This document discusses various imaging modalities used to evaluate renal masses, including plain radiography, intravenous urography, ultrasound, computed tomography, magnetic resonance imaging, and renal arteriography. For each modality, it describes their utility in detecting and characterizing renal masses and differentiating renal cell carcinoma from other lesions. It also provides examples of imaging findings for various renal pathologies such as abscesses, cysts, angiomyolipomas, and others.

1. Dr. Yash Kumar Achantani
OSR

2. 1. Plain abdominal radiography
2. Intravenous urography
3. Radionuclide imaging
4. Ultrasound
5. Computed tomography
6. Magnetic resonance imaging
7. Renal arteriography
8. Needle aspiration

3. The plain abdominal radiograph (KUB—kidneys, ureters,
bladder) is rarely used to diagnose a renal mass.
Loss of the psoas margin or displacement of retroperitoneal fat
may suggest the presence of one, as may an opacity projected
over the renal outline, or a loss of the renal outline.
Central calcification within a renal mass is more suggestive of
malignancy than peripheral calcification (87% versus 20–30%).

4. Intravenous urography (IVU) is a relatively insensitive method
of detecting small renal masses, particularly if they occur
centrally rather than peripherally; cross-sectional techniques
are a more appropriate method of investigating a patient with
a suspected renal mass.

5. Differentiation between a definite mass and an anatomical
variant that simulates a mass (pseudotumour) can be made
using radionuclide imaging; however, this is rarely useful in
practice.

6. US is usually the first method of evaluating a patient for a renal
mass and is the most appropriate technique for investigation of
a patient with an abnormal IVU.
Ultrasound is particularly useful in the investigation of children,
pregnant women and patients with renal impairment.
It can reliably differentiate solid masses from simple cysts,
which are the most common space-occupying lesions in the
kidney.
A lesion that appears solid on ultrasound, or demonstrates any
suspicious features, merits further analysis with CT or MRI.

7. Ultrasound is less accurate in staging renal cell carcinoma than
CT or MRI. It is poor at demonstrating lymph node disease and
skeletal or lung metastases.

8. When CT scanning is performed specifically to evaluate a
known renal mass, the study must include an unenhanced
examination prior to the administration of intravenous contrast
material.
By using a power injector, administer 150 mL of intravenous
contrast material (75 mL for patients with a single kidney)
injected at a minimum rate of 3 mL/sec to ensure that a high
concentration of contrast material is present within the renal
parenchyma during the post-contrast acquisition.

9. By using a multi–detector row CT scanner, contrast material–
enhanced imaging is routinely performed during the
corticomedullary and nephrographic phases of enhancement by
using scanning delays of 40 and 100 seconds, respectively.
The corticomedullary phase of enhancement is used to perform
three-dimensional (3D) reconstructions and to depict the renal
vasculature for urologists who perform laparoscopic
nephrectomy.
This phase is also useful to help differentiate a renal
pseudotumor from a renal neoplasm

10. (A) Nephrotomogram of IVU demonstrates loss of the normal lateral
contour of the left kidney and calyceal splaying. (B) Ultrasound
demonstrates a homogeneous mass of reduced reflectivity

11. C. CT confirms the presence of an enhancing mass with a necrotic
centre in keeping with a renal cell carcinoma.

12. Renal call carcinoma and inferior vena cava (IVC) tumour. Coronal
MRI demonstrates a large tumour thrombus in the IVC in a patient
with a large right-sided renal cell carcinoma.

13. Calcified renal cell carcinoma. (A) Ultrasound demonstrates a well-
defined lesion in the upper pole of the right kidney with increased
reflectivity. There is some minor posterior shadowing. (B) Intravenous
urogram demonstrates a calcified peripheral mass in the kidney with no
distortion of the calyceal system.

14. (C) CT before contrast administration demonstrates the lesion to be
heavily calcified. (D) The lesion is almost completely obscured on the
corticomedullary phase CT images, demonstrating the benefit of the
precontrast images.

15. The ability of MRI to characterize renal masses has improved
with the development of phased-array multicoils, fast breath-
hold imaging and the use of gadolinium-DTPA contrast
enhancement.
Protocols vary widely but usually include pre- and postcontrast
T1-weighted images with and without fat suppression.
The coronal and sagittal planes are helpful for evaluating the
extent of lesions. MR angiography can demonstrate the renal
arteries and veins, and the inferior vena cava.

16. Although simple renal cysts and angiomyolipomas have
characteristic appearances, the signal from most other masses is
nonspecific.
MRI is a good alternative to CT in patients with renal
insufficiency or previous reactions to contrast medium and is
superior to CT in differentiating benign thrombus from tumour
thrombus and in identifying its extent.
MRI is ideally suited for monitoring patients who have a
genetically increased risk of renal malignancy, such as von
Hippel–Lindau disease, who require regular follow-up.
It is no more specific than CT at differentiating malignant from
reactive lymphadenopathy

17. Renal arteriography is seldom used to diagnose or
characterize a renal mass as the necessary information is
usually provided by cross-sectional imaging.
Angiography may very occasionally still have a role in
preoperative planning when partial nephrectomy is being
considered, although CT angiography or MR angiography can
usually provide an adequate ‘road map’.

18. Percutaneous aspiration of renal cysts is indicated in the
investigation of an indeterminate cystic renal mass, to
diagnose an abscess or an infected cyst, and to confirm the
presence of malignancy in a patient who is not a candidate for
surgery.
The aspirated fluid should be sent for cytological examination,
although negative cytology does not exclude malignancy; this
applies particularly in some cystic renal cell carcinomas, in
which malignant disease is confined to the wall of the lesion.
If the fluid is found to be turbid, microbiological examination
should be performed.

19. A number of non-neoplastic tumours must be differentiated from
renal cell carcinoma.
Fetal lobulation occurs as a result of incomplete fusion of the fetal
lobules, which results in a lobulated contour to the lateral border
of the kidney, occurring between the underlying calices.
Dromedary humps are bulges occurring on the lateral side of the
left kidney. Many of these pseudotumours can be identified with
ultrasound but occasionally further investigation is necessary. CT
or radionuclide studies using 99mTc-DMSA can be useful.
Normal variants are composed of functioning renal tissue and
therefore exhibit excretion of isotope or contrast identical to the
rest of the kidney.

21. This is the commonest form of cystic disease and is seen with
increasing frequency with advancing age.
On ultrasound examination renal cysts appear as anechoic, well-
defined masses, with thin walls and good through transmission of
sound.
On CT a simple cyst usually appears as a well-defined rounded mass
with an attenuation value of 0–20HU, with an imperceptible wall
and no enhancement after injection of contrast medium.
The MRI appearance of a simple renal cyst is characterized by a
sharply demarcated, homogeneous, hypointense mass on T1-
weighted images, which becomes uniformly hyperintense on T2-
weighted images, and shows no enhancement following contrast
medium administration.

22. A classification of cystic lesions was suggested in 1986 by
Bosniak, based upon CT characteristics, and is used to guide
management.
Class I is a simple benign cyst.
Class II cysts have one or more thin (< 1 mm) septa running
through them, thin areas of mural calcification, or fluid contents
of increased attenuation; they do not enhance following
injection of contrast medium and are benign.

23. Class III cysts are more complicated and contain thickened septa,
nodular areas of calcification, or solid nonenhancing areas. Such
lesions are considered suggestive of malignancy and should be
biopsied or surgically explored although fewer than half will turn
out to be malignant.
Class IV cystic masses are clearly malignant, with solid enhancing
nodules or irregular walls, and should be treated accordingly.
A subcategory, IIF, has been suggested for lesions with multiple
class II features, and these require follow-up.

24. Ultrasound demonstrates a well-
defined lesion with no internal
echoes and enhanced through
transmission. There are fine foci of
linear calcification in the wall, making
the lesion Bosniak class II.
Bosniak class II cyst. Coronal
post contrast CT. This complex
cyst in the right kidney was
difficult to evaluate in the axial
plane and best examined in
this coronal section.

25. Cystic renal cell carcinoma. (A) Precontrast image demonstrates a homogeneous
low-attenuation mass in the left kidney. (B) Postcontrast image demonstrates a
small peripheral nodule of enhancing tumour in the wall of the cyst (Bosniak
class IV).

26. A simple benign cyst on ultrasound or CT requires no further
follow-up.
If there is wall thickening or the contents of the cyst are not of
water density, the lesion is indeterminate.
Haemorrhage or infection may result in cyst fluid of high
attenuation but, unlike tumours, such lesions do not enhance
following the administration of contrast medium.
Ultrasound is helpful only if the hyperdense mass satisfies the
ultrasound criteria of a benign simple cyst.

27. CT of haemorrhagic renal cyst. (A) Precontrast image reveals a high-density,
round, smooth mass in the left kidney. (B) Following contrast medium there is
no significant change in the appearance or density of the mass.

28. These occur in the renal sinus and frequently cause distortion,
but rarely obstruction, of the renal collecting system.
Peripelvic cysts are of lymphatic origin, whereas parapelvic cysts
are renal serous cysts arising from the renal parenchyma that is
present in the sinus.
Although parapelvic cysts may be evaluated satisfactorily using
ultrasound, peripelvic cysts can occasionally lead to confusion
with hydronephrosis, as they track along the renal infundibula.
Careful examination should demonstrate that the apparently
dilated infundibula do not connect to a dilated renal pelvis. If
necessary, urography or CT is usually confirmatory.

29. This is an autosomal dominant condition, which affects many
organs in addition to the kidneys.
Renal cysts are seen in addition to cysts within the liver,
pancreas and spleen.
Ultrasound demonstrates cysts in the adolescent or young
adult, who is usually not yet clinically symptomatic.
The full-blown disease presents with bilaterally enlarged
kidneys with numerous cysts of varying sizes.

30. Occasionally, an infected cyst, a hyperdense cyst and, less
commonly, a renal neoplasm may coexist with adult polycystic
renal disease and the diagnosis becomes somewhat difficult in
these cases.
MRI may prove to be a useful technique in differentiating
between simple cysts, haemorrhagic cysts and neoplasms
when the findings on CT and ultrasound are equivocal.

31. ADPKD- CT delayed contrast and Fat
sat T2 images showing hepatic and
renal involvement.

32. This is a nonhereditary, congenital, usually unilateral form of
renal cystic disease and is one of the commonest causes of an
abdominal mass in the newborn.

33. This is characterised by presence of multiple cysts throughout
or part or all of one kidney.
Normal cortex is seen between the individual cysts as oppsed to
multicystic renal dysplasia.
The contralateral kidney is usually entirely normal and even if
involved contains multiple tiny cysts , this feature helps to
differentiate it from ADPKD.
It is distinguished from multilocular cystic nephroma by the
presence of normal parenchyma b/w the cysts,

34. CT scan slightly inferior to A shows
multiple simple cysts separated by
attenuated renal tissue (arrow).

35. They are thick-walled, mainly intrarenal and sometimes
calcified .
Hydatid cysts may present as flank or perinephric masses,
which rupture into the collecting system, giving rise to acute
flank pain followed by the voiding of hydatid scolices, with or
without haematuria.
Ultrasound demonstrates a multicystic lesion of mixed
reflectivity.

36. Hydatid disease of the kidney. There is a cystic mass in the left kidney with a
multiloculated internal appearance from the presence of many daughter
cysts. The mass is causing marked pelvicalyceal dilatation.

38. Most abscesses are due to ascending infection, commonly by
Escherichia coli.
Immunocompromised and diabetic patients, as well as those
with infected renal stones, are at a higher risk of developing
renal infection.
Haematogenous infection is usually secondary to
Staphylococcus.
Rupture of a renal abscess can lead to infection of the
perinephric space.

39. CT is the best technique for the diagnosis and staging of renal
and perinephric abscess.
The central portion of an abscess is of near fluid density and
does not demonstrate contrast enhancement, making it more
obvious following contrast administration.
There is often a thick irregular wall, which enhances together
with inflammatory changes in the perinephric space.
The presence of gas within a lesion is diagnostic of an abscess
but is very rarely seen.
The differential diagnosis of these appearances includes renal
lymphoma, metastatic disease, renal infarction, and complicated
cystic disease.

40. Renal abscess. CT demonstrates a poorly enhancing mass in the right kidney in a
patient who had a severe urinary tract infection. The central fluid collection was
aspirated and found to contain pus. The mass resolved completely after antibiotic
therapy.

41. Focal pyelonephritis appears as a round or wedge-shaped
focal mass without a defined wall, which tends to extend from
the papilla to the outer cortex.
The administration of contrast medium demonstrates
heterogeneous enhancement of the affected area, which can
often be greater than that of the normal parenchyma on
delayed images. Perinephric inflammation is frequently seen.
CT may demonstrate persistent renal abnormality for several
weeks after infection and a focal mass may persist for several
months.

42. This is a rare disease of the renal parenchyma caused by
granulomatous inflammation.
Malacoplakia is most commonly seen in middle-aged women and
is more prevalent in individuals who are immunosuppressed.
Renal involvement is usually associated with disease in the lower
urinary tract.
Focal hypoechoic renal masses may simulate renal abscesses, and
heterogeneous masses that undergo calcification , may be
mistaken for renal carcinoma.
Renal malacoplakia can extend outside the kidney into the
perinephric space and can also undergo spontaneous
haemorrhage.

44. Renal haematoma may follow spontaneous intrarenal
bleeding or occur as a result of trauma. It may be difficult to
determine the cause.
The ultrasound appearance of a haematoma varies according
to its age. Fresh haematomas behave primarily as fluid
collections, whereas organized haematomas may be highly
reflective because they contain fragments of clot.
CT during the acute phase will demonstrate an area of high
attenuation, which is diagnostic of haematoma.

45. Two uncommon vascular lesions that may present as
intrarenal masses are aneurysms and arteriovenous
malformations (or fistulas).
The former is usually caused by atherosclerosis, but may be
congenital, post-traumatic, or secondary to vasculitis. Rim
calcification is common.
Arteriovenous communications are usually congenital, but may
be caused by trauma (particularly renal biopsy) or
atherosclerosis.

46. Angiomyolipomas are benign lesions composed of variable
amounts of fat, smooth muscle and abnormal blood vessels.
They occur mainly in women in the fifth decade. In patients
with tuberous sclerosis they occur at a much younger age and
are frequently multiple.
Angiomyolipomas are composed of thick-walled, inelastic blood
vessels. The risk of haemorrhage is related to the size of the
tumour, and is significantly higher in lesions greater than 4 cm
in diameter.

47. The appearance on ultrasound depends on the proportions of fat,
smooth muscle and vascular elements, and on the presence of
haemorrhage.
Typically, angiomyolipoma appears as a circumscribed, highly
reflective mass, more echogenic than the central sinus fat.
Because of this high reflectivity, very tiny lesions can be detected
with ultrasound.
Tumours with a greater proportion of muscle, and those that
have undergone haemorrhage or necrosis, may not be echogenic.
Renal carcinomas smaller than 3 cm in diameter are also highly
reflective, but the have a hyporeflective rim or small centeral
hyporelective areas and unlike angiomyolipomas they don’t show
posterior shadowing.

48. CT usually demonstrates a fatty mass intermixed with areas of
increased tissue density, detection by CT of even a small
amount of fat within a renal mass establishes the diagnosis of
angiomyolipoma.
If there is coexistent haemorrhage, CT and other techniques
may not provide an accurate preoperative diagnosis.
It is important to assess the relationship of the fat to the
remainder of the tumour to be certain that the fat is
intratumoral, and not peri renal fat that has been engulfed by
an expanding renal cell carcinoma.
Angiography can demonstrate multiple aneurysms and an
‘onion layer’ appearance. Embolization can control bleeding
tumours and can also be used to treat enlarging tumours to
reduce the risk of haemorrhage.

49. Multiple well defined homogeneously hyperechoic lesions with no
perilesional halo in both left and right kidneys— Angiomyolipomas

50. USG (A) and color Doppler (B) show a small well-defined hyperechoic
lesion in the right kidney with peripheral vascularity—
Angiomyolipoma

51. Angiomyolipoma. Axial CT demonstrates small areas of fat within
the right kidney consistent with an angiomyolipoma.

52. Bleeding angiomyolipoma. CT obtained following a severe attack of
abdominal pain demonstrates perirenal blood and inflammatory change
surrounding the right kidney following a spontaneous bleed. There is
central fat density (arrow) which suggests the presence of an
angiomyolipoma.

53. CECT showing large heterogeneous soft tissue masses in
both kidneys with fat density scattered throughout and
enlarged vessels—a case of tuberous sclerosis.

54. Sinus lipomatosis is an overabundance of normal renal sinus
fat, which may produce stretching of the infundibula and
compression of the renal pelvis, simulating a parapelvic cyst or
other hilar renal mass.
The diagnosis is generally made clear by CT or ultrasound. On
ultrasound examination the area in question is usually
echogenic.

57. Small renal tumours (< 3 cm) have been regarded in the past
as adenomas rather than carcinomas.
Unfortunately, the size of a renal mass is not a valid criterion
for differentiating a benign from a malignant mass.
There are reports of tumours that have produced metastases
when less than 3 cm, although this is uncommon.

58. Oncocytomas are tubular adenomas with a specific histological
appearance characterized by the oncocyte.
Oncocytomas can occur at any age and are often asymptomatic
at presentation. They can vary in size from 1 to 20 cm in
diameter, but tend to be large. Although they are usually solitary
and unilateral, they can be multiple (5%) and bilateral (3%).
Ultrasound demonstrates a solid mass with internal echoes,
which occasionally has a stellate hypoechoic centre. However,
the echogenicity of the mass can be variable.
Contrast-enhanced CT demonstrates a well-defined solid mass
which, when large, can contain a low attenuation central scar.

59. Large lesions can extend into and engulf the perinephric fat,
and can be mistaken for angiomyolipomas.
There are no features on MRI that will differentiate an
oncocytoma from renal carcinoma.

60. Oncocytoma. CT demonstrates multiple well-defined enhancing masses in
both kidneys which were confirmed by percutaneous biopsy to be
oncocytoma. Follow-up examination at 12 months did not demonstrate any
growth.

61. Haemangiomas of the kidney are rare lesions that are generally
cavernous rather than capillary. The most common symptom is
haematuria. They are most commonly symptomatic in the
middle years and are equally distributed between the sexes.
Excretory urography may demonstrate a renal mass or, more
commonly, pyelocalyceal distortion or a filling defect,
attributable to the haemangioma or associated clot. Selective
arteriography is often unhelpful, although occasionally will
suggest the diagnosis.

62. This rare benign neoplasm presents as a unilateral septated
encysted mass.
It usually presents in young children but can be seen in
adulthood, particularly in women. There are frequently septa
which demonstrate enhancement.
The cystic portion is usually of water density or slightly higher
density with no enhancement.
The best clue to the diagnosis is the presence of herniation of
the mass into the renal hilum.

65. Renal cell carcinoma is the commonest renal malignancy,
comprising 85% of all malignant renal tumours. It occurs
bilaterally in 3–5% of cases.
Most cases arise spontaneously in the fifth to seventh decade.
Renal cell carcinoma is seen in about 36% of patients with
von Hippel–Lindau disease .
There is also an increased incidence of renal cell carcinoma in
patients on long-term haemodialysis.

66. There are several main types as well as larger rare subtypes
of RCC out of which important ones are.
Clear cell carcinoma:- Commonest renal malignancy.
Characterised by significant enhancement following contrast
administration.
Papillary tumours:- Commonly seen in failing kidneys and not
infrequently multiple.
Show minimal contrast enhancement and thus can be difficult
to differentiate from a hyperdense cyst if precontrast not
done.
Chromophobe tumours:- Similar appearance as ocnocytomas
with homogenous enhancement and presence of central scar.
On USG appear as hyperechoic mass.

67. Plain radiographs show evidence of calcification in 5–10% of cases.
IVU may demonstrate distortion of the calyceal system. Absence of
contrast excretion is uncommon, and suggests tumour extension into
the renal vein.
Renal cell carcinoma can appear hyperechoic, hypoechoic, or
isoechoic on ultrasound. Most small renal carcinomas are
hyperechoic compared to normal parenchyma, whereas up to 86% of
large tumours are isoechoic. Central necrosis can produce a central
hypoechoic region that is associated with posterior acoustic
enhancement.
Cystic tumours may have thick or irregular walls together with small
or large intracystic nodules of tumour.
Ultrasound with colour Doppler is useful for detecting inferior vena
cava thrombus and extension of tumour thrombus into the
intrahepatic vena cava.

68. Renal cell carcinomas are often heterogeneous on unenhanced
CT, with one or more low-density central areas. An extensively
necrotic tumour may have a pseudocapsule. CT is the most
sensitive technique for the depiction of parenchymal
calcification associated with renal malignancy.
Most renal cell cancers are solid, with attenuation values of more
than 20HU on unenhanced CT images. An increase in attenuation
of more than 10HU after administration of contrast medium
suggests a solid mass, and enhancement of more than 20HU
indicates malignancy

69. MRI can be used to detect and stage renal cell carcinoma, with a
similar sensitivity to CT.
The signal characteristics of renal cell carcinoma are variable, with
tumours appearing isointense or hypointense compared to the renal
cortex on T1-weighted sequences, and slightly hyperintense on T2-
weighted sequences.
Following administration of gadolinium, heterogeneous
enhancement occurs immediately, decreasing on delayed images.
Homogeneous enhancement is more likely in small, low-grade
tumours.
In most institutions CT is the technique of choice for the diagnosis
and staging of renal cell cancer; MRI is used when contrast-enhanced
CT is contraindicated, or if frequent follow-up is required in high-risk
patients.

70. Disease extent TNM stage
Tumour confined to kidney, small < 4 cm T1a
Tumour confined to kidney > 4 cm, < 7 cm T1b
Tumour confined to kidney > 7 cm T2
Tumour spread to perinephric fat T3a
Tumour spread to renal vein or cava T3b
Tumour spread to cava above diaphragm T3c
Tumour spread outside Gerota's fascia T4
Metastasis in single lymph node N1
Metastasis in more than one lymph node N2
Distant metastasis M1

71. CT has a limited ability to identify lymph node involvement,
based entirely on size. Using 1 cm as the upper limit of normal.
Accurate identification of involvement of the renal vein and
inferior vena cava is very important for correct patient
management.
Optimal enhancement of the renal vein is seen during the
corticomedullary phase of enhancement. Thrombus is seen as a
filling defect within the vein.
It is usually difficult to differentiate tumour thrombus from
bland thrombus unless enhancement can be seen within the
thrombus.
MRI is superior to CT in differentiating benign from malignant
thrombus, but offers no advantage in staging nodal disease.

72. von Hippel–Lindau
and T1 renal cell
carcinoma. Coronal
reconstruction
demonstrates a T1
renal cell carcinoma
in the lower pole of
the right kidney
which was not
appreciated on the
axial imaging. There
is evidence of
previous nephron-
sparing surgery on
the left side.

73. Papillary carcinoma. Pre- (A) and post- (B) contrast CT demonstrates a large
poorly enhancing homogeneous mass seen in the left kidney that has the typical
appearances of a papillary tumour. These have a relatively indolent course. Care
must be taken not to diagnose these well-defined and homogeneous lesions as
cysts.

74. Advanced renal cell
carcinoma.
Coronal postcontrast
CT demonstrates
tumour thrombus
extending into the left
renal vein but not into
the cava (radiological
stage T3b). The
tumour was
discovered when the
patient presented
with new onset of a
varicocele.

75. A and B: Color Doppler: and spectral trace
show vascularity within and surrounding the mass

76. A and B: NCCT and CECT showing a large enhancing left renal mass with peripheral
and central coarse calcification in the left kidney

77. CT features of renal cell carcinomas in 4 phases: (A) Noncontrast, (B) Corticomedullary, (C)
Nephrographic, (D) Excretory phases.
Mass is best demarcated on nephrographic phase and shows “de-enhancement” in the later
phase

78. Pre and post contrast images Shows solid left renal mass with increase in attenuation of
20 HU-malignant etiology (RCC)

79. Renal cell carcinoma – MRI (A) T2 coronal (B) T1W1 axial showing
A well-circumscribed mass hypointense on T1 and hyperintense on T2
arising from upper pole of right kidney. IVC appears normal. Necrotic
change is noted appearing hyperintense on T2W images

80. MRI—TRU FISP axial (A) and coronal (B) Mixed intensity right
lower renal polar mass with areas of hemorrhage and well defined
‘pseudocapsule”

81. TI post gadolinium axial (C) and MPR (D) shows enhancing soft
tissue component of the mass

82. Sarcomas of the kidney are rare, solid, malignant tumours, which
develop from mesenchymal cells.
Many of these tumours arise in close proximity to the renal
capsule, making it difficult to distinguish whether they originate
in the renal or perinephric tissues.
The imaging characteristics are nonspecific, making it difficult to
distinguish a renal sarcoma from a renal cell carcinoma. The
tumours are frequently large at presentation and tend to present
with abdominal pain and discomfort. Renal vein and inferior vena
cava invasion are seen, and metastases are common at initial
diagnosis.

83. Primary lymphoma of the kidney is very rare, as there is no
lymphatic tissue within the kidneys.
Renal involvement may be due to haematogenous spread or
contiguous invasion from adjacent retroperitoneal
lymphadenopathy.
The kidneys are much more frequently involved in patients
with non-Hodgkin's lymphoma, particularly when the disease
has relapsed.

84. CT may demonstrate sheet-like diffuse infiltration of the
perirenal tissues or multiple focal nodules.
Following intravenous injection of contrast medium, focal
lesions are usually of low attenuation. Contrast enhancement
can also be useful in demonstrating the presence of discrete
focal abnormalities in diffusely enlarged kidneys.
Lymph node enlargement is often seen surrounding the vessels
and can lead to bilateral hydronephrosis.
Ga citrate radionuclide imaging may also identify
lymphomatous involvement of the kidney. CT- or ultrasound-
guided biopsy may be helpful if lymphoma is suspected.

85. Non-Hodgkin's lymphoma. (A) Unenhanced CT demonstrates homogeneous
enlargement of both kidneys. (B) Postcontrast examination demonstrates multiple
focal areas of reduced enhancement within the kidneys, consistent with
lymphoma. Hepatic and pancreatic deposits of lymphoma can also be seen.

86. USG bilateral renal enlargement with poorly defined
hypo/anechoic nodules giving a homogeneous appearance—
lymphoma

87. Contrast enhanced CT showing well defined focal hypodense masses in
both kidneys with significant retroperitoneal adenopathy and bowel
thickening—a case of lymphoma

88. CT abdomen—bilateral kidneys are enlarged with loss of
corticomedullary differentiation—a case of Burkitts
lymphoma

89. These tumours rarely cause symptoms during life but are frequently
found in autopsy studies.
Most renal metastases are haematogenous, although a few occur by
direct invasion or from lymphatic spread. The commonest primary
tumours are bronchial, colorectal, breast, testicular and
gynaecological malignancies, and malignant melanoma.
Haematogenous metastases are usually small (< 3 cm), multiple
and confined to the cortex.
They are usually hypovascular on CT and do not tend to
demonstrate calcification or renal vein invasion. Most metastases
are more infiltrative and less exophytic than renal cell carcinoma.

90. Renal metastases from a leiomyosarcoma. (A) Several low attenuation lesions
are seen in both kidneys in a patient with a past history of a pelvic
leiomyosarcoma. (B) Coexistent local tumour recurrence in the left side of the
pelvis.

91. MRI T1 vibe post contrast a focal poorly enhancing mass in the
right kidney (A), Renal metastasis from disseminated ovarian
malignancy (B)

94. TCC is the second most common renal neoplasm in adults. It is
most common in urinary bladder, followed in frequency by
ureter and pelvis.
The incidence of TCC is more common in males, in the seventh
decade. They commonly present with hematuria and flank
pain. Hematogenous spread is less common than RCC, but
lymphatic spread occurs earlier.

95. IVU
The findings include a filling defect outlined by excreted contrast.
The filling defect may be in pelvis (35%) or calyces (26%). ‘Stipple
sign’ may be seen due to trapping of contrast in the interstices of a
papillary growth. There may be obstruction of kidney with non
opacification of the collecting system (phantom calyx) due to
extensive areas of parenchymal infiltration.
USG
A large TCC is seen as an iso- to hypoechoic solid mass separating
the central sinus echoes. A small TCC may not be detected on USG.
Focal enlargement of renal cortex suggests infiltration of renal
parenchyma.
Longitudinal sonogram of the left kidney
shows a solid lesion in the renal pelvis and
upper ureter with consequent
hydronephrosis - Transitional cell carcinoma

96. CT and MRI
The most common appearance is of a small hypodense lesion in
the renal collecting system, the lesion has a soft tissue
attenuation (< 40 HU), less than most renal calculi, the
attenuation of TCC is slightly lower than a blood clot, but higher
than urine. TCC will enhance approx 10-50 HU, with the
enhancement being less than renal parenchyma. This mild
enhancement helps differentiate it from blood clot and calculi.
In the kidney, TCC is usually more central than RCC, owing to the
origin in the urothelium.
The central mass expands the kidney symmetrically and with
centrifugal extension preserves the shape.

97. TCC may present as a locally aggressive infiltrative renal mass,
margins being ill defined. Involvement of renal parenchyma may be
seen as a hypoenhancing mass involving parenchyma or
heterogeneous abnormal hypoenhancement disrupting the normal
parenchyma.
MR appearance TCCs are typically isointense relative to renal
medulla on T1WI on T2-weighted images seen as hypointense
filling defects.
Infitrative TCCs may be seen on single shot T2WI as
intermediate signal intensity mass infiltrating the renal
parenchyma. Enhancement of a focal filling defect in the
collecting system is strongly suggestive of TCC.
A cup-shaped dilatation of the ureter just distal to a focus of
TCC in the ureter may be seen which is called as
“chalice/goblet” sign.

98. MRI T2 coronal (A) T1, post-
gadolinium axial (B) and coronal (C)
shows an enhancing mass in the
renal pelvis with hydronephrosis
and retroperitoneal adenopathy—
TCC

99. Squamous cell carcinoma of the renal pelvis is relatively rare
tumor. It is highly aggressive, with a poor clinical prognosis.
It often involves the renal parenchyma and perinephric tissue
and may present with metastasis.
In cross sectional imaging, this cannot be differentiated from
transitional cell carcinomas. Pointers towards the diagnosis of
SCC include the fact that SCC grow fast, and rapid progression
on sequential studies favour SCC.