Diagnostic Ultrasound - Abdomen and Pelvis

Solid Renal Mass
• Horseshoe Kidney
○ Congenital renal anomaly where lower poles of kidneys
are fused by isthmus
○ Elongated kidneys with medially located lower poles
○ Lower poles curve away from transducer
○ Isthmus can consist of normal parenchyma or fibrous
band
– Usually anterior to aorta and IVC at L3/5 level
• Crossed Fused Ectopia
○ Mass with renal type morphology arising from lower
renal pole
○ Absence of kidney in contralateral renal fossa
• Renal Lymphoma
○ Variable manifestations
– Solitary or multiple hypoechoic hypovascular masses
– Direct invasion from retroperitoneal lymphoma
– Diffuse infiltration with renal enlargement
– Perinephric soft tissue rind
– Renal sinus dominant
○ Lesions are often hypoechoic or near anechoic
(pseudocystic)
○ Less vascular than renal cell carcinoma
○ Infrequently associated with renal vein and IVC tumor
thrombosis
• Renal Leukemia and Myeloma
○ Multifocal or infiltrative hypoechoic masses
○ Associated with tumor elsewhere and lymphadenopathy
• Renal Metastases
○ Most commonly secondary to lung cancer followed by
breast, gastrointestinal tract cancers, and melanoma
○ Typically small and round; occasionally wedge-shaped
○ Usually cortical, rarely disrupting renal contour or capsule
○ Variable echogenicity and may be isoechoic
○ Mostly avascular or hypovascular on color Doppler
○ Look for other evidence of disseminated disease, e.g.,
liver, lymph node, lung involvement
• Other Renal Tumors
○ No specific imaging findings
○ Oncocytomas may have central scar
• Wilms Tumor
○ Most common primary renal tumor in children > 1 year
old, most presenting < 5 years of age
○ Similar to renal cell carcinoma
Helpful Clues for Less Common Diagnoses
• Xanthogranulomatous Pyelonephritis (XGP)
○ Chronic renal inflammation associated with longstanding
urinary calculus and obstruction
○ Destruction and replacement of renal parenchyma by
lipid-laden macrophages
○ Anechoic/hypoechoic masses replacing normal
parenchyma ± abscesses
○ Associated with highly reflective central echocomplex
containing calculus
○ Hydronephrosis and cortical thinning
○ Clinical context essential
• Renal Sinus/Replacement Lipomatosis
○ Severe renal atrophy with proliferation of fat in renal
hilum and perirenal space
○ Hypoechoic poorly defined masses in renal sinus
○ Associated with calculus disease, chronic inflammation,
and hydronephrosis
○ Confirm with CT or MR
○ Distinct from XGP as renal parenchyma does not contain
lipid-laden foamy cells
• Renal Tuberculosis
○ Hematogenous spread of Mycobacterium tuberculosis
from primary focus, usually lungs
○ Hydronephrosis, infundibular strictures, caseating
cavities, calcification
• Renal Papillary Necrosis
○ Edematous papilla surrounded by fluid
○ Hydronephrosis from sloughed papilla
○ Later fluid-filled cavity communicating with renal pelvis
Differential Diagnoses: Kidney
Renal Cell Carcinoma
Renal Cell Carcinoma
(Left) Longitudinal ultrasound
shows a large, solid renal mass
, which contains central
shadowing calcifications ſt.
The upper pole of the kidney
st is atrophic and increased in
echogenicity secondary to
chronic kidney disease. (Right)
Longitudinal ultrasound shows
a solid, hypoechoic renal mass
, which exerts mass effect
on the renal sinus fat st. The
patient presented with diffuse
metastatic disease, and tissue
diagnosis was made by
percutaneous renal mass
biopsy.
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