IS Case 125: Renal Papillary Necrosis
Imaging Sciences URMC 2008
Publication Date: 2009-05-20
History
Patient is a 16-year-old male with hemoglobin SS disease and history of cerebrovascular attack who was admitted for gross hematuria.
Findings
Contrast-enhanced excretory phase CT images show clefts or cavities filled with urine and contrast material extending from fornices to pyramid tips.
Diagnosis
Renal Papillary Necrosis
Discussion
Ischemic necrosis of the renal papilla has many causes including diabetes mellitus, pyelonephritis, obstructive uropathy, sickle cell disease, tuberculosis, trauma, cirrhosis, coagulopathy, analgesic nephropathy and renal vein thrombosis. Patients can present with flank pain, dysuria, fever, chills, ureteral colic, acute oliguric renal failure, hypertension, proteinuria, pyuria, hematuria and leukocytosis.
In the past, renal papillary necrosis has been diagnosed mostly with intravenous urography. It is seen when contrast material in the collecting system fills a necrotic cavity centrally or peripherally in the papillae.
Contrast–enhanced CT during the excretory phase can also demonstrate necrosis. Ischemia evolving into renal papillary necrosis is best seen on the nephrographic phase of CT scan with small, ill-defined regions of decreased contrast enhancement at the tip of the medullary pyramid.
During excretory phase of CT, contrast material within the collecting system can delineate necrotic cavities or clefts in the papillae. Sloughed papilla can be seen as filling defects within calyces. Sloughed tissue may obstruct the ureter. If a necrotic papilla does not detach from the pyramid, it can calcify and form small stones.
In healing, the papilla can epithelialize with resultant blunting of its tip. Reduction in kidney size can result from thinning of the parenchyma.
When cavities are present, differential diagnosis of renal papillary necrosis includes cystic lesions, hydronephrosis, congenital megacalices, parapelvic cysts and caliceal diverticula.
References
- Dähnert, W (ed.). Radiology Review Manual, 6th ed. New York:Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.
- Jung DC, Kim SH, Jung SI, Hwang SI, Kim SH. Renal papillary necrosis: review and comparison of findings at multi-detector row CT and intravenous urography. Radiographics. 2006 Nov-Dec;26(6):1827-36. [PMID: 17102053]
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