Renal Cysts



Renal Cysts


Sara M. O’Hara, MD, FAAP



DIFFERENTIAL DIAGNOSIS


Common



  • Multicystic Dysplastic Kidney (MCDK)


  • Ureteropelvic Duplications


  • Simple Renal Cyst


  • Autosomal Dominant Polycystic Renal Disease (ADPCKD)


  • Calyceal Diverticulum


  • Cystic Renal Dysplasia


Less Common



  • Autosomal Recessive Polycystic Renal Disease (ARPCKD)


  • Acquired Cystic Kidney Disease


  • Renal Injury


Rare but Important



  • Tuberous Sclerosis (TS) Complex


  • Multilocular Cystic Nephroma (MLCN)


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Cystic lesions of kidney in pediatric populations are seldom malignant



    • Cystic forms of renal cell, clear cell, and Wilms tumors are exceptions


  • Narrowing differentials



    • Unilateral



      • MCDK, duplication, simple renal cyst, calyceal diverticulum, trauma, MLCN


    • Bilateral



      • ADPCKD, ARPCKD, post-transplant acquired cystic disease, TS


    • Variable



      • Cystic dysplasia, duplications


Helpful Clues for Common Diagnoses



  • Multicystic Dysplastic Kidney (MCDK)



    • Classic type: Conglomerate cysts without discernible renal pelvis


    • Hydronephrotic type: Central cyst thought to be remnant of obstructed pelvis


    • High incidence of contralateral renal abnormalities: UPJ obstruction and vesicoureteral reflux (VUR)


    • MCDK initially large, but vast majority shrink over course of years


    • 1/2 of all MCDK have involuted by age 5


    • 12 reported cases of Wilms and renal cell carcinoma occurring in MCDK


    • National MCDK Registry tracks incidence and behavior


    • Imaging: Confirm lack of function with nuclear renal scan


  • Ureteropelvic Duplications



    • Upper poles of duplex kidneys tend to obstruct due to



      • Ectopic ureteral insertion


      • Ureterocele


      • Search bladder and pelvis carefully for ectopic ureter when evaluating upper pole cystic lesions


    • Lower poles have high incidence of VUR



      • Note: High-grade VUR may dilate calyces


    • Imaging: US, VCUG, diuretic renal scan


  • Simple Renal Cyst



    • Smooth, sharply marginated, water-density lesions


    • Through transmission on ultrasound


    • Does not enhance on CT and MR


    • If positive family history of cystic kidneys, consider ADPCKD


    • Imaging: US, CT, MR


  • Autosomal Dominant Polycystic Renal Disease (ADPCKD)



    • Hereditary disorder of renal cysts and other organ abnormalities



      • Renal cysts (100%)


      • Liver cysts (50%)


      • Pancreatic cysts (9%)


      • Brain/ovary/testis (1%)


      • Cardiac valvular disease (26%)


      • Cerebral aneurysms (5-10%)


    • Cyst visibility and prevalence increase with age


    • 1/2 of patients have cysts in 1st decade, 72% in 2nd


    • Prognosis



      • Excellent in childhood


      • Variable in adulthood: Based on degree of renal insufficiency and hypertension


    • Imaging: US, CT, MR, nuclear for function


  • Calyceal Diverticulum



    • Urine-filled eventration of calyx into renal parenchyma connected by narrow channel


    • Smooth, round to ovoid, thin walled; abuts calyx


    • May contain stones or debris


    • Delayed contrast excretion into diverticulum is diagnostic but not always seen



    • Imaging: US, CT, MR, nuclear renal scan


  • Cystic Renal Dysplasia



    • Generally progressive scarring and nephron loss due to repetitive injury



      • Vesicoureteral reflux


      • Pyelonephritis


      • High bladder pressure


      • Vascular compromise


      • Toxins, medications, radiation, etc.


    • Corticomedullary differentiation lost, increased echotexture, cysts


    • Imaging: US, CT, MR, nuclear renal scan


Helpful Clues for Less Common Diagnoses



  • Autosomal Recessive Polycystic Renal Disease (ARPCKD)



    • Single gene disorder (PKHD1)


    • Bilateral, enlarged, microcystic kidneys


    • Ectatic distal convoluted tubules and collecting ducts


    • Renal insufficiency/failure


    • Associated lung disease, oligohydramnios, MSK abnormalities


    • Prognosis is poor, but mild form may survive childhood


    • Imaging: US pre- and post-natally


  • Acquired Cystic Kidney Disease



    • Seen in almost 1/2 of patients on dialysis and with post solid organ transplant


    • Increased incidence with cyclosporin immune suppression


    • Screening important: ESRD and renal transplant patients have increased incidence of renal cell carcinoma


    • Clinical history narrows differential


    • Imaging: US, CT, MR


  • Renal Injury



    • Cystic change in kidney from trauma or infection


    • Cysts will not meet “simple” criteria



      • Have irregular walls, debris, septations


    • Without associated mass or enhancement, safe to follow with imaging


    • Imaging: US, CT, MR, nuclear renal scan


Helpful Clues for Rare Diagnoses



  • Tuberous Sclerosis (TS) Complex



    • Neurocutaneous syndrome: Hamartomatosis


    • Classic triad: Adenoma sebaceum, seizures, and mental retardation


    • Organs involved: Cardiac rhabdomyoma, lung lymphangiomyomatosis, renal cysts and angiomyolipomas, nonrenal hamartomas


    • Imaging: US, CT, MR, nuclear renal scan


  • Multilocular Cystic Nephroma (MLCN)



    • Benign cystic renal neoplasm


    • Bimodal age distribution



      • M > > F, 3 months to 2 years


      • M < < F, 5th and 6th decades


    • Imaging: US, CT, MR


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Aug 10, 2016 | Posted by in PEDIATRICS | Comments Off on Renal Cysts

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