This study describes neoplastic and non-neoplastic entities involving the perinephric space and describes and their key imaging characteristics, often allowing to narrow the likely diagnosis.
• Despite often a bulky disease, perinephric lymphoma does not produce obstruction or stenosis.
• In primarily fatty masses, defects within the renal capsule likely represent angiomyolipoma.
• Consider paraganglioma if biopsy is planned; biopsy may lead to catecholamine crisis.
The perinephric space, shaped as an inverted cone, sits between the anterior and posterior renal fasciae. It can play host to a variety of clinical conditions encountered daily in the reporting schedule for a radiologist. Lesions may be classified and diagnosed based on their imaging characteristics, location and distribution. A broad range of differential diagnoses can be attributed to pathology sitting within this space, often without clinical signs or symptoms. An understanding of commonly encountered conditions affecting the perinephric space, along with characteristic imaging findings, can illustrate and often narrow the likely diagnosis. The aim of this essay is to describe commonly encountered neoplastic and non-neoplastic entities involving the perinephric space and to describe their key imaging characteristics.