Diagnostic Ultrasound - Abdomen and Pelvis

Upper Tract Urothelial Carcinoma
TERMINOLOGY
Abbreviations
• Upper tract urothelial carcinoma (UTUC)
Synonyms
• Upper tract transitional cell carcinoma (TCC)
Definitions
• Malignant tumor of transitional epithelium extending from
calyces to ureteral orifices
IMAGING
General Features
• Best diagnostic clue
○ Intraluminal mass or focal urothelial thickening in any
part of collecting system
○ Multicentric with synchronous tumors in upper urinary
tract and bladder
○ Diffusely infiltrating renal mass with preservation of
renal contour
• Location
○ Renal pelvis 8%, ureter 2%, (90-95% of UC occurs in
bladder)
○ 2-4% of patients with bladder cancer develop UTUC;
40% of patients with UTUC develop bladder cancer
Ultrasonographic Findings
• Grayscale ultrasound
○ Less sensitive than CT for identifying or characterizing
renal masses
○ Soft tissue mass in echogenic renal sinus, which may be
hyper-, iso- or hypoechoic to renal parenchyma
– Markedly hyperechoic due to squamous metaplasia
with formation of keratin pearls, non-shadowing
○ Typically causes hydronephrosis and calyceal dilatation
– Difficult to visualize if small and nonobstructing
○ More aggressive tumors may infiltrate diffusely but
preserve renal contour
– May be indistinguishable from renal cell carcinoma
(RCC), lymphoma, or metastases
○ Focal hypoechogenicity of adjacent renal cortex reflects
local invasion
○ Contrast-enhanced US: Slow wash-in, fast wash-out and
low enhancement degree typical
○ Upper ureter
– Focal urothelial thickening with secondary
hydronephrosis
• Color Doppler
○ Most hypo- or avascular; lack of vascularity does not
exclude TCC
○ Detection of internal color flow excludes blood clot,
fungus ball, pus, calculi
Pyelography
• Intravenous pyelography superseded by CT urography
(CTU)
• Retrograde pyelography performed during cystoscopy and
ureteroscopy
• Renal pelvis
○ Single or multiple discrete filling defects; surface is
usually irregular, stippled, serrated or frond like
○ Stipple sign: Contrast within interstices of tumor
○ Oncocalyx: Ballooned tumor-filled calyx
○ Phantom calyx: Unopacified calyx from obstruction of
calyceal infundibulum
• Ureter
○ Smooth or irregular, eccentric or circumferential
stricture, non-tapering margins, filling defects
○ Champagne glass/goblet sign: Dilatation distal to luminal
tumor caused by slow growing tumor expanding
ureteral lumen
CT Findings
• CECT
○ Hypovascular infiltrative tumor with minimal
enhancement; preserved renal shape
○ Sessile, flat, or polypoid solid mass ± hydronephrosis ±
calcification
○ Invasion of renal sinus fat and parenchyma
○ Fine encrusted calcifications that may be mistaken for
renal calculi
• CT urography
○ Superior to excretory urography or ultrasound
○ Eccentric or circumferential wall thickening or mass of
renal pelvis or ureter
○ Focal filling defects ± hydronephrosis
○ Crust-like rims: Contrast in curvilinear calyceal spaces
around periphery of tumor
MR Findings
• Alternative to CTU in patients with iodinated contrast
allergy
• Combination of T2-weighted and contrast-enhanced
sequences for optimum sensitivity
• Isointense to the renal parenchyma on T1- and T2WI
• Enhancing lesion with similar morphology as described for
CT
• Diffusion-weighted sequences may add value when
contrast cannot be used
Imaging Recommendations
• Best imaging tool
○ Upper tract tumors detected primarily using CTU
○ CT preferred for staging or follow up, although MR/U is
viable alternative
○ Chest imaging important for staging and follow up as
lung most common site of visceral metastases
• Protocol advice
○ Vigilant monitoring for metachronous lesions and local
recurrence for UTUC
DIFFERENTIAL DIAGNOSIS
Renal Cell Carcinoma (RCC)
• Usually hypervascular and more heterogeneous
(solid/cystic/calcified); vascular invasion more typical
• Difficult to distinguish infiltrative RCC from TCC
• However, RCC is more exophytic and has mass effect with
contour distortion
Blood Clot or Hemonephrosis
• Same echogenicity as tumor but mobile, avascular, and
resolves over time
Diagnoses: Urinary Tract
505