A 3-year-old child presented with hypoechoic lesion on USG abdomen. Most probable diagnosis:

Ans: c (Wilms tumour) Ref: Nelson, 17th ed, p. 1711 & OP Ghai, 6th ed, p. 574Commonest abdominal malignancy in children in the above age group is Wilms tumour; eventhough the commonest malignancy is neuroblastoma. Most of the patients with wilms tumour present as asymptomatic abdominal mass.Wilms tumour* Also called nephroblastoma* Most common cancer of kidney in children* Second most common abdominal malignancy in children (neuroblastoma is the most common abdominal malignancy)* Most important prognostic factor is its histologic type* It is a complex mixed embryonal neoplasm of kidney composed of 3 elements-- blastema, epithelia, stroma* Usual ly occurs between 2-5 years of age* Incidence of bilateral Wilms is 7%* Chromosomal anomaly associated with wilms tumor is deletion of chromosome 11 p 13 (WT1 gene)Histologically divided into 2 types:* Favourable histology* Unfavourable histologyUnfavorable has 3 sub types:* Anaplastic* Clear cell -- commonly metastasise to bone* Rhabdoid -- commonly metastasise to brain