الفهرس 
IntroductionOnly 14 pages are availabe for public view
Abstract
Primary FSGS is responsible for approximately 10%–15% of the cases of NS in children and 20%–30% in adults (Kambham, 2018). The incidence of primary FSGS has grown and it is now the leading cause of steroid resistant nephrotic syndrome (SRNS) in both children and adults. Primary FSGS progresses to ESRD in about 50% of patients within 10 years of clinical onset (Mason, 2014). It accounts for about 4% of all end stage renal diseases, so steroids alone are not enough; in addition it needs more intense immunosuppression for its management (Kambham, 2018).
MCD is the most common cause of idiopathic nephrotic syndrome in children accounting for 80%–90% of cases, but in adults it represents only about 10%–15% of cases being the third cause (Olson, 2015). MCD cases usually do not develop chronic kidney disease; in contrast 95% of MCD patients undergo complete remission on steroid administration (Kambham, 2018).
Because of similar clinical presentation and different management and prognosis, it is important to differentiate between FSGS and MCD, the final diagnosis is usually made by the pathologists (Maas et al., 2016). The distinction between early FSGS versus MCD may be difficult, because of focal and segmental nature of the disease particularly when biopsy samples contain only a few glomeruli or when glomerular injury is at an early stage or when the sample is superficial and doesn’t involve deep cortex (Smeets et al., 2014). Biopsy findings of focal tubular atrophy and interstitial fibrosis should also prompt a more exhaustive search for unsampled FSGS even with normal looking glomeruli (especially with a small biopsy specimen) (Vivarelli et al 2017).
Many studies revealed that parietal epithelial cells (PECs) are crucially involved in the development of glomerulosclerosis (Smeets et al., 2014).
Claudin-1 is a transmembrane protein physiologically found in tight junctions that is expressed exclusively by PECs within the glomerulus (Fritzsche et al., 2008). Normal and non-sclerotic glomeruli will show immunostaining of this marker exclusively at the Bowman’s capsule. In contrast, in FSGS lesions this marker will also stain the PECs in a visceral location.
The aim of this study is to differentiate early FSGS from MCD by detection of activated parietal epithelial cells in early sclerotic lesions using Claudin-1 immunohistochemical staining.
This study included 48 cases ; 28cases diagnosed as MCD and 20 cases diagnosed as early FSGS collected from Pathology lab and Electron Microscopy unit at Ain Shams University Specialized Hospital during the period from 2011-2016.
Our results revealed a highly statistically significant correlation between claudin-1 expression and the detection of small glomerular segmental sclerotic lesions, it succeeded to detect missed sclerotic lesions in (39.28%) of the biopsies initially diagnosed as MCD confirming that these lesions were missed early FSGS in the initial biopsy.
Statistically significant correlation was also detected between claudin-1 expression and main presenting symptom for MCD at time of biopsy, 63.64% of positive cases were presented mainly by steroid resistant nephrotic syndrome which confirms that FSGS cases which are missed in the initial biopsy are often steroid resistant.
No Statistically significant correlation could be detected between claudin-1 expression and patient’s age or sex.
Although 36.36% of the positive MCD cases showed focal tubular changes, and also 27.27% of these cases were associated with glomerulomegally, yet no statistically significant correlation could be detected between claudin-1 expression and these findings .This may be owed to that only few number of included cases showed these parameters.
The clinical implications of our findings include the possible use of claudin-1 immunostaining as a diagnostic marker to differentiate between confusing cases of MCD and early FSGS.