Saudi Journal of Kidney Diseases and Transplantation

LETTER TO THE EDITOR
Year
: 2013  |  Volume : 24  |  Issue : 4  |  Page : 822--823

Histomorphological classification of focal segmental glomerulosclerosis: A critical evaluation of the clinical, histologic and morphometric features


Muhammed Mubarak 
 Professor of Pathology, Histopathology Department, Sindh Institute of Urology and Transplantation, Karachi - 74200, Pakistan

Correspondence Address:
Muhammed Mubarak
Professor of Pathology, Histopathology Department, Sindh Institute of Urology and Transplantation, Karachi - 74200
Pakistan




How to cite this article:
Mubarak M. Histomorphological classification of focal segmental glomerulosclerosis: A critical evaluation of the clinical, histologic and morphometric features.Saudi J Kidney Dis Transpl 2013;24:822-823


How to cite this URL:
Mubarak M. Histomorphological classification of focal segmental glomerulosclerosis: A critical evaluation of the clinical, histologic and morphometric features. Saudi J Kidney Dis Transpl [serial online] 2013 [cited 2020 Sep 22 ];24:822-823
Available from: http://www.sjkdt.org/text.asp?2013/24/4/822/113908


Full Text

To the Editor ,

I have read with great interest the article by Das et al published in a recent issue of your journal. [1] The authors have analyzed the clinicopathological and the glomerular morphometric features of the histological variants of focal segmental glomerulosclerosis (FSGS). It is worth reiterating here that FSGS is not a single disease; rather, it represents a descriptive clinicopathological diagnosis characterized clinically in most cases by nephrotic range proteinuria and histologically by the presence of segmental sclerotic lesions involving some but not all of the glomeruli. [2] The lesion may be primary (idiopathic) or secondary to various etiologic agents and the pathogenetic mechanisms. [2] Notably, the prevalence of FSGS has increased significantly in the biopsy series in the recent past throughout most parts of the world. Coupled with this increase in the incidence, different histological variants of FSGS have also been recognized, with considerable confusion over the terminology and classification. [3],[4],[5],[6],[7] In 2004, a group of renal pathologists proposed a consensus-based pathological classification system for FSGS based solely on light microscopic (LM) examination, popularly known as the Columbia classification. [2] According to this classification, five histologic variants of FSGS are described; FSGS, not otherwise specified (NOS), perihilar variant, cellular variant, tip variant and collapsing variant. [2]

Many studies have been published in the literature on the prevalence and clinicopathological characteristics of different histologic variants of FSGS. [3],[4],[5],[6],[7] Some of these studies have also studied the clinical relevance of this classification. The study by Das et al also represents such an attempt from a single referral center in India. [1] According to the authors, this is the second study from India. We have also published our experience on FSGS variants in adult patients and there are some differences in the prevalence and clinicopathologic characteristics in these studies. [7] In addition, there are many points in the subject article that need clarification or explanation to better understand the results obtained.

There is no information on the thickness of sections or the number of serial sections examined. These technical pre-requisites are important if the Columbia classification is to be applied properly for its intended utility. Multiple variants may co-exist on the different serial sections of the same biopsy, requiring examination of at least 15 serial sections and a hierarchical approach to address this intra-lesional heterogeneity.The authors state in the results that all patients presented with steroid-resistant nephrotic syndrome (SRNS), which is incorrect, as the indications for renal biopsy in adults do not require prior steroid therapy. Of course, the biopsy policies vary from center to center. If the authors have an explanation otherwise, they must clarify this point. In addition, this finding is incongruent with the prevalence of nephrotic range proteinuria provided for different variants in [Table 1].A very high prevalence of perihilar variant in pediatric cases is difficult to understand. In this context, it is worth knowing whether the criteria of

gt;50% perihilar location of segmental lesions was also fulfilled? It is well known that there can be marked overlap between the perihilar and the NOS variants. [6]The methodology and the strict definition of visceral epithelial prominence and the glomerular area are also not detailed sufficiently for these to be reproduced easily by other researchers.Unfortunately, all the studies from this region, including the subject and our study, are cross-sectional surveys. There is no information on the treatment, clinical course and the outcome. These severely hamper the primary objective of testing the clinical relevance of the classification.The comment that the Columbia classification restricts the hypercellularity to the endocapillary compartment in the cellular variant is not correct. This variant often displays extracapillary hypercellularity caused by podocyte hyperplasia.

References

1Das P, Sharma A, Gupta R, Agarwal SK, Bagga A, Dinda AK. Histomorphological clas­sification of focal segmental glomeruloscle-rosis: A critical evaluation of clinical, histo-logic and morphometric features. Saudi J Kidney Dis Transpl 2012;23:1008-16.
2D'Agati V, Fogo AB, Bruijin JA, Jennette JC. Pathologic classification of focal segmental glomerulosclerosis: A working proposal. Am J Kidney Dis 2004;43:368-82.
3Deegens JK, Steenbergen EJ, Borm EF, Wetzels JF. Pathological variants of focal segmental glomerulosclerosis in an adult Dutch population-epidemiology and outcome. Nephrol Dial Transplant 2008;23:186-92.
4Nada R, Kharbanda JK, Bhatti A, Minz RW, Sakhuja V, Joshi K. Primary focal segmental glomerulosclerosis in adults: Is the Indian cohort different? Nephrol Dial Transplant 2009;24:3701-7.
5Thomas DB, Franceschini N, Hogan SL, et al. Clinical and pathologic characteristics of focal segmental glomerulosclerosis pathologic variants. Kidney Int 2006;69:920-6.
6Testagrossa LA, Malheiros DM. Study of the morphologic variants of focal segmental glomerulosclerosis: A Brazilian report. J Bras Pathol Med Lab 2012;48:211-5.
7Shakeel S, Mubarak M, Kazi JI, Jafary N, Ahmed E. Frequency and clinicopathological characteristics of variants of primary focal segmental glomerulosclerosis in adults presenting with nephrotic syndrome. J Nephropathol 2013;2:28-35.