Wilms' Tumour in an Adult- A Case Report of an Unusual Lesion.

Wilms' tumour, a renal malignancy, primarily occurs in children with a peak incidence between 2 to 5 years age group and accounts for approximately 95% of childhood renal malignancies. Though rarely, it may also occur in adults with an incidence rate of less than 0.2 per million per year. Microscopically, there is no difference between Wilms' tumour of paediatric and adult age groups. But the prognosis for adults with Wilms' tumour is thought to be worse than that for children possibly due to more aggressive clinical course in case of adult Wilms' tumour. They are often associated with higher tumour stage at the time of presentation and outcome is often worse than paediatric age group possibly due to difficulty in diagnosis, inappropriate staging, and lack of standard treatment protocol. We report a case of 28-year-old lady presented with flank pain and abdominal lump. Abdominal CT scan showed a right renal mass suggestive of malignancy. A provisional diagnosis of renal cell carcinoma was made based on clinical and radiological findings. Nephrectomy was performed and a final morphological diagnosis of Wilms' tumour was given. Immunohistochemical study showed strong Wilms' Tumour 1(WT1) positivity in both blastemal and epithelial components confirming the morphological diagnosis. In view of its diagnostic difficulty and rare occurrence in adults, this case is being reported.