Familial Metachronous Wilms' Tumour in a Sibling with Previous Bilateral Synchronous Wilms' Tumour: A Rare Familial Cluster

Abstract Wilms Tumour (WT) is the most common renal malignancy of childhood, typically occurring sporadically. Familial WT accounts for fewer than 2% of cases and often involves germline predisposition syndromes. Metachronous WT in siblings - particularly when one sibling previously presented with bilateral synchronous disease - is exceptionally rare. We report a case of a child presenting with unilateral WT whose older sibling had been treated several years earlier for bilateral synchronous WT. This case highlights the importance of familial risk assessment, genetic counselling, structured surveillance, and early detection strategies in families with suspected hereditary WT predisposition.