Comment on "Ten-year experience of pediatric renal biopsies from a single center in Pakistan".

Sir,

I have read with interest the article by Absar et al. published in your esteemed journal.[1] Although it provides information on the pattern of biopsy-proven renal disease (BPRD) in children from Pakistan, there are many points which need correction, as mentioned below: The authors claim that this is the first study from Pakistan, which is incorrect. We have earlier reported on both the overall pattern of BPRD in 801 children and the pattern of histopathology underlying 538 cases of childhood idiopathic nephrotic syndrome (INS).[23] Moreover, all our biopsies were fully worked up, including examination by light microscopy (LM), immunoflourescence (IF), and electron microscopy (EM), in contrast to the subject study, which is based on LM and IF only. A few other single-center, LM-based studies are also available in the literature from Pakistan.[4] It is worth mentioning here that we provide all our services free of cost and our catchment area extends, more or less, to the entire country.[5] Thus, we believe that, our studies are more truly representative of the pattern of BPRD in children from Pakistan and may serve as the foundation for future establishment of the national renal biopsy registry.

The overall pattern of BPRD in the study by Absar et al. is more or less similar to our finding,[23] except for the markedly low prevalence of focal segmental glomerulosclerosis (FSGS), which is surprising, given the very high prevalence of steroid-resistant NS (SRNS) in their study. It is very likely that the lesion of FSGS may have been overlooked in the biopsies. This lesion is notorious for being easily missed, especially if not looked for, vigilantly and by examining multiple serial sections and tinctorial stains, especially during the early stage of disease.[6] In the above study, a very important stain, i.e., silver stain, has also not been used for the LM study.

The incidence of SRNS in children in the literature varies from 10% to 20%,[7] and we found SRNS in about 30% of our 538 children,[3] but the frequency of SRNS in the above study is much higher (twice the number of steroid dependant NS) and needs explanation. These biopsy indications for subsets of NS are not compatible with the histopathological diagnoses provided, as alluded to, earlier. The definition of SRNS provided is also incorrect.[1] The reference quoted is of revised guidelines from the Indian Pediatric Nephrology group.[8] The correct definition mentioned in the guidelines is “absence of remission despite therapy with daily prednisolone at a dose of 2 mg/kg per day for four weeks.”[8]

It is not clear whether the age given in the results is the age at the time of presentation or biopsy. CNS is not a pathological diagnosis but a clinical term used for INS with onset at birth or within 3 months of life. There is no mention of the histopathological lesions in the two cases of CNS.

Recommendations of the authors for lowering the threshold for biopsying children with renal diseases are not substantiated by the data. I hope the above points will help in better understanding the pattern of BPRD in the pediatric population in Pakistan and the region.