Genito-Urinary System

Renal Tumors

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Tumors1-Classification2-Tumors in Adults3-Tumors in Pediatrics4-Renal Mass in the Newborn

1-Classification :(i) Renal parenchymal Tumors(ii) Mesenchymal Tumors(iii) Renal Pelvis Tumors(iv) Secondary Tumors

(i) Renal parenchymal tumors :1-Renal Cell Carcinoma (RCC) 2-Adenoma 3-Oncocytoma4-Wilm’s Tumor5-Nephroblastomatosis6-Mesoblastic Nephroma7-Clear Cell Sarcoma8-Rhabdoid Tumor of Kidney9-Multilocular Cystic Nephroma10-Reninoma

(ii) Mesenchymal Tumors :-Angiomyolipoma(iii) Renal Pelvis Tumors :1-Benign Tumors : Papilloma2-TCC3-Sqaumous Cell Carcinoma4-Collecting Duct Carcinoma(iv) Secondary Tumors :1-Metastases2-Lymphoma

(i) Renal Parenchymal Tumors :1-Renal Cell Carcinoma (RCC) 2-Adenoma 3-Oncocytoma4-Wilm’s Tumor5-Nephroblastomatosis6-Mesoblastic Nephroma7-Clear Cell Carcinoma8-Rhabdoid Tumor of Kidney9-Multilocular Cystic Nephroma10-Reninoma

1-Renal Cell Carcinoma (RCC) :a) Incidenceb) Clinical Picturec) Stagingd) Radiographic Features

a) Incidence :-Malignant tumors derived from the renal

epithelium-It is the most common malignant renal

tumor-M:F = 3:1

b) Clinical Picture :-Triad of :1-Macroscopic hematuria : 60%2-Flank pain : 40%3-Palpable flank mass : 30-40%

c) Staging :TNM staging (7th edition)-T1 : 4-7 cmT1a : limited to kidney <4 cm T1b : limited to kidney >4 cm but < 7 cm -T2 : 7-10 cmT2a : limited to kidney, >7cm but not more than

10cm T2b : limited to kidney > 10 cm

-T3 : tumor / tumor thrombus extension into major veins

T3a : spread to renal vein T3b : spread to infra diaphragmatic IVC T3c : spread to supra diaphragmatic IVC or

invades the wall of the IVC -T4 : involves ipsilateral adrenal gland or

invades beyond Gerota's fascia

-N :N0 : no nodal involvementN1 : metastatic involvement of regional

lymph node/s-M :M0 : no distant metastasesM1 : distant metastases

d) Radiographic Features :1-IVP2-U/S3-CT4-MRI5-Angiography

1-IVP :-Amputation of calyces-Focal contour bulge

2-U/S :-Hyperechoic or may be hypoechoic

IVU showing a mass in the lower pole of the right kidney causing calyceal distortion

3-CT :-Enhancing mass (heterogeneous)-Contour deformity-10 % with calcifications-May show cystic component (cystic renal cell carcinoma)-During the corticomedullary phase (25-70 seconds) of

enhancement following administration of contrast , RCC shows variable enhancement , the corticomedullary phase is also best for assessing vascular anatomy

-The nephrogenic phase (80-180 seconds) is the most sensitive phase for detection of abnormal contrast enhancement

-Excretory phase is of less worth but important in assessing the collecting system anatomy

RCC discovered incidentally in 83-year-old woman who underwent CT after a fall, transverse CT+C from corticomedullary phase shows brisk enhancement in 4-cm exophytic ball-type mass (arrows) at right upper pole, because of the patient's advanced age, biopsy was performed and conventional RCC was found

Renal cell carcinoma in a 43-year-old woman, (a) Unenhanced CT scan reveals a 2-cm-diameter hyperattenuating (70 HU) renal mass (arrow), (b) CT+C shows enhancement of the mass to 96 HU

Cystic RCC

4-MRI :*T1 : often heterogeneous due to necrosis ,

hemorrhage and solid components*T2 : appearances depend on histologyClear cell RCC , hyperintensePapillary RCC , hypo intense*T1+C : often shows prompt arterial

enhancement

T1+C

T1+C

5-Angiography :-95 % of tumors are hypervascular

2-Adenoma :-Best described as adenocarcinoma with no

metastatic potential-Usually detected at autopsy

CT+C in 60-year-old woman with hematuria shows hypoattenuating, expansile solid mass (arrows) in left kidney, radical nephrectomy showed mass to be metanephric adenoma. K = kidney

3-Oncocytoma :a) Incidenceb) Radiographic Features

a) Incidence :-5% of renal tumors -Although the majority of lesions are well

differentiated and benign , these tumors need to be resected because of their malignant potential and the inability to differentiate from RCC preoperatively

b) Radiographic Features :-Unfortunately the imaging appearance of

oncocytomas is difficult to distinguish from renal cell carcinoma and as such they are usually resected

-Helpful criteria is the sharply hypodense central scar (non-enhancing) , present only in third of cases and presence of calcification

CT+C shows a large well defined mass in the right flank , the mass is solid and enhances , a central stellate scar is present

Incidental discovery at CT of oncocytoma in 52-year-old woman undergoing evaluation after trauma, reconstructed sagittal contrast-enhanced corticomedullary-phase CT image shows ball-type mass with stellate central scar (arrow) arising from anterior interpolar region of left kidney, note presence of pseudocapsule at posterior margin of the mass. Pathologic diagnosis of oncocytoma was made after laparoscopic nephrectomy

64-year-old man with histologically proven oncocytoma. K = kidney. (a) Axial fat-saturated, T2-weighted gradient-refocused echo image shows expansile, solid right renal mass (arrow) with hyperintense central scar (S), (b) T1+C 3D gradient-refocused echo image shows right kidney mass (arrow) with hypointense central scar (S)

72-year-old man with hereditary oncocytosis syndrome, coronal CT+C during nephrographic phase shows bilateral solid renal masses (arrows) that were characterized as oncocytomas on histopathology

4-Wilm’s Tumor :a) Incidenceb) Clinical Picturec) Stagingd) Radiographic Featurese) Differential Diagnosis

a) Incidence :-Most common solid renal tumor of the

childhood-3rd most common malignant in children after

leukemia and brain tumors

b) Clinical Picture :1-Palpable abdominal mass2-Hypertension3-pain

c) Staging :-As RCC

d) Radiographic Features :1-U/S2-CT3-MRI

1-U/S :-Ultrasound is a very useful examination in

so far as it can distinguish between a cystic mass (e.g. hydronephrosis) and a solid mass

2-CT :-Large heterogeneous soft tissue density

masses (mean 12 cm) with :Cystic areas (hemorrhage & necrosis)Frequent areas of calcification (9%)Fat density regions-Enhancement is also patchy

Wilms tumor in a 4-year-old boy with an abdominal mass, (a) CT scan shows a left renal mass with heterogeneous enhancement (thick arrow) and multiple hepatic metastases (thin arrows), (b) CT scan obtained at a higher level again shows multiple hepatic metastases in addition to tumor thrombus within the portal veins (arrows)

Non-contrast CT+C

3-MRI :*T1 : hypointense*T2 : hyperintense*T1+C : heterogeneous enhancement

Wilms tumor in a 3-year-old boy with an abdominal mass, Gadolinium-enhanced coronal fat-suppressed T1 shows a large, well-defined mass in the right kidney (arrows) that enhances less than adjacent renal parenchyma and contains multiple hypointense hemorrhagic foci, the hypointense area in the medial spleen is due to partial volume artifact

e) Differential Diagnosis : From neuroblastoma1-Age : younger in neuroblastoma < 2 yrs2-Origin , Wilm's from kidney , neuroblastoma from the

retroperitoneal neural crest3-Renal mass effect : Wilm’s shows intrinsic mass effect ,

neuroblastoma shows external compression4-Calcification : more in neuroblastoma5-Vessel involvement : invasion in Wilm’s , encasement in

neuroblastoma6-Margins : well circumscribed in Wilm’s and poorly

marginated in neuroblastoma

5-Nephroblastomatosis :a) Incidenceb) Radiographic Features

a) Incidence :-Refers to diffuse or multifocal involvement

of the kidneys with nephrogenic rests-Present in 30 % of unilateral Wilms tumors

and in 100 % of bilateral Wilms tumors-Nephrogenic rests can be classified into :1-Perilobar rest (90 %)2-Intralobar rest (10 %) , more associated

with Wilms tumor 

b) Radiographic Features :1-U/S2-CT3-MRI

1-U/S :-Hypoechoic nodules

2-CT :-Nephrogenic rests appear as low

attenuation peripheral nodules with poor enhancement relative to that of adjacent normal renal parenchyma

Diffuse nephroblastomatosis, child with flank mass and hemihypertrophy. Nephroblastomatosis foci (yellow arrows), the surface of the kidney may reveal lobations

Nephroblastomatosis in a 16-month-old boy with an abdominal mass, (a) Plain radiograph shows displacement of bowel loops into the midabdomen by bilateral flank masses, (b) CT+C shows large, homogeneous Wilms tumors (W) superimposed on a background of multiple peripheral nephrogenic rests (arrowheads)

Axial CT+C of the abdomen (a) and pelvis (b) show the abnormally enlarged kidneys and a thick rim of plaquelike blastemal tissue, which demonstrates a lack of enhancement, the cortical tissue demonstrates normal enhancement and is compressed by peripheral nephroblatomatosis rests, the right kidney is affected to a greater degree than the left

3-MRI :*T1 : the nodules demonstrate low signal

intensity foci *T2 : the nodules demonstrate low signal

intensity foci *T1+C : no enhancement

T1+C shows the foci of NB (nephroblastomatosis) were well shown on T1+C, as non-enhancing lesions (yellow arrow), whereas the lesions were not detectable in native T1 and T2

T1+C shows bilateral perilobar non-enhancing lesions (yellow and red arrows) 

Noncontrast (a) and contrast enhanced (b) T1 show a large hypointense cortical mass at the right kidney and multiple smaller foci in both kidneys

6-Mesoblastic Nephroma (Hamartoma) :a) Incidenceb) Radiographic Features

a) Incidence :-Most common solid renal mass in the

neonate, uncommon in children and rare in adults

-The tumor is benign (hamartoma)-It is usually identified within the first 3

months of life with 90% of cases discovered within the 1st year of life , there is a slight male predominance

b) Radiographic Features :-Solid very large intrarenal mass in neonate-Imaging studies shows a large solid

intrarenal mass that typically involves the renal sinus , the mass replaces a large portion of renal parenchyma and may contain cystic , hemorrhagic and necrotic regions , local infiltration of the perinephric tissues is common

Mesoblastic nephroma in a 5-week-old male infant with an in utero renal mass, (a) Longitudinal US scan shows a mass of mixed echotexture replacing the lower pole of the right kidney (arrows), (b) CT scan shows moderate enhancement (arrow)

7-Clear Cell Sarcoma :-Represents 6% of all pediatric renal tumors-Highly malignant with worse prognosis than

Wilms tumor-High propensity for skeletal metastases-Cannot be distinguished from Wilms tumor

by imaging studies alone

Clear cell sarcoma in a 13-month-old girl with an abdominal mass, (a) CT scan shows extensive central necrosis within a mass arising from the right kidney, (b) CT scan obtained at a higher level shows heterogeneous enhancement (arrows) with mass effect and hydronephrosis of adjacent calices (arrowheads)

8-Rhabdoid Tumor of Kidney :a) Incidenceb) Radiographic Features

a) Incidence :-2 % of childhood renal tumors-Poor prognosis and common metastases to

lung , liver and brain-Associated with primary brain tumors of

neuroectodermal origin including medulloblastoma , ependymoma , glioma and PNET

b) Radiographic Features :-Difficult to distinguish from Wilms tumor by

imaging alone , however areas of necrosis or calcification outlining tumor lobules may suggest rhabdoid tumor

Rhabdoid tumor in an 8-month-old boy with hematuria, CT scan shows a left renal mass with heterogeneous enhancement (arrow)

9-Multilocular Cystic Nephroma (MLCN) :a) Incidenceb) Radiographic Features

a) Incidence :-Congenital renal lesion characterized by

large (>10 cm) cystic spaces-It occurs in children ages 2 months to 4

years with 75% male predilection and in adults >40 years of age with 95% female predilection

-In Differential Diagnosis of Pediatric renal masses

b) Radiographic Features :-CT+C shows a well-defined intrarenal

multilocular mass that compresses or displaces the adjacent renal parenchyma , the septations enhance but the cysts do not

-Thick septae , nodules or a large solid component suggest Wilms tumor with cystic degeneration

10-Reninoma (Juxtaglomerular) :-Rare-Small hypovascular masses-Secretion of renin >> hypertension &

hypokalemia

CT+C shows mild enhancement with a small nonenhancing part in the anterior portion (arrow)

Juxtaglomerular cell tumor (reninoma) in a 27-year-old woman with hypertension, (a) Coronal steady-state fast spin-echo T2 shows a small mass (arrowheads) in the central portion of the right kidney, the mass was almost imperceptible during the corticomedullary and nephrographic phases, when it enhanced to the same degree as the renal medulla, (b) On a coronal contrast-enhanced delayed excretory phase image, the mass is homogeneous and demonstrates lower signal intensity than that of the adjacent renal parenchyma, although the imaging findings of a hypovascular central mass are nonspecific, a clinical manifestation of hypertension is helpful, and the possibility of reninoma should be considered

T1+C fat saturated shows a mass (arrow) with low signal intensity with renal parenchyma, suggesting hypovascularity

(ii) Mesenchymal Tumors :-Angiomyolipoma

-Angiomyolipoma (AML) :a) Incidenceb) Radiographic Featuresc) Differential Diagnosis

a) Incidence :-May occur in children-Hamartomas containing : fat , smooth muscle &

blood vessels-Associations :1-T.S. (80% of patients with tuberous sclerosis

have AML)2-Lymphangiomyomatosis

b) Radiographic Features :-Fat containing mass with no calcifications :CT : HypodenseU/S : HyperechoicT1 : HyperintenseCT+C : Heterogeneous enhancement

Multiple AML in T.S.

c) Differential Diagnosis :Fat containing renal masses :1-AML2-RCC :-Invasion of perirenal fat or intratumoral metaplasia

into fatty marrow (in one third of cases of RCC if < 3 cm)

3-Lipoma :-No different on CT to AML

4-Liposarcoma :-Large bulky and peripheral5-Wilms Tumor6-Oncocytoma7-Teratoma :-Very rare-Contains various amounts of fat &

calcification

8-Xathogranulomatous Pyelonephritis :-Replacement of the renal parenchyma by

lipid filled macrophages-Middle aged females with Diabetes-Large or staghorn stone in the P.C. system

with multiple non-enhancing low attenuation masses (fat density)

Xanthogranulomatous pyelonephritis

(iii) Renal Pelvis Tumors :1-Benign Tumors : Inverted Papilloma2-Transitional Cell Carcinoma3-Sqaumous Cell Carcinoma4-Collecting Duct Carcinoma

1-Benign Tumors : Inverted Papilloma -No malignant potential-20% are associated with uroepithelial

malignancies elsewhere , most commonly in bladder

2-Transitional Cell Carcinoma (TCC) :a) Incidenceb) Radiographic Featuresc) Differential Diagnosis

a) Incidence :-Most common tumor of the renal pelvis-More in males

b) Radiographic Features :-IVP, CTU & MRU : irregular filling defect-Typically of soft tissue density (8-30HU) with only mild

enhancement (18-55HU), usually significantly less enhancing than renal parenchyma or renal cell carcinomas

-They are usually centered on the renal pelvis (rather than the renal parenchyma as is the case with RCC) 

TCC of the renal pelvicaliceal system in a 58-year-old man, Llongitudinal (a) and transverse (b) sonograms of the right kidney show separation of renal sinus echoes by a lesion of intermediate echogenicity (arrows)

TCC of the renal pelvicaliceal system in a 63-year-old man with gross hematuria, axial unenhanced (a) and corticomedullary phase (b) CT scans show a mildly enhancing (41-99 HU) soft-tissue mass (arrows) in the upper portion of the left renal pelvis, oblique coronal corticomedullary phase (c) and excretory phase maximum intensity projection (d) CT scans show extension of the soft-tissue mass (arrows) to the upper pole renal calix

c) Differential Diagnosis :-Renal pelvis filling defect 1-TCC2-Non-opaque stone3-Blood clot4-Polyps5-Hypertrophied renal papilla6-Vascular impression7-Inflammation (mycetoma)

3-Sqaumous Cell Carcinoma :-Rare , 5% of renal pelvis tumors and <1%

of all renal tumors

4-Collecting Duct Carcinoma :-Rare

Squamous cell carcinoma, (a, b) Axial contrast material–enhanced CT scans, obtained in the corticomedullary (a) and excretory (b) phases, show a hypoattenuating eccentric solid mass (M) in the posterior aspect of the right kidney. The mass causes slight distortion of the renal contour, in contrast to the preserved contour of the contralateral kidney. Note the tumoral irregularities of the caliceal walls (arrow in b)

Collecting duct carcinoma in 39-year-old woman, (a) oblique conventional radiograph from excretory urography shows smooth convex filling defect and nonvisualization of upper pole calix (arrows), which persisted on other views (not shown), (b) CT+C shows ill-defined low-attenuation lesion located centrally in right kidney (arrowhead), corticomedullary phase of contrast excretion persists in this region (arrows); 1.5-cm upper pole medullary lesion was found at nephrectomy

Collecting duct carcinoma, (a) sonogram of a patient with collecting duct carcinoma shows a uniformly hypoechoic renal medullary tumor (arrows), (b) axial gadolinium-enhanced, fat-saturated, three-dimensional gradient-echo MR image shows a complex cystic mass (black arrows) with a mural nodule (white arrow)

Collecting duct carcinoma

(iv) Secondary Tumors :1-Metastases2-Lymphoma

1-Metastases :-Incidence : 20% of cancer patients at

autopsy-Common primary lesions are lung , breast

and colon cancer and melanoma

Renal metastases from papillary thyroid carcinoma in 34-year-old man. Reconstructed coronal contrast-enhanced CT image reveals 2.5-cm ball-type lesion projecting from lateral aspect of left kidney (black arrow), metastatic nature of the lesion was confirmed after percutaneous biopsy, note liver metastases (white arrow), as well as numerous pulmonary nodules

(a) CT of the abdomen (axial view) demonstrating bilateral renal metastases (arrows), (b) Ultrasound of the right kidney showing a 5.5   6.5-cm metastasis (arrow)

2-Lymphoma :a) Incidenceb) Patterns of Involvementc) Radiographic Features

a) Incidence :-Incidence of renal involvement in lymphoma

is 5% (non-Hodgkin's lymphoma (NHL) > Hodgkin's disease)

b) Patterns of Involvement : Three patterns

1-Direct extension from retroperitoneal disease (common)

2-Hematogenous dissemination (common)3-Primary renal lymphoma (i.e. no other

organ involvements) is rare because kidneys do not have primary lymphatic tissue

c) Radiographic Features :-Patterns :1-Multiple lymphomatous masses (hypoechoic,

hypodense), 50%2-Solitary mass3-Diffuse involvement of one or both kidneys

(infiltrative)4-Perirenal lymphoma-Adenopathy

Large cell lymphoma in a 63-year-old man, sagittal renal US image demonstrates lymphoma with a characteristic hypoechoic appearance in the lower pole of the right kidney (arrow)

Recurrent large cell lymphoma in the right kidney in a 28-year-old man, the patient had undergone successful treatment of a large anterior mediastinal mass 7 months earlier, (a) CT+C obtained at the time of recurrence illustrates the sensitivity of this modality for the detection of very small lesions (arrowheads), (b) CT+C obtained 6 weeks later shows that one of the lesions has increased markedly in size (arrow)

Large cell lymphoma in an 11-year-old boy, the patient presented with a large anterior mediastinal mass and renal lesions, CT+C demonstrates small, hypoattenuating masses bilaterally (arrows), a typical finding in renal lymphoma

Large cell lymphoma in a 73-year-old woman, CT+C shows bilateral renal masses with characteristic homogeneous attenuation, smooth borders, and low contrast enhancement, retroperitoneal adenopathy is also present (A)

Diffuse lymphocytic lymphoma in a 65-year-old woman, CT+C shows a large, homogeneous mass enveloping the retroperitoneum and invading the right kidney, note how flow is maintained in the renal arteries (straight arrows) and left renal vein (curved arrow) despite the massive tumor burden, these findings are characteristic of retroperitoneal lymphoma

Large cell lymphoma in a 51-year-old woman, CT+C shows a large tumor mass invading and displacing the left kidney, the tumor also involves the right side of the retroperitoneum

2-Tumors in Adults :(i) Renal parenchymal tumors :1-Renal Cell Carcinoma (RCC) 2-Adenoma 3-Oncocytoma4-Reninoma(ii) Mesenchymal Tumors :-Angiomyolipoma

(iii) Renal Pelvis Tumors :1-Benign Tumors : Papilloma2-TCC3-Sqaumous Cell Carcinoma4-Collecting Duct Carcinoma(iv) Secondary Tumors :1-Metastases2-Lymphoma

3-Tumors in Pediatrics :(i) Renal parenchymal tumors :1-Wilm’s Tumor2-Nephroblastomatosis3-Mesoblastic Nephroma4-Clear Cell Sarcoma5-Rhabdoid Tumor of Kidney6-Multilocular Cystic Nephroma

7-Renal Cell Carcinoma (RCC) :-Rare -Differentiating features from Wilm’s tumors are :1-Older age at presentation (mean 11-12 years)2-Calcification is more common (25%)3-More homogenous and smaller at the time of diagnosis4-Hematuria is more common5-Association with VHL & TS(ii) Mesenchymal Tumors :-Angiomyolipoma

4-Renal Mass in the Newborn :1-Hydronephrosis :-Unilateral or bilateral-The most common cause of an abdominal mass in the first

6 months of life2-MCDK3-PCKD4-Renal Vein Thrombosis :-Unilateral or bilateral5-Mesoblastic Nephroma6-Nephroblastomosis7-Rhabdoid Tumor8-Ossifying Renal Tumor of the Infancy (ORTI)