Which imaging feature is associated with papillary necrosis?

Which imaging feature is associated with papillary necrosis?

• A. Sloughed papilla in urine
• B. Triangular cystic areas in the cortex
• C. Echogenic material and calcifications within the collecting system (sloughed papilla)
• D. Accumulation of fat in the renal sinus

Answer: (C)

Papillary necrosis involves degeneration and sloughing of the renal papilla into the collecting system. On imaging, the hallmark is echogenic material within the collecting system, often with calcifications, representing a sloughed papilla. This is why the imaging feature described as echogenic material and calcifications within the collecting system best fits papillary necrosis. A sloughed papilla in urine can occur, but the key imaging finding is within the collecting system. Triangular cystic areas in the cortex point to cortical infarcts or chronic pyelonephritis rather than papillary necrosis, and accumulation of fat in the renal sinus indicates renal sinus lipomatosis, not papillary necrosis.

Papillary necrosis involves degeneration and sloughing of the renal papilla into the collecting system. On imaging, the hallmark is echogenic material within the collecting system, often with calcifications, representing a sloughed papilla. This is why the imaging feature described as echogenic material and calcifications within the collecting system best fits papillary necrosis. A sloughed papilla in urine can occur, but the key imaging finding is within the collecting system. Triangular cystic areas in the cortex point to cortical infarcts or chronic pyelonephritis rather than papillary necrosis, and accumulation of fat in the renal sinus indicates renal sinus lipomatosis, not papillary necrosis.