Golf-ball-on-a-tee sign | Radiology Signs

Answer:
The golf ball–on-tee sign is caused by renal papillary necrosis, a condition where the renal papilla undergoes central necrosis and sloughing. This necrotic cavity within the papilla fills with contrast material during excretory urography, creating the appearance of a “golf ball” adjacent to a blunted calyx, which forms the “tee.” This sign indicates necrosis of the renal papilla and is associated with clinical conditions such as diabetes mellitus, analgesic (especially phenacetin and aspirin) nephropathy, sickle cell hemoglobinopathies, nonsteroidal anti-inflammatory drug (NSAID) use, and infections including tuberculosis and severe pyelonephritis.

Why is it called so?

It is named the “golf ball–on-tee” sign because the contrast-filled necrotic papillary cavity resembles a golf ball resting on a tee-shaped blunted calyx on imaging. The blunted calyx forms the base (tee), and the round cavity filled with contrast represents the golf ball.

Pathophysiology

The collecting tubules within the medullary pyramid converge into papillary ducts that open at the papillary tip into the calyx. In papillary necrosis, ischemic or toxic injury causes central necrosis of the papilla, leading to sloughing and formation of an excavated cavity. This cavity fills with contrast during excretory urography and communicates with the partially destroyed calyceal concavity, resulting in the characteristic imaging appearance. The necrosis reflects impaired blood flow or direct toxic/infectious destruction affecting the vulnerable central papillary tissue.

Alternative names:
Also referred to as the ball-on-tee sign or egg-in-cup appearance.

Other associated named signs:
No specific associated signs are typically named alongside this; however, papillary necrosis may present with other urographic signs depending on the stage and severity.