Radiography
Excretory urography in a patient with diabetes. A film obtained at 5 minutes shows horns from the calices, ring shadows, and an egg-in-a-cup appearance (ring sign) characteristic of renal papillary necrosis.
Excretory urography in a 53-year-old man with analgesic-induced nephropathy. A film obtained at 15 minutes after administration of contrast shows a wavy renal outline with tracks of contrast extending from fornix, ring shadows caused by the sloughing of papillae, and an egg-in-a-cup appearance characteristic of renal papillary necrosis. Note the bamboo spine, characteristic of ankylosing spondylitis.
Nephrotomogram in a 53-year-old man with analgesic-induced nephropathy (same patient as above) clearly demonstrates a wavy contour of the renal outline (ie, renal scars with focal atrophy).
Excretory urography in a patient with renal papillary necrosis and pyeloureteritis cystica. Note the bilateral loss of the renal mantle with contrast tracking from the renal fornix in the lower pole of the right kidney. Note also the multiple smooth filling defects in the ureter, caused by ureteritis cystica.
Findings
Techniques and findings
- Plain radiograph findings
- The kidneys are normal in size and contour except in the late stage of disease, during which they shrink and demonstrate a wavy contour as a result of the prominence of the septal cortex around the atrophied centrilobular cortex.
- Sloughed papillae may calcify; they may be observed as curvilinear or ringlike calcification measuring up to 5-6 mm in diameter. The appearance of calcification implies that a change in urine bacteriology has occurred such that Proteus organisms predominate.
- Tiny calcifications may be observed in the region of the liver, spleen, adrenal glands, and lymph nodes in patients with abdominal tuberculosis.
- Excretory urography findings (see Images above)
- Urographic findings depend on the stage of the disease.
- The kidneys are of normal size, and the contour is smooth until the late stage, in which the kidneys shrink and demonstrate a wavy contour.
- In the early stage, papillary swelling may be the only abnormal finding; papillary necrosis may be difficult to diagnose.
- Later, necrosis of the papillae, in association with disruption of the urothelial lining, causes tracking of contrast from the fornix parallel to the long axis of the papillae. These developments may produce the lobster claw sign. Cavitation of renal papillae then occurs; such cavitation may be incomplete (medullary) or complete (papillary) and may be either central or eccentric.
- Shrinkage and sloughing of the necrotic papillae cause forniceal widening and calyceal clubbing.
- Sloughed papillae cause a filling defect in the pelvocalyceal system and in the ureter.
- Retrograde pyeloureterography findings
- Findings are similar to those of excretory urography.
- Minor abnormal papillary findings may be demonstrated readily when urographic findings are indeterminate.
Calcification in a sloughed papilla is characteristically ring shaped and may be the only abnormal radiologic finding in cases of necrosis in situ. Calcification is common in patients with analgesic-induced papillary necrosis; it has not been reported in patients who have papillary necrosis associated with hemoglobinopathy.
Persistent streaking of contrast from the polar fornix is almost diagnostic of renal papillary necrosis. Necrosis in situ is difficult to diagnose because necrotic tissue does not slough. Filling defects within the pelvocalyceal system and the ureter are nonspecific findings. Opacification of the collecting system is poor when renal function is impaired.
Medullary calcification may occur in patients with hyperparathyroidism, renal tubular acidosis, and medullary sponge kidney, as well as patients with hypercalcemia. The presence of ringlike calcifications of up to 5-6 mm in diameter is characteristic of sloughed papillae.
Findings of medullary calcification (nephrocalcinosis) are nonspecific. Calcification may be the only abnormal radiologic finding in papillary necrosis in situ.
Imaging pearls
- Retrograde pyelography is sensitive, especially in the presence of renal impairment or for patients in whom urographic findings are inconclusive. The procedure cannot help in the assessment of renal function or the renal parenchyma.
- In the early stage, when papillary swelling may be the only abnormal radiologic finding, swelling is difficult to recognize. Necrosis in situ cannot be diagnosed unless calcification has occurred.
- Pyelosinus extravasation, which may occur with forceful injection of a large volume of contrast, may mimic the tracking of contrast from the fornix in papillary necrosis.
- Inadvertent injection of air bubbles may produce filling defects, but the defects appear smooth and rounded and therefore may be differentiated from the irregular filling defects found in sloughed papillae.
Computed Tomography
Findings
Techniques and findings
CT does not offer much help in the diagnosis of renal papillary necrosis, but reformatted multidetector images may change the role of CT.7,10,11,12,13
- CT is sensitive in detecting calcifications.
- CT may demonstrate multiple bilateral ring shadows in the medulla, some of which are triangular.
- Contrast may fill the clefts in the renal parenchyma.
- CT may be helpful in evaluating the nature of the material (sloughed papillae)14 that causes the filling defect within the collecting system.
- Findings of a medullary cavity and calcification are nonspecific.
Imaging pearls
- CT findings are not diagnostic, but the scans may be useful for patients with poor renal function in whom intravenous pyelogram findings are not helpful.
- Iodinated contrast agents should be used cautiously in patients with compromised renal function.
Magnetic Resonance Imaging
Findings
Techniques and findings
MRI has no specific role in the management of papillary necrosis; however, it may provide a useful alternative to iodinated contrast for patients with depressed renal function and for those who are allergic to iodinated contrast medium.5,6
Accuracy
There is insufficient experience with MRI in the diagnosis of papillary necrosis to draw conclusions about its reliability.
The rates of false-positive and false-negative diagnoses of renal papillary necrosis with the use of MRI have not yet been determined.
Ultrasonography
Findings
Techniques and findings
- Sonographically, areas of cavitation in the papillae may appear as multiple rounded or triangular cystic spaces in the medulla arranged around a renal sinus echo, demonstrating a garland pattern.
- Occasionally, bright echoes produced by arcuate arteries may be visualized at the periphery of the cystic space.
- Sloughed papillae may appear echogenic and cast shadows when calcified.
- The collecting system may be dilated when obstructed by sloughed papillae.
- A hyperechoic medulla may be observed in patients with hyperparathyroidism and medullary sponge kidney and in patients with conditions that cause hypokalemia or hypercalcemia.
Accuracy
- Sonographic findings are nonspecific for patients with renal papillary necrosis.
Nuclear Imaging
Findings
No role exists for isotope studies in the diagnosis of renal papillary necrosis; however, such studies are useful in evaluating renal function.
More on Papillary Necrosis |
| Overview: Papillary Necrosis |
 Imaging: Papillary Necrosis |
| Follow-up: Papillary Necrosis |
| Multimedia: Papillary Necrosis |
| References |
| Further Reading |
| « Previous Page | Next Page » |
References
Gonwa TA, Hamilton RW, Buckalew VM Jr. Chronic renal failure and end-stage renal disease in northwest North Carolina. Importance of analgesic-associated nephropathy. Arch Intern Med. Mar 1981;141(4):462-5. [Medline].
De Broe ME, Elseviers MM. Analgesic nephropathy. N Engl J Med. Feb 12 1998;338(7):446-52. [Medline].
Henrich WL. Analgesic nephropathy. Trans Am Clin Climatol Assoc. 1998;109:147-58; discussion 158-9. [Medline].
Kovacevic L, Bernstein J, Valentini RP, et al. Renal papillary necrosis induced by naproxen. Pediatr Nephrol. Aug 2003;18(8):826-9. [Medline].
Pedrosa I, Chou MT, Ngo L, H Baroni R, Genega EM, Galaburda L, et al. MR classification of renal masses with pathologic correlation. Eur Radiol. Feb 2008;18(2):365-75. [Medline].
Pedrosa I, Sun MR, Spencer M, Genega EM, Olumi AF, Dewolf WC, et al. MR imaging of renal masses: correlation with findings at surgery and pathologic analysis. Radiographics. Jul-Aug 2008;28(4):985-1003. [Medline].
Craig WD, Wagner BJ, Travis MD. Pyelonephritis: radiologic-pathologic review. Radiographics. Jan-Feb 2008;28(1):255-77; quiz 327-8. [Medline].
Prasad SR, Narra VR, Shah R, Humphrey PA, Jagirdar J, Catena JR, et al. Segmental disorders of the nephron: histopathological and imaging perspective. Br J Radiol. Aug 2007;80(956):593-602. [Medline].
Vijayaraghavan SB, Kandasamy SV, Mylsamy A, Prabhakar M. Sonographic features of necrosed renal papillae causing hydronephrosis. J Ultrasound Med. Sep 2003;22(9):951-6; quiz 957-8. [Medline].
Hill SC, Hoeg JM, Avila NA. Nephrocalcinosis in homozygous familial hypercholesterolemia: ultrasound and CT findings. J Comput Assist Tomogr. Jan-Feb 1991;15(1):101-3. [Medline].
Saifuddin A, Bark M. Case report: computed tomography demonstration of renal papillary necrosis. Clin Radiol. Oct 1991;44(4):275-6. [Medline].
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. Nov-Dec 2006;26(6):1827-36. [Medline].
Henrich WL, Clark RL, Kelly JP, Buckalew VM, Fenves A, Finn WF, et al. Non-contrast-enhanced computerized tomography and analgesic-related kidney disease: report of the national analgesic nephropathy study. J Am Soc Nephrol. May 2006;17(5):1472-80. [Medline].
Gordon M, Cervellione RM, Postlethwaite R, Shabani A, Hennayake S. Acute renal papillary necrosis with complete bilateral ureteral obstruction in a child. Urology. Mar 2007;69(3):575.e11-2. [Medline].
Chitale SV, Sams VR, Burgess NA. Pericalyceal haemangioma and papillary necrosis. J R Soc Med. Sep 2000;93(9):482-3. [Medline].
Laissy JP, Abecidan E, Karila-Cohen P, et al. [IVU: a test of the past without future?]. Prog Urol. Jun 2001;11(3):552-61. [Medline].
Further Reading
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Papillary Necrosis (Urology)
Renal Failure, Acute
Anemia, Acute
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Keywords
papillary necrosis, renal medullary necrosis, necrotizing papillitis, renal papillary necrosis, localized papillary necrosis, diffuse papillary necrosis, unilateral papillary necrosis, bilateral papillary necrosis, renal dysfunction, renal failure, anemia, uremia
