Paediatric renal tumors: An insight into molecular characteristics, histomorphology and syndromic association

Paediatric renal tumors are rare and accounts for about 7% of all paediatric malignant tumors. The spectrum of paediatric renal tumors ranges from benign to malignant. Benign tumors include cystic nephroma, metanephric tumors and ossifying renal tumor of infancy. Tumor with low grade malignancy includes mesoblastic nephroma. Malignant tumors are nephroblastoma, clear cell sarcoma, malignant rhabdoid tumor, anaplastic sarcoma and Ewing sarcoma. Additionally, there are molecularly defined renal tumors, which includes renal cell carcinoma (RCC) with MiT translocations, ALK-rearranged RCC, eosinophilic solid and cystic RCC and SMARCB1- deficient renal medullary carcinoma. These tumors apart from having characteristic clinical presentation and histomorphology, also carry typical molecular mutations and translocations. Certain renal tumors have association with various genetic syndromes such as Beckwith-Weidmann syndrome, Wilm's tumor, aniridia, genitourinary anomalies and mental retardation syndrome, Denys-Drash syndrome, rhabdoid tumor predisposition syndrome and DICER syndrome. This review article focusses on molecular characteristics, histomorphology and syndromic association of pediatric renal tumors, their immunohistochemical approach to diagnosis with recent updates in molecularly defined renal tumors.