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Histological Subtypes & Staging of Post-Chemotherapy Wilms Tumor According to SIOP 2001 Protocol: Study at the Children’s Hospital, Lahore

Introduction: Pediatric renal tumors constitute 7 to 8% of pediatric solid malignancies and most common is Wilms tumor. It usually presents as unilateral mass with sporadic and familial associations. It is currently treated by NWTS and SIOP protocols worldwide. In our hospital setup we follow SIOP 2001 protocol to subcategorize different histological subtypes and staging of Wilms tumor after completing four cycles of chemotherapy.
Aims & Objectives: To determine the frequency of histological subtypes of Wilms tumor (WT) in post chemotherapy nephrectomy specimens
Place and duration of study: Histopathology Section of Pathology Department, Children’s Hospital and Institute of Child Health Lahore from January 2015 to June 2018.
Material & Methods: Ninety-three radical nephrectomy specimens of different histological subtypes i.e. Wilms Tumor (WT) consisting of blastemal predominant (BP), epithelial predominant (EP), stromal (ST), mixed (MT), regressive (RP), completely necrotic (CN) and diffuse anaplastic (DA) were analyzed. Risk categorization and staging proposed by SIOP 2001 was appraised. Data analysis was done using SPSS version 23.
Results: A total of 93 cases were included in the present study. Mean age of children recorded was 42 months with male predominance. Mean tumor size after chemotherapy was 7.25 cm. Majority cases were observed on the right side. Regarding the histological subtype there was a predominant group of MT while least observed was DA. Based on subtypes and necrosis, majority of WT were of intermediate risk (IR) and stage I tumors.
Conclusion: Majority of pretreated cases (n=80, 85.1%) were stage 1 tumors. Commonest histological subtype is MT followed by RP, CN, EP, BP, ST and DA.