A pelvic mass 21 years after a Wilms tumour: late recurrence or new tumour?

We retrace and analyse the diagnostic and therapeutic path of the case that represents a mixture of two different conditions which might be unrelated or intertwined in a causal relationship. Among the differential diagnosis of a prostatic mass, the possibility of a prostatic sarcoma should not be overlooked, in presence of blastemic elements, even in a patient with a WT history.