Wilms tumourlet (nephroblastoma) occurring in an end stage kidney

Abstract

Adult nephroblastoma is an uncommon lesion with 167 cases reported to 1980. The vast majority of cases present with a renal mass. There are only very few reported cases of incidental finding of nephroblastoma or tumourlets when the kidney Is removed for nonneoplastic pathology. In our case a 39 year old male presented with pelvi-ureteric obstruction for which end-stage kidney nephrectomy was performed. The kidney showed fibrotic cortex and medulla with a cystically dilated collecting system. On the anterior surface of the kidney Immediately beneath the cortex was a 4x3x2mm dense white nodule. Histologically lesion was composed predominantly of renal blastema with occasional tubular formation at the edges of the lesion. The surrounding renal parenelyma showed the changes of chronic pyelonephritis and end-stage kidney. The features of the main lesion are those of a Wilm’s tumourlet. Immunohistochemistry was performed and showed the lesion was positive for AE1/AE3 and Cam 5.2 but negative for vimentin, S100 and CEA, Though Wilm’s tumourlets have been described previously in association with nephroblastoma, we can find no record of an association with end-stage kidney.