Diagnostic Ultrasound - Abdomen and Pelvis

Dilated Renal Pelvis
• Intrarenal Abscess
○ Hypoechoic parenchymal lesion, which may mimic
collecting system dilatation
○ May also be associated with hydronephrosis and
urothelial thickening
○ Most often secondary to acute pyelonephritis, but
relatively rare
• Calyceal Diverticulum
○ Typically upper pole, connects with calyx
– Lined with transitional cell epithelium
○ May appear like simple cyst or dilated calyx
○ Prone to calculus formation and infection: Containing
milk of calcium and debris
○ On excretory phase CT/ MR, VCUG, or retrograde
pyelography, diagnostic filling of diverticulum with
contrast
• Acute Renal Vein Thrombosis
○ Dilated vein with hypoechoic thrombus
– Chronic thrombosis often demonstrates greater
internal echogenicity and organized clot along walls
○ Absent venous color Doppler flow
Helpful Clues for Rare Diagnoses
• Pyelogenic Cyst
○ Similar to calyceal diverticulum but communicates with
pelvis rather than calyx
• Multilocular Cystic Nephroma
○ Encapsulated multilocular cystic renal lesion with internal
septa
– On MR/CT, note enhancement of septa
○ May herniate into renal pelvis, mimicking pelviectasis, or
may cause hydronephrosis
• Lucent Sinus Lipomatosis
○ Very rarely, renal sinus fat may appear less echogenic
than normal and mimic hydronephrosis or hypoechoic
mass
– Secondary to chronic steroid use, obesity, diabetes,
renal atrophy, and inflammation
○ More evident when there is chronic kidney disease and
hyperechoic kidneys
• Renal Lymphoma
○ Multiple forms, including hypoechoic infiltration of renal
sinus
– May mimic dilated renal pelvis or cause
hydronephrosis
• Retroperitoneal Lymphoma
○ Retroperitoneal adenopathy may demonstrate
contiguous extension into renal pelvis, mimicking
dilatation of collecting system
○ Distinct from renal lymphoma
• Renal Artery Aneurysm
○ Pulsatile fluid-filled structure with diagnostic
color/power Doppler
○ Typically small < 2 cm and saccular
○ Located at bifurcation of main renal artery
• Arteriovenous Malformation (AVM)
○ Congenital malformation which appears hypoechoic on
grayscale ultrasound
○ Color Doppler flow reveals hypervascular mass with
aliasing
• Intrarenal Varices
○ May present as cystic renal mass
○ May mimic hydronephrosis
○ Associated with AVM
• Renal Lymphangiomatosis
○ Multiple cystic lesions in both parapelvic and perirenal
areas
○ Related to lymphatic obstruction
SELECTED REFERENCES
1. Ma TL et al: Parapelvic cyst misdiagnosed as hydronephrosis. Clin Kidney J.
6(2):238-9, 2013
2. Darge K et al: Pediatric uroradiology: state of the art. Pediatr Radiol.
41(1):82-91, 2011
3. Sheth S et al: Imaging of renal lymphoma: patterns of disease with
pathologic correlation. Radiographics. 26(4):1151-68, 2006
4. Browne RF et al: Transitional cell carcinoma of the upper urinary tract:
spectrum of imaging findings. Radiographics. 25(6):1609-27, 2005
5. Rha SE et al: The renal sinus: pathologic spectrum and multimodality imaging
approach. Radiographics. 24 Suppl 1:S117-31. Review,2004
6. Nahm AM et al: The renal sinus cyst-the great imitator. Nephrol Dial
Transplant. 15(6):913-4, 2000
Differential Diagnoses: Kidney
Obstructed Renal Pelvis
Obstructed Renal Pelvis
(Left) Graphic shows an
obstructing polypoid tumor st
at the ureteropelvic junction.
The proximal ureter is dilated
around the tumor, producing
the goblet sign ſt. (Right)
Longitudinal ultrasound
demonstrates hydronephrosis,
with pelvic dilatation to a
greater degree than calyceal
dilatation ſt, consistent with
UPJ obstruction.
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