Diagnostic Ultrasound - Abdomen and Pelvis

Renal Metastases
Diagnoses: Urinary Tract
IMAGING
• Typically multiple and small, bilateral, hypoenhancing renal
masses
• More likely to be endophytic, compared to renal cell
carcinoma (RCC), which is more likely exophytic
• Large exophytic metastases may be encountered
• Mostly avascular or hypovascular
• Increased uptake in F-18-2-fluoro-2-deoxy-glucose (FDG)
scan
• Melanoma metastasis: Hypervascular; may stimulate RCC
• Perinephric infiltration from tumor extension or
hemorrhage may be seen (melanoma)
TOP DIFFERENTIAL DIAGNOSES
• Primary renal malignancy
• Renal angiomyolipoma
• Renal cyst
• Renal lymphoma or leukemia
• Renal infection
KEY FACTS
• Renal infarction
CLINICAL ISSUES
• Usually asymptomatic; may have hematuria or
microhematuria (12-31%)
• Most are clinically occult and found on imaging or at
autopsy
• Most common malignant renal tumor at autopsy (7-13% of
autopsies),20% of patients dying of disseminated
malignancy
• Lung cancer most common primary site followed by breast,
gastric cancer, melanoma, and lymphoma
• Prognosis very poor
DIAGNOSTIC CHECKLIST
• Multiple renal masses likely to be metastases in presence of
nonrenal primary cancer and widespread systemic
metastases
(Left) Longitudinal US of the
right kidney shows a mid pole
solid, homogeneous, slightly
hyperechoic mass
representing metastatic
melanoma. This cannot be
distinguished from renal cell
carcinoma (RCC). (Right)
Corresponding color Doppler
US shows no significant color
flow within the mass .
While the grayscale features
are indistinguishable from
RCC, metastases are typically
hypovascular compared to
RCC.
(Left) Color Doppler
ultrasound shows a large,
echogenic renal metastasis
, which is hypovascular.
There is preservation of the
renal contour. Renal
metastases are usually smaller
and less echogenic and may be
difficult to detect with
ultrasound. (Right)
Longitudinal US shows an
enlarged, globular kidney with
hypoechoic infiltration of the
cortex by multiple
myeloma. Note relative
preservation of the sinus fat.
498