Renal Sinus Lesion



Renal Sinus Lesion


Michael P. Federle, MD, FACR



DIFFERENTIAL DIAGNOSIS


Common



  • Renal Sinus Lipomatosis



    • Renal Lipomatosis


  • Renal Sinus Cysts


  • Urolithiasis


  • Renal Trauma


  • Coagulopathic (“Retroperitoneal”) Hemorrhage


  • Vascular Lesions



    • Renal Artery Aneurysm


    • Arteriovenous Malformation, Renal


    • Renal Hilar Varices or Shunt


  • Transitional Cell Carcinoma


Less Common



  • Lymphoma


  • Other Renal Tumors



    • Renal Cell Carcinoma


    • Multilocular Cystic Nephroma


    • Renal Metastases


    • Squamous Cell Carcinoma


    • Rare Renal Tumors


  • Xanthogranulomatous Pyelonephritis


  • Fungal Infection, Renal


Rare but Important



  • Sarcoma, Retroperitoneal


  • Neurogenic Tumor, Retroperitoneum


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Renal sinus is extension of perirenal space



    • Contains multiple structures, any one of which can give rise to a mass lesion



      • Pelvo-calyceal system (e.g., transitional cell carcinoma, blood clot, fungus ball)


      • Major vessels (e.g., renal artery aneurysm, AVM, varices)


      • Lymphatics (e.g., lymphoma, lymph node metastases)


      • Nerves (e.g., neurogenic tumor)


    • CT, MR, & US easily distinguish many lesions that have similar appearance on IV urography



      • Can depict blood vessels, parenchymal lesion extent, etc.


      • Urography or pyelography may still be the best means of studying lesions of the renal pelvis (collecting system)


Helpful Clues for Common Diagnoses



  • Renal Sinus Lipomatosis



    • Increases gradually with aging, obesity, & loss of parenchyma due to disease


  • Renal Lipomatosis



    • In setting of chronic infection or obstruction


    • Proliferation of fibrofatty tissue may expand renal sinus



      • May displace calyces, vessels in hilum


    • Some degree of renal sinus fibrolipomatosis is found in all causes of renal parenchymal atrophy


  • Renal Sinus Cysts



    • Peripelvic = multiple confluent, noncommunicating cysts



      • Surround and compress calices, displace blood vessels


      • Often bilateral


      • Easily confused with hydronephrosis on US & NECT


    • Parapelvic = usually solitary, spherical



      • Usually unilateral


      • Often found with other simple cortical cysts


  • Urolithiasis



    • All are very dense (& echogenic) on CT, US



      • Except indinavir-induced stone in AIDS


    • Uric acid and xanthine stones are lucent on radiography



      • May appear as lucent filling defects within contrast-opacified renal pelvis on urography


  • Renal Trauma



    • May result in clot in renal pelvis, renal hilar hematoma or urinoma



      • Consider iatrogenic trauma (e.g., extracorporeal or percutaneous lithotripsy)


  • Coagulopathic (“Retroperitoneal”) Hemorrhage



    • May rarely result in spontaneous renal bleeding limited to blood filling renal pelvis


    • Blood will have attenuation of 45 to 65 HU on NECT, will not enhance


  • Vascular Lesions



    • Consider aneurysm, arteriovenous malformation (AVM), renal varices, & splenorenal shunt (portal hypertension)




      • Aneurysm: Look for calcification in arterial wall


      • AVM: Look for turbulent flow on color Doppler US, premature filling of renal vein on CECT and angiography


      • Renal varices: Varices & spontaneous or surgically-created splenorenal shunts are common in patients with cirrhosis & portal hypertension


  • Transitional Cell Carcinoma



    • Often slightly hyperdense on NECT, may have speckled calcification



      • Enhanced moderately with IV contrast administration


      • Often amputates (prevents filling of) calyces


    • Difficult to distinguish from squamous cell or mesenchymal tumors of renal pelvis


    • Higher incidence in patients who have had TCC of bladder or ureter previously


Helpful Clues for Less Common Diagnoses



  • Lymphoma



    • Generalizes abdominal involvement by non-Hodgkin lymphoma


    • Often involves renal hilar nodes


    • May extend into renal parenchyma


    • May invade parenchyma from outside or involve only the renal parenchyma (uncommon)



      • In latter case, consider immunocompromised state (e.g., AIDS or transplant recipient)


  • Other Renal Tumors



    • Renal Cell Carcinoma



      • Arises in cortex but may extend into renal sinus


      • May invade renal vein and IVC


      • May invade renal pelvis


      • More vascular and exophytic than TCC


    • Multilocular Cystic Nephroma



      • Multiseptate mass in young boy or middle-aged woman


      • Usually herniates into & distorts renal sinus


      • Cyst contents do not enhance but septa do


    • Rare Renal Tumors



      • Squamous cell, mesenchymal (e.g., sarcoma), etc.


      • Have overlapping features with renal cell carcinoma


      • Usually cannot be diagnosed confidently by imaging alone


  • Xanthogranulomatous Pyelonephritis



    • Some overlapping features with fibrolipomatosis, but XGP has more replacement of parenchyma with the foam cells (lipid-laden macrophages)


    • Kidney, or affected portion, is usually nonfunctional & obstructed by a large calculous


  • Fungal Infections, Renal



    • Usually in debilitated patients


    • May form “fungus ball” in renal pelvis


    • Diagnosis made by obtaining tissue & culture from urine & uroepithelium






Image Gallery









Axial CECT shows mass-like expansion of the left renal sinus with fibrolipomatous tissue, & dilated calices image due to a chronic partial obstruction of the left ureteropelvic junction by calculi.






Axial CECT shows left peripelvic cysts image. The renal vessels and calices are stretched around these cysts.







(Left) Axial CECT shows a large parapelvic cyst image that distorts the renal sinus. (Right) Frontal excretory urography shows marked scarring of the right renal pelvis with a stricture image causing dilation of the upper pole calices, due to recurrent renal calculi treated with lithotripsy.
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Aug 2, 2016 | Posted by in GENERAL | Comments Off on Renal Sinus Lesion
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