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

Introduction: Late Wilms tumour (WT) recurrences are rare events with poorly understood pathogenesis. They could be induced by previous chemo- and radiotherapy regimens, which can also prompt a rhabdomyomatous differentiation. Prostatic embryonal rhabdomyosarcoma (PER) is an extremely rare disease in adults, with an aggressive behaviour and abysmal prognosis. Radio-induced PER have been described. Case description: We report the case of a 29 years old man, with a history of WT, diagnosed with a symptomatic prostatic mass. Blastemic elements were shown at the transrectal biopsy, suggesting the possibility of a late WT recurrence. After laparoscopic resection, an unexpected pathologic diagnosis was reached: PER. Conclusion: 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.