DDX of cystic renal mass

Approach to the DDX of cystic renal mass:

  • US is the first step in imaging
  • The most likely cause of a cystic renal mass is a congenital anomaly of renal formation
  • In the clinical setting of infection, strongly consider the diagnosis of renal abscess. If this diagnosis is made, repeat the US in a month to ensure the abscess has resolved
  • Otherwise you must move on to CT or MR and begin the workup for malignancy