Extrarenal

Extrarenal is a medical term describing tissues, structures, or processes located outside the kidney. The word combines the prefix extra- (outside) with renal (relating to the kidney). It is used in anatomy, radiology, and pathology to convey that something originates or resides outside the renal parenchyma, even when in proximity to the kidney or within the retroperitoneal space.

In anatomical terminology, extrarenal variants concern parts of the renal collecting system that lie outside the renal parenchyma. The extrarenal pelvis, for example, refers to a collecting-system configuration where portions of the renal pelvis lie outside the kidney itself. Such variants may be incidental findings on imaging and can be associated with urinary tract dynamics such as hydronephrosis or obstruction, though they often require no treatment unless symptoms or complications arise.

In radiology and pathology, extrarenal is also used to describe masses, cysts, or lesions that arise outside the kidney but are located near it. Distinguishing extrarenal from intrarenal (originating within the kidney) processes is important for diagnosis, surgical planning, and prognosis. Imaging modalities such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) are commonly employed to assess the relationship of a lesion to the renal parenchyma and collecting system.

See also: ectopic kidney, renal pelvis, hydronephrosis.