Dilated Renal Calices



Dilated Renal Calices


Michael P. Federle, MD, FACR



DIFFERENTIAL DIAGNOSIS


Common



  • Ureteral Obstruction



    • Ureteral Stone


    • Transitional Cell Carcinoma


    • Periureteral Metastases o Retroperitoneal Fibrosis


    • Primary Pelvic Malignancy



      • Prostate Carcinoma


      • Rectal Carcinoma


      • Cervical & Endometrial Carcinoma


  • Ureterectasis of Pregnancy


  • Ureteral Duplication


  • Distended Urinary Bladder


  • Overhydration, Diuresis


  • Vesicoureteral Reflux


  • Prominent Extrarenal Pelvis (Mimic)


  • Renal Sinus (Peripelvic) Cysts (Mimic)


  • Renal Sinus Blood Vessels (Mimic)


  • Ureteropelvic Junction Obstruction


  • Pyonephrosis


Less Common



  • Renal Papillary Necrosis


  • Renal Tuberculosis


  • Pyelonephritis, Xanthogranulomatous


  • Megacalices, Megaureter


  • Caliceal Diverticulum


  • Renal Cysts (Mimic)


  • AD Polycystic Disease, Kidney


  • Renal Metastases and Lymphoma


  • Blood-Filled Renal Pelvis


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Determine if all calices are dilated & in communication with a dilated renal pelvis & ureter


  • CT & MR are complementary to US



    • Include pyelographic (delayed) phase enhanced images


Helpful Clues for Common Diagnoses



  • Ureteral Obstruction



    • Most common cause with several specific etiologies (calculi, tumor, etc.)


    • CT and MR better than US at showing the etiology of the ureteral obstruction


    • Ureteral Stone



      • Dilated ureter ends at high density intraluminal focus


    • Transitional Cell Carcinoma



      • Small soft tissue density mass within the lumen or wall of the ureter


      • May see “goblet sign”; dilation of the ureteral lumen proximal and distal to obstructing tumor


    • Retroperitoneal Fibrosis



      • Encases and obstructs ureters through lumbar region


      • Mantle of soft tissue surrounds aorta and IVC


      • Retroperitoneal nodal metastases may have a similar appearance and may rarely cause ureteral obstruction


    • Primary Pelvic Malignancy



      • Dilated ureter ends in a soft tissue density mass or retroperitoneal nodes that encase the ureter


  • Ureterectasis of Pregnancy



    • Due to hormonal influence plus mass effect of gravid uterus


    • Affects right kidney more than left


    • May persist after pregnancy


    • Rarely associated with rupture of the collecting system (usually with an underlying renal disease, such as infection)


  • Ureteral Duplication



    • Upper pole ureter is more often ectopic in insertion and dilated


    • Look for 2 ureters on one side; upper pole ureter will have delayed concentration & excretion of contrast medium if it is obstructed


    • Either ureter can be obstructed by calculi and other etiologies


  • Distended Urinary Bladder



    • May cause back pressure and dilation of ureters and calices


    • Re-image after emptying bladder



      • Should return to normal caliber


  • Vesicoureteral Reflux



    • Acute or chronic dilation of ureter and calices; scarred parenchyma


  • Prominent Extrarenal Pelvis (Mimic)



    • Calices and ureter not dilated


    • Common and asymptomatic


  • Renal Sinus (Peripelvic) Cysts (Mimic)



    • Coronal view (US) shows lack of communication of cysts with renal pelvis and proximal ureter



    • Delayed imaging on CECT often necessary to distinguish renal sinus cysts from hydronephrosis



      • Contrast-opacified urine distinguished from the water density peripelvic cysts


      • Coronal reformations are also helpful


  • Renal Sinus Blood Vessels (Mimic)



    • Sonolucent, but show flow on Doppler


    • May also be a mimic of hydronephrosis on “black blood” MR image sequences



      • Usually not a problem on CT


      • Even on NECT, blood vessels are different attenuation than calices


  • Ureteropelvic Junction Obstruction



    • Relatively common congenital narrowing at the UPJ that often results in striking dilation of the pelvis & calices, especially with a fluid or diuretic challenge


    • May be due to a crossing vessel that compresses the UPJ


  • Pyonephrosis



    • Hydronephrosis plus infected urine = urgent need for drainage


    • Fluid may be higher than water density on CT; diffusely mildly echogenic


    • Consider pelvic inflammatory conditions that may involve the ureter (e.g., diverticulitis, Crohn disease, gynecologic infections)


Helpful Clues for Less Common Diagnoses



  • Renal Papillary Necrosis



    • Calices may appear blunted and dilated due to sloughed papillae


  • Renal Tuberculosis



    • May cause stricture of infundibula and focal hydronephrosis


    • Caseous infection of parenchyma may mimic caliectasis


  • Pyelonephritis, Xanthogranulomatous



    • Underlying calculi may cause hydro- or pyonephrosis


    • Xanthomatous replacement of parenchyma may be low density, mimicking caliectasis


  • Megacalices, Megaureter



    • Rare congenital anomalies


    • Renal function may remain normal


  • Caliceal Diverticulum



    • Outpouching from a calyx may simulate focal caliectasis


  • Renal Cysts (Mimic)



    • Multiple simple cysts or polycystic disease


    • If numerous, may simulate dilated calices


    • Usually spherical


  • Renal Metastases and Lymphoma



    • TCC, metastases, lymphoma may infiltrate pelvis; cause or simulate hydronephrosis


    • Lymphoma is especially likely to be homogeneous and hypodense (CT), and sonolucent (US)


  • Blood-Filled Renal Pelvis



    • Trauma or coagulopathic hemorrhage may distend renal pelvis and calices with blood






Image Gallery









Axial CECT shows left-sided hydronephrosis, renal enlargement, and perinephric stranding, due to a distal ureteral stone.






Axial NECT shows right-sided hydronephrosis and extensive infiltration of the perirenal space, due to forniceal rupture, caused by a small stone at the ureterovesical junction.







(Left) Axial CECT shows dilated renal pelvis & calices in the right kidney, due to a transitional cell carcinoma of the distal ureter. (Right) Axial CECT shows a soft tissue mass image in the distal right ureter, a primary transitional cell carcinoma.

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Aug 2, 2016 | Posted by in GENERAL | Comments Off on Dilated Renal Calices
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