Spectrum of pediatric kidney tumours with special references to WT1 immunostain at a tertiary care hospital

Context or Background: Pediatric renal tumours are the second most common solid tumours in children. The most common in this group is Wilms tumour with mesoblastic nephroma being the 2 nd most common tumour in children, younger than 3 months. Aims and Objectives: The present study was conducted to study the epidemiological occurrence of pediatric renal tumours at a tertiary care hospital and to study the diagnostic efficacy of WT1 immunostaining in distinguishing Wilms tumour from other types of renal tumours. Materials and Methods: It was a single institution-based prospective and observational study conducted for 2 years (from October 2013 to September 2015) in the department of pathology in our hospital. A total of 50 cases were enrolled in this study all were below 15 years of age. Results: Nephroblastoma or Wilms tumour was found to be the most common type, occurring in 66% cases. Fourteen out of 33 cases of Wilms tumour showed triphasic components (blastemal, epithelial, and stromal) with Blastemal type Wilms being the second most common (11 cases). WT1 immunostaining was positive in 93.9% cases of nephroblastoma. The highest amount of nuclear positivity noted in blastemal cells followed by epithelial cells. Rhabdomyoblastic differentiation and regressive variant showed nonspecific cytoplasmic staining. Cystic partially differentiated nephroblastoma and diffuse anaplasia type Wilms tumour showed nuclear staining in blastemal cells. Conclusion: The expression of WT1 immunostain was found to be diagnostically significant in differentiating Wilms tumour from other renal tumours.