Aggressive non-Hodgkin's lymphoma mimicking unilateral transitional cell carcinoma of renal pelvis. The risk of making a diagnostic mistake.

A 78-year-old Caucasian man was referred to our department because of an incidental unilateral mass involving the right renal sinus. As the patient showed no urological disease at flexible ureterorenoscopy, a subsequent percutaneous CT-targeted biopsy was mandatory, confirming an aggressive non-Hodgkin disease involving the renal pelvis that is, to the best of our knowledge, the second reported case in literature. A whole body FDG-PET excluded multiple expression of this disease, and the patient underwent a chemotherapeutic scheme resulting in a stable marked reduction in tumor volume. To the date, the available experience on the management and outcome of such cases is extremely lean. In this scenario, our case can contribute to shorten the time-to-diagnosis by reporting a complete images overview comprising abdominal CT scan, MRI and FDG-PET-CT, hence making this clinical entity easier presumable in clinical daily practice and offering a possible suggestion for an effective treatment.