree of FPE on EM examination is more helpful as it provides a more practical way to separate patients into cases of primary versus secondary FSGS.
authors.affiliation: Division of Anatomic Pathology , Mayo Clinic College of Medicine , Rochester , MN , USA.
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Sethi
authors.affiliation: Division of Nephrology and Hypertension , Mayo Clinic College of Medicine , Rochester, MN , USA.
authors.forename: Ladan
authors.initials: L
authors.lastname: Zand
authors.affiliation: Division of Anatomic Pathology , Mayo Clinic College of Medicine , Rochester , MN , USA.
authors.forename: Samih H
authors.initials: SH
authors.lastname: Nasr
authors.affiliation: Geffen School of Medicine School at UCLA , Mayo Clinic College of Medicine , Rochester , MN , USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Glassock
authors.affiliation: Division of Nephrology and Hypertension , Mayo Clinic College of Medicine , Rochester, MN , USA.
authors.forename: Fernando C
authors.initials: FC
authors.lastname: Fervenza
keywords: focal and segmental glomerulosclerosis; nephrotic range; nephrotic syndrome; primary; secondary