Perirenal cobwebs are the presence of prominent perinephric septa. It is best appreciated on CT images.
The cobweb is considered to be due to engorged venous collaterals or due to oedema and fluid extravasation into the perirenal space 1.
Perirenal cobwebs may be seen in many benign and malignant conditions of the kidney. The commonest cause is acute ureteral obstruction due to a stone. It may also be seen in other situations such as
- 1. Dyer RB, Chen MY, Zagoria RJ. Classic signs in uroradiology. Radiographics. 2004;24 Suppl 1 (suppl 1): S247-80. Radiographics (full text) - doi:10.1148/rg.24si045509 - Pubmed citation
- 2. Lien HH, Lund G, Talle K. Collateral veins in left renal vein stenosis demonstrated via CT. Eur J Radiol. 1983;3 (1): 29-32. Pubmed citation