[Retroperitoneal mass: a clinical case]. / Formazione retroperitonale: caso clinico.

The Authors discuss about a case of retroperitoneal mass, recently observed in their Institution. About the nature of the mass, by the imaging and clinical evolution, the Authors suppose a traumatic genesis: subcapsular renal hematoma, occurred 2 years before, broken and expanded in retroperitoneal space and then superficialized in the left lumbar region.