P0288CLINICOPATHOLOGICAL FEATURES OF FOCAL AND SEGMENTAL GLOMERULOSCLEROSIS: STEPS FOR AN ACCURATE CLASSIFICATION - A SINGLE CENTRE CASE SERIES
Authors: Santos Afonso , Campos Pedro , Lima Anna , Gaspar Ana , Brás Catarina , Soto Karina 
Published: June 2020

Abstract

Background and Aims
Focal and segmental glomerulosclerosis (FSGS) is a histological pattern that is defined by the presence of segmental sclerosis of at least one glomerulus in the kidney biopsy. However, the etiological classification of this lesion remains challenging in clinical practice. FSGS can be divided into primary/idiopathic, genetic or secondary. Nowadays here is no biochemical marker that allows clinicians to distinguish between these categories nor a pathognomonic feature associated to a particular subtype of FSGS. Also, genetic testing is not suitable for all patients. Although it is crucial to determine the cause of FSGS, this is not easily done in clinical practice. Herein we present a series of patients with histologic diagnosis of FSGS in which clinical and histological criteria were applied in order to establish the etiologic classification of FSGS.

Method
A retrospective analysis of 359 patients who performed kidney biopsy from January 2010 to December 2018 was performed. Patients with histological features of FSGS were identified. Clinical, laboratorial and pathological data were collected, including treatment and outcome. Patients were classified as having genetic FSGS if they accomplished at least one of the following: a) nephrotic syndrome resistant to corticosteroids; b) non-nephrotic proteinuria or nephrotic syndrome with normal serum albumin; c) non-nephrotic proteinuria or nephrotic syndrome with focal foot process effacement or d) non-nephrotic proteinuria with diffuse foot process effacement. The remaining patients were classified as secondary FSGS (if they presented a disease known to be associated with FSGS) or primary FSGS. Each group was divided according to treatment with corticoid, other immunosuppressive agents or and RAAS blockage. Renal outcomes were assessed (progression to ESKD).

Results
A total of 359 kidney biopsies were performed between January 2010 to December 2018, 66 with a histological pattern of FSGS. 65% (N=43) were males, 71% (N=47) were Caucasian and 23% (N=15) were black. 74% (N=49) had past medical history of hypertension, 26% (N=17) diabetes mellitus and 5% (N=3) had HIV. The majority of patients were classified as having secondary FSGS (52%, N=34), 23% (N=15) were classified as primary and as 25% (N=17) genetic/idiopathic. From the genetic group 58.8% (N=10) were treated with corticoid, 12% (N=2) with other IS agents and 71% (N=12) with ACE/ARB. 29% (N=5) evolved to ESKD (median time to dialysis 11 IQR 1-30).
In the primary FSGS group 40% (N=6) were treated with corticoid, 7% (N=1) with other IS agents and 80% (N=12) with ACE/ARB. 27% (N=4) evolved to ESKD (median time to dialysis 0 months, IQR 0-33).
In the genetic group 59% (N=10) were treated with corticoid, 12% (N=2) with other IS agents and 71%(N=12) with ACE/ARB. 29% (N=5) evolved to ESKD (median time to dialysis 11 months, IQR 1-30).

Conclusion
FSGS is a very prevalent glomerular disease and its correct etiologic classification aids in better treatment choice. Although its etiology is not straightforward in most of the patients, some clinical and histological characteristics aid in FSGS classification.