RENAL MASSESRENAL MASSES

G.Naga SathishG.Naga Sathish

EVALUATING RENAL EVALUATING RENAL MASSESMASSES

TECHNIQUE AND QUALITYTECHNIQUE AND QUALITY The accurate diagnosis of a renal

mass is dependent on many factors, including the clinical history, the nature of the imaging findings, the experience of the radiologist, and the quality of the examination

CT SCANNINGCT SCANNING 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 postcontrast acquisition.

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

Transverse contrast-enhanced CT scans in a 54-year-old woman with a renal cellcarcinoma. (a) Corticomedullary phase scan shows focal thinning (arrow) of the renal cortex, buta definite renal mass is not identified in this early phase of renal enhancement. (b) Nephrographic phase scan shows a 1.5-cm intrarenal mass (arrow), which was surgically proved to be renal cell carcinoma.

MR IMAGINGMR IMAGING

All sequences are performed during an end-expiratory breath hold, and, for those patients who cannot hold their breath for a sufficient period of time (approximately 20 seconds), 2 L/min oxygen is given via a nasal cannula.

By using cushions, the patients’ arms are elevated anterior to the level of their kidneys to avoid a wraparound artifact in the coronal acquisitions.

In all patients referred for evaluation of a renal mass, MR angiography, MR venography, and MR urography are performed by using an oblique coronal breathhold 3D fat-suppressed T1-weighted spoiled gradient-echo sequence before and at multiple time points

after administration of 19 mL of a gadolinium-based contrast material. The 3D slab should be kept as thin as possible, without excluding any of the structures that need to be evaluated, to maximize through-plane spatial resolution

To evaluate the renal parenchyma and a renal mass, a separate 3D breath-hold fat-suppressed T1-weighted fat-saturated spoiled gradient-echo sequence is performed in the transverse plane before and after contrast material administration.

The postcontrast acquisition is performed between MR venography and MR urography.

For the characterization of renal masses and to determine the presence or absence of enhancement, we recommend an imaging delay of 3–5 minutes.

Transverse fat-suppressed T1-weighted MR images in a 68-year-old man with a complex renal mass.

(a)Unenhanced image shows a hemorrhagic mass (arrows) at the upper pole of the left kidney.

(b)(b) Gadolinium-enhanced image shows enhancement of a thickened wall (arrows), but it is difficult to determine if there is any internal enhancement within the mass because of its heterogeneous signal intensity a. A small portion of enhancing renal parenchyma (arrowhead) is present anterior to the mass.

(c) (c) Subtracted image (gadolinium-enhanced image minus unenhanced image) shows nodular enhancement (large arrow) along the wall of the mass and internal enhancement (small arrows), confirming the diagnosis of a renal cancer.

A papillary renal cell carcinoma was diagnosed at surgical pathologic evaluation.

When asked to specifically evaluate a known renal mass at MR imaging, the imaging planes of the sequences may be modified to best depict the mass.

For masses at the poles of the kidney, the coronal and sagittal planes are advantageous because the relationship of the mass to the kidney is not optimally demonstrated in the transverse plane.

Similarly, the transverse and sagittal planes best depict a mass in the anterior or posterior aspect of the kidney,

and the transverse and coronal planes best depict a mass in the medial or lateral aspect of the kidney.

This approach is most important when evaluating a patient with a solitary kidney that contains a renal neoplasm that is amenable to partial nephrectomy

Differentiating enhancing Differentiating enhancing from non enhancing renal from non enhancing renal

massesmasses Most important criteriaMost important criteria Renal mass enhancement is dependent on multiple factors,

including the amount and rate of the contrast material injection, the imaging delay, and the nature of the tissue within the mass

When there is a question of whether a mass enhances at CT, Hounsfield unit measurements should be obtained and compared on the unenhanced and contrast- enhanced images.

conventional (nonhelical) CT scanners, a difference of 10 HU was suggested as evidence of enhancement

At present, there is no universally agreed upon specific number that can be used as definitive and unequivocal evidence of enhancement within a renal mass, and it has been proposed by many authors that the previously used threshold of 10 HU should be increased to 15–20 HU ,

while others believe that a 10-HU threshold is still valid . A renal mass that enhances 10–20 HU is indeterminate and needs

further evaluation for definitive characterization.

In some cases, use of the gallbladder or an obvious simple renal cyst as an internal reference standard and comparison of the Hounsfield unit measurements of that reference standard (on the unenhanced and contrast- enhanced images) is no unanimously accepted way of determining renal mass enhancement.

MR imaging. image subtraction(gadolinium-enhanced fat-suppressed

T1-weighted image minus unenhanced fat-suppressed T1-weighted image) an easy, reliable, and reproducible method of demonstrating the presence or absence of enhancement within a renal mass

Pit falls of enhancementPit falls of enhancement Larger ROI (region of interest)

measurements can be used in homogeneous solid masses

However, cystic, complex, or necrotic masses require multiple small ROI measurements to be obtained from all portions of the mass, similarly placed on both the unenhanced and contrast-enhanced images

renal cysts on occasion may show artificial apparent enhancement of 10 HU or more (pseudoenhancement) at contrast-enhanced CT, and this may potentially lead to the mischaracterization of a renal cyst as a renal neoplasm.

The phenomenon of pseudoenhancement at CT is secondary to the image reconstruction algorithm used in helical scanners to adjust for beam-hardening effects

Pseudoenhancement most often occurs when the cyst is surrounded by renal tissue during the peak level of renal parenchymal enhancement.

Many of these cysts are small (2 cm) and completely intrarenal.

Pseudoenhancement is relatively easy to suspect when a mass appears as a simple cyst and measures 10 HU or less on the unenhanced CT scan.

Images in a 28-year-old man with a right renal mass. (a) Transverse unenhanced CTscan shows 1.4-cm low-attenuating mass (arrow) that measures 15 HU in the upper pole of the right kidney. (b) On the transverse contrast-enhanced CT scan, renal mass measures 32 HU.Although it could represent a hypovascular neoplasm, this intrarenal mass is small and associated with a dense nephrogram, and pseudoenhancement of a renal cyst was suspected. (c) Coronal T2-weighted MR image shows the mass to be uniformly hyperintense,suggesting a simple cyst. (d) Transverse subtracted MR image (gadolinium-enhanced fat-suppressedT1-weighted image minus unenhanced fat-suppressed T1-weighted image) shows noenhancement within the mass, confirming the diagnosis of a simple cyst

Differentiating surgical Differentiating surgical from non surgical renal from non surgical renal

massesmasses In most cases, it is possible to preoperatively differentiate

those renal masses that require surgery (renal cell carcinoma, invasive transitional cell carcinoma, and oncocytoma) from those that do not.

Renal cell carcinoma and oncocytoma are indistinguishable from each other at imaging.

However, angiomyolipoma, lymphoma, metastatic disease, renal anomalies, and other pseudotumors can all mimic renal cell carcinoma.

Frequently it is possible to make this differentiation by using the imaging findings alone, but often the clinical history can be very important in making the correct diagnosis.

In fact, before making a diagnosis of renal cell carcinoma, one should be satisfied that none of these possible mimickers of renal cell carcinoma are potentially present

The differentiation of an angiomyolipoma from a renal cell carcinoma is important because, in most cases (excluding very large lesions or those that are bleeding), angiomyolipomas do not need to be surgically removed.

The diagnosis of an angiomyolipoma is made by demonstrating fat within a solid renal mass

Transverse CT scans in a 45-year-old woman with a renal mass incidentally found onan abdominal CT scan. (a) Contrast-enhanced scan shows a 1.8-cm enhancing mass in the rightkidney. The lesion was thought to represent a renal cell carcinoma. However, because of arelatively low-attenuating region (arrow) in the central portion of the mass (b) Unenhanced scan shows a minimal amount of fat (arrow) (30 HU),diagnostic of an angiomyolipoma. The small amount of fat within this mass is obscured on a.Also, the mass is slightly higher in attenuation than the adjacent renal parenchyma, a finding typical of the myomatous component of the angiomyolipoma

A small number of angiomyolipomas (hamartomas) do not contain macroscopic fat (angiomyomas), and the imaging differentiation from a renal neoplasm is impossible.

These lesions often have a higher attenuation than that of renal tissue (on the unenhanced CT scan) or may demonstrate homogeneous and prolonged enhancement ,

but these findings are not specific enough to make a confident diagnosis of a non–fat-containing hamartoma.

The term “minimal fat” angiomyolipoma has been used in the literature to describe angiomyolipomas with microscopic fat and without demonstrable macroscopic fat

Angiomyolipomas rarely contain calcification and, therefore, a diagnosis of angiomyolipoma should not be made if a lesion contains fat and calcium.

In such cases, a renal cell carcinoma must be considered likely

it is also possible that a large renal cell carcinoma may engulf a small portion of fat in the renal sinus or perinephric fat, or even a small adjacent angiomyolipoma, giving the appearance of a larger angiomyolipoma containing a small amount of fat.

It may not be possible to distinguish these types of masses from each other.

Infiltrating renal massesInfiltrating renal masses

Infiltrating neoplasms lymphoma, inva-sive transitional cell carcinoma, metastatic disease (particularly from lung cancer), and renal cell carcinoma (especially the sarcomatoid subtype) .

These malignancies infiltrate into the renal parenchyma, which results in a region of diminished nephrogram with indistinct margins.

Lymphoma can have a variable appearance and may on occasion resemble renal cell carcinoma.

Most frequently, it manifests as bilateral solid renal masses, and in a patient with systemic lymphoma the proper diagnosis is not difficult.

a renal mass that does not have the imaging characteristics of lymphoma, biopsy of the mass is indicated prior to systemic therapy

Transverse gadolinium-enhanced fat-suppressed T1-weighted MR image in an 84-year-old woman with a renal mass shows a solid enhancing mass (longarrows) in the left renal sinus, infiltrating into the kidney. Large left periaortic lymph nodes (short arrow) are also present. Results at biopsy of the lymphadenopathy confirmed lymphoma

Transitional cell carcinoma of the kidney is usually diagnosed by detecting a filling defect in the collecting system that enhances on a CT or MR image.

However, a small percentage of transitional cell carcinomas are anaplastic and infiltrate into the renal sinus and kidney parenchyma).

These masses are very aggressive and have a poor prognosis, often manifesting with lymph node metastases.

The differentiation from other infiltrative lesions (which may also involve the renal sinus) is critical because

transitional cell carcinoma- nephroureterectomy, lymphoma systemic -chemotherapy infiltrative renal cell carcinoma -nephrectomy. Biopsy of infiltrative transitional cell carcinoma should

be avoided if possible because of the propensity for seeding

Transverse contrast-enhanced CT scan in a 73-year-old man with transitional cell carcinoma in the right kidney shows a tumor that arises from the right renal collecting system and infiltrates into the renal sinus and kidney parenchyma. Findings are consistent with invasive transitional cell carcinoma. Note large lymph node metastases (arrow) posterior to the inferior vena cava.

Metastatic disease to the kidney typically manifests as multiple bilateral renal masses, often associated with metastatic disease to other organs

Pseudo tumors and renal Pseudo tumors and renal mass mimikersmass mimikers

This group includes congenital anomalies and inflammatory masses

A renal pseudo tumor represents normal renal tissue that may mimic a renal neoplasm.

Congenital pseudotumors are normal variants which include prominent renal columns of Bertin, renal dysmorphism, and dromedary humps,

while acquired pseudotumors represent hypertrophied normal renal parenchyma assuming a tumorlike appearance adjacent to parenchymal scarring

it is advantage of the corticomedullary phase to demonstrate the normal corticomedullary differentiation in the suspected “mass.”

Inflammatory masses, including focal pyelonephritis and renal abscess, may also mimic the appearance of a renal neoplasm.

However, with the appropriate clinical history the correct diagnosis usually becomes apparent.

the differentiation of a cystic renal neoplasm from a subacute or chronic renal abscess can be difficult when the typical clinical findings of infection are not present.

If a remote history of fever, leukocytosis, or urinary tract infection is obtained, needle aspiration should be performed, and if pus is recovered, percutaneous drainage can be instituted.

However, if blood or necrotic debris is recovered, surgical removal is indicated

Transverse contrast-enhanced CT scans in a 63-year-old man with a left renal pseudotumor.(a) Nephrographic phase scan shows a focal “mass” (large arrow) adjacent to a scar (smallarrow) in the left kidney. The left kidney is smaller than the right kidney, and the mass enhances identically to the renal parenchyma. (b) Corticomedullary phase scan shows corticomedullary differentiation in the renal “mass,” diagnostic of localized hypertrophy of normal renal parenchyma

Cystic renal massesCystic renal masses complex cystic renal masses may be

initially detected with US they cannot be accurately characterized

by using US alone. Therefore, we do not use US in the

evaluation of cystic renal masses, with the exception of proving that a renal mass is a simple cyst (such as in a case of suspected CT pseudoenhancement).

On the other hand, MR imaging does have a role in evaluating cystic renal masses

Bosniak ClassificationBosniak Classification

Management of renal cystic Management of renal cystic disease according to disease according to

Bosniak Classification Bosniak Classification

category Management

I , II Ignore & No need for follow up

II F Follow up

III , IV Surgical excision

Autosomal dominant polycystic kidney disease:Autosomal dominant polycystic kidney disease: Heridiatry Heridiatry Htn commonHtn common Aortic aneurysm, dissection, and valvular Aortic aneurysm, dissection, and valvular

heart disease more commonheart disease more common Average age of onset of renal failure 6Average age of onset of renal failure 6thth to 7 to 7thth

decadedecade Flank pain, hematuria uti , nephrolithiasisFlank pain, hematuria uti , nephrolithiasis Detection of cysts in other organs are useful Detection of cysts in other organs are useful

clue in diagnosis.clue in diagnosis. Bilateral involvement commonBilateral involvement common Calcf commonCalcf common

Aquired cystic disease of kidneyAquired cystic disease of kidney Common in pts with hemo or peritoneal Common in pts with hemo or peritoneal

dialysisdialysis 80 %reported after 380 %reported after 3rdrd year of dialysis year of dialysis Hyperplasia of tubular epithelium Hyperplasia of tubular epithelium

resulting in blokade and dilatation of resulting in blokade and dilatation of nephrons leading to cyst formationnephrons leading to cyst formation

RCC 40 times more common in pts on RCC 40 times more common in pts on dialysisdialysis

benign renal massesbenign renal masses

The 2004 World Health Organization (WHO) classification schemata categorizes benign renal neoplasms on the basis of histogenesis (cell of origin) and histopathology .

Renal neoplasms are thus classified into renal cell, metanephric, mesenchymal, and mixed epithelial and mesenchymal tumors.

Renal cell neoplasmRenal cell neoplasm Oncocytoma:Oncocytoma: Peak age of incidence 70 yrsPeak age of incidence 70 yrs Males > femalesMales > females Oncocytomas typically appear as solitary,

well-demarcated, unencapsulated, fairly homogeneous renal cortical tumors.

Bilateral, multicentric oncocytomas are seen in hereditary syndromes of renal oncocytosis and Birt-Hogg-Dubé syndrome (in association with the chromophobe subtype and other RCC subtypes.

A characteristic central stellate fibrotic scar (more often seen with large tumors) is seen in up to 33% of tumors

Hemorrhage may be found in up to 20% of cases.

A spoke-wheel pattern of feeding arteries associated with a homogeneous nephrogram is a characteristic finding on catheter angiography .

However, oncocytomas are indistinguishable from renal cell carcinomas on the basis of imaging findings alone.

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 mas (arrow) with hyperintense central scar (S).B, Axial fat-saturated, gadolinium-enhanced T1-weighted 3D gradient-refocused echo image shows right kidney mass (arrow) with hypointense central scar (S)

Papillary adenoma:Papillary adenoma: Most common epithelial neoplasmsMost common epithelial neoplasms Commonly found in pts with aquired renal Commonly found in pts with aquired renal

cystic disease & pts undergoing long term cystic disease & pts undergoing long term hemodialysishemodialysis

papillary adenomas measure 5 mm or less . They are usually subcapsular and solitary. Adenomas are histologically characterized

by papillary or tubular cytoarchitecture and frequent psammoma bodies

Mesenchymal neoplasmMesenchymal neoplasm

Angiomyolipoma:Angiomyolipoma: Most common benign mesenchymal Most common benign mesenchymal

neoplasmneoplasm Composed of variable proportions of blood

vessels, smooth muscle, and adipose tissue .

Renal AMLs consist of two distinct histologic subtypes, classic and monotypic epithelioid.

Epithelioid AMLs typically do not show macroscopic fat and appear as soft-tissue masses and are thus indistinguishable from other solid renal masses.

This rare subtype of AML is potentially malignant and may exhibit aggressive biology, including recurrence, metastasis, and death

Classic AML may occur either sporadically or in association with tuberous sclerosis complex (TSC).

Sporadic renal AMLs show a 4:1 female preponderance and are more likely to be solitary and symptomatic

Large tumor size (> 4 cm) and diameter of the intralesional aneurysms (> 5 mm) correlate directly with tumor-related hemorrhage in AMLs

On sonography, small AMLs appear uniformly hyperechoic without a hypoechoic rim or intralesional cysts .

Large AMLs appear as variegated masses with macroscopic fat, hemorrhage, and hypervascular soft-tissue components

The presence of macroscopic fat on CT or MRI is characteristic of AMLs.

Loss of signal intensity on frequency-selective fat-suppressed MRI definitively identifies macroscopic fat .

However, a multitude of renal neoplasms, including RCC, oncocytoma, lipoma, and liposarcoma, may show either intratumoral fat or engulfed perirenal fat

Recent studies indicate that in contradistinction to RCCs, AMLs with minimal fat show uniform, prolonged contrast enhancement and a higher signal intensity index on double-echo, chemical shift FLASH MRI

43-year-old woman with hematuria. Transvers sonogram shows uniformly echogenic mass (arrows)in upper pole of left kidney (K) that was proven to be angiomyolipoma

58-year-old woman with angiomyolipoma of kidney. Sagittal contrast-enhanced CT scan shows exophytic renal mass (arrows) with foci of macroscopic fat (arrowhead).

38-year-old woman with documented tuberous sclerosis complex and renal angiomyolipomas.A, Axial in-phase T1-weighted 2D gradient-refocused echo MR image shows bilateral multicentric renal masse that have increased signal intensity (arrows).B, Axial fat-saturated T2-weighted 2D gradient-refocused echo MR image shows marked drop in signal intensity of masses (arrows)

Hemangioma:Hemangioma: rare benign mesenchymal neoplasm that

consists of multiple endothelium-lined, blood-filled vascular spaces .

It commonly affects young adults with no specific sex predilection.

Recurrent episodes of hematuria and renal colic are typical presenting symptoms;

may be associated with systemic syndromes such as Sturge-Weber and Klippel-Trénaunay and with systemic angiomatosis .

Cavernous hemangiomas are more common than the capillary variants

Hemangioma frequently arises from the renal pyramids or the pelvis.

Hemangiomas show variable echogenicity on sonography

hyperintensity on T2-weighted MRI Contrast-enhanced CT and MRI of renal

hemangiomas may show early, intense enhancement .

Persistent contrast enhancement on delayed images is fairly characteristic of renal hemangiomas

60-year-old man with hematuria and histologically proven hemangioma.A, Axial fat-saturated T2-weighted 2D gradient-refocused echo MR image shows hyperintense left kidney mass in renal sinus (arrow).B, Axial fat-saturated gadolinium-enhanced T1-weighted 3D gradient-refocused echo MR image shows contrast enhancement of left renal sinus mass (arrows).

Lymphangioma:Lymphangioma: Rare benign cystic tumor Rare benign cystic tumor Often arises from Often arises from peri pelvic region peri pelvic region or renal or renal

sinus.sinus. Renal lymphangioma may occur either as an

isolated finding or in association with perinephric or systemic lymphangiomatosis.

It may appear as a localized process or a diffusely cystic lesion.

typically appears as a well-demarcated, uni- or multilocular cystic neoplasm that most commonly arises from the renal sinus region or in the perinephric space

47-year-old man with bilateral multiple renal sinuses and perinephric lymphangiomatosis.Unenhanced axial CT scan shows multicentric cystic masses in renal sinus and perinephric spaces (arrows).

LEIOMYOMA:LEIOMYOMA: Renal leiomyomas are rare benign smooth muscle neoplasms

that mostly occur in adults as incidental findings . Renal capsule is the most common target site of leiomyomas; rarely, leiomyomas originate from the renal pelvis or cortex. Leiomyomas of the kidney commonly appear as well-

circumscribed, homogeneous, exophytic solid masses that show uniform enhancement on contrast-enhanced CT

Larger tumors are heterogeneous because of hemorrhage and cystic or myxoid degeneration

Calcification is uncommon. However, the CT findings of leiomyomas of the kidney may be

variable and may include cystic, complex cystic–solid, or purely solid morphology [44].

Renal leiomyomas may show hypervascularity on catheter angiography because they are predominantly supplied by capsular vessels

43-year-old woman with renal leiomyoma of capsular origin. Axial contrast-enhanced CT scan shows large, fairly homogeneous exophytic mass(arrows) arising from left kidney (K).

JUXTAGLOMERULAR CELL NEOPLASM (RENINOMA)

Juxtaglomerular cell (JGC) neoplasm is an extremely rare, benign renal neoplasm of myoendocrine cell origin .

The peak age of incidence is in the second and third decades and a 2:1 female preponderance is seen.

JGC neoplasm is clinically characterized by a triad of findings: poorly controlled hypertension, hypokalemia, and high plasma renin activity

JGC neoplasm typically appears as a unilateral, well-circumscribed, cortical tumor that usually measures less than 3 cm.

Despite profuse vascularity, JGC neoplasms appear hypovascular on contrastenhanced CT and MRI, possibly because of renin-induced vasoconstriction.

JGC neoplasms may show delayed contrast enhancement. Imaging findings of JGC neoplasms are nonspecific and

indistinguishable from other solid renal neoplasms

23-year-old woman with hypertensio refractory to standard treatment. Axial unenhanced CT scan shows large, expansile right renal mass (arrow) that was histologically proven to be juxtaglomerular cell neoplasm (reninoma). K = kidney, M = mass

Mixed epithelial & Mixed epithelial & mesenchymal neoplasmmesenchymal neoplasm

comprise two histologically distinct entities: mixed epithelial and stromal tumors and cystic nephromas.

Mixed Epithelial and Stromal Tumor Mixed epithelial and stromal tumors occur almost

exclusively in perimenopausal women (6:1 female preponderance);

most patients are receiving estrogen therapy . Twenty five percent of the tumors present as

incidental findings; most patients manifest nonspecific symptoms of flank

pain and hematuria.

On imaging, mixed epithelial and stromal tumors typically appear as expansile, complex, cystic–solid masses with heterogeneous and delayed enhancement.

The proportion of cystic and solid constituents varies in any given case.

The stromal component of the tumor is thought to be responsible for the hypointense signal on T2-weighted MRI with delayed contrast enhancement

Large mixed epithelial and stromal tumors may herniate into the renal pelvis.

The tumors typically show benign biologic behavior without recurrence or metastasis;

however, aggressive mixed epithelial and stromal tumors with sarcomatous transformation of the stromal component have been described

40-year-old woman with histologically proven mixed epithelial and stromal tumor of kidney. Axial contrast-enhanced CT scan shows large complex cystic left kidney (K) mass (arrows) with septations and solid components.

Cystic Nephroma Cystic nephroma is a benign cystic neoplasm that affects

predominantly middle-aged, perimenopausal women. Adult-onset cystic nephroma is histogenetically and

morphologically different from pediatric cystic nephroma Morphologically, cystic nephromas are composed of

encapsulated, noncommunicating cysts with thin septations.

Septa show no enhancement. Calcft of septa may be seen cystic nephromas are characterized by the absence of a

solid component or necrosis. Cystic nephroma appears as a well-demarcated, solitary,

multilocular cystic lesion with thin septations. The cystic mass may protrude into the renal pelvis and

cause hemorrhage or urinary obstruction

14—50-year-old woman with cystic nephroma.A, Coronal contrast-enhanced CT scan shows lobulated, expansile, cystic mass (M) in left kidney (arrow) that compresses calyces (C).

conclusionconclusion leiomyomas originate from the renalcapsule,

hemangiomas typically arise from the renal sinus.

Approximately one third of large oncocytomas typically show a central stellate scar.

Cystic nephromas show septated cysts, macroscopic fat predominates in most

angiomyolipomas. metanephric adenomas are commonly solid. Mixed epithelial and stromal tumors consist of

solid areas and cysts that may herniate into the renal pelvis

Malignant lesionsMalignant lesions Renal cell carcinoma:Renal cell carcinoma:

Pathologically adenocarcinomaPathologically adenocarcinoma Common in adultsCommon in adults MalesMales Associated with cigarrette smokingAssociated with cigarrette smoking Symptoms: pain hematuria, wt loss and abdominal Symptoms: pain hematuria, wt loss and abdominal

distension.distension. Imaging: focal renal mass centered in renal cortex.Imaging: focal renal mass centered in renal cortex. Mass distorts the marginsMass distorts the margins Calcifications 25%. Common in larger lesions than Calcifications 25%. Common in larger lesions than

smallsmall Calcftns: punctate, amorphous, linear or peripheralCalcftns: punctate, amorphous, linear or peripheral Often renal vein invasion. Thrombus may extend into Often renal vein invasion. Thrombus may extend into

ivc.ivc. Thrombus may show arterial enhancement.Thrombus may show arterial enhancement.

Do not usually metastasize when less than Do not usually metastasize when less than 3 cms.3 cms.

Mets: to liver, lung bone and nodes.Mets: to liver, lung bone and nodes. Liver mets often hypervascular.Liver mets often hypervascular. Mets to retro peritoneal space has poor Mets to retro peritoneal space has poor

prognosisprognosis MRI: typically mild hypointense to renal MRI: typically mild hypointense to renal

cortex on T1 and mildly high T2 signal.cortex on T1 and mildly high T2 signal. Lesion show enhancement.Lesion show enhancement. Most RCC’S have Most RCC’S have a hypointense pseudo a hypointense pseudo

capsule capsule at the periphery of tumor.at the periphery of tumor. Mri sensitive for IVC thrombosis.Mri sensitive for IVC thrombosis.

Staging: Staging: robsons classf:robsons classf: Involvement of gerotas fascia is a negitive Involvement of gerotas fascia is a negitive

clinical indicator.clinical indicator. Stage 1 : limited to renal capsuleStage 1 : limited to renal capsule Stage 2: gerotas fasciaStage 2: gerotas fascia Stage3: thickening of structures in peri Stage3: thickening of structures in peri

nephric space. Renal vein invasions,ivc, nephric space. Renal vein invasions,ivc, adrenal mets or regional adenopathyadrenal mets or regional adenopathy

4:distant mets or spread to adjacent 4:distant mets or spread to adjacent organs other than adrenalsorgans other than adrenals

Drawing of the anatomy of the retroperitoneal spaces at the level of the kidneys. The anterior pararenal space (APRS) is located between the parietal peritoneum (PP) and the anterior renal fascia (ARF) and contains the pancreas (Pan), the ascending colon (AC), and the descending colon (DC). The posterior pararenal space (PPRS) is located between the posterior renal fascia (PRF) and the transversalis fascia (TF). The perirenal space (PRS) is located between the anterior renal fascia and the posterior renal fascia.

Transitional cell Transitional cell carcinomacarcinoma

Urothelial tumors are less common in Urothelial tumors are less common in upper urinary tract.than RCCupper urinary tract.than RCC

Second most renal neoplasm in adultsSecond most renal neoplasm in adults Risk factors: nsaids, tobacco etc.Risk factors: nsaids, tobacco etc. Common in malesCommon in males Increased in horse shoe kidneyIncreased in horse shoe kidney Present with hematuriaPresent with hematuria Initial detection done on IVPInitial detection done on IVP Ocasionally usg may detect a collecting Ocasionally usg may detect a collecting

system lesion in calyces or renal pelvis.system lesion in calyces or renal pelvis.

3 general ct imaging appearance:3 general ct imaging appearance: Smal hypodense lesion in collecting systemSmal hypodense lesion in collecting system Soft attenuation value HU<40 less than calculi and Soft attenuation value HU<40 less than calculi and

clot.clot. Enhance 10-50 huEnhance 10-50 hu Enhancemnt less than surrounding renal Enhancemnt less than surrounding renal

parenchymaparenchyma Stippled calcificationsStippled calcifications Necrosis in large lesion uncommonNecrosis in large lesion uncommon Do not involve renal veinDo not involve renal vein May present as infiltrative renal massMay present as infiltrative renal mass Mass originates from centre of kidneyMass originates from centre of kidney Renal contour usually not disrupted unlike RCC Renal contour usually not disrupted unlike RCC

(BEAN VS BALL)(BEAN VS BALL)

Thickening of collecting system urothelium or Thickening of collecting system urothelium or uretreral wall.uretreral wall.

Thickening may be symmetric or eccentric.Thickening may be symmetric or eccentric. Expansion of collecting system above the areaExpansion of collecting system above the area Tumor insitu and limited to sub mucosa have Tumor insitu and limited to sub mucosa have

best prognosis.best prognosis. Stage2: invasion beyond subepithelial tissueStage2: invasion beyond subepithelial tissue Stage 3: muscularis, invasion of renal Stage 3: muscularis, invasion of renal

parenchyma,or peri pelvic/periureteral fat.parenchyma,or peri pelvic/periureteral fat. Stage4: nodal involvement., organs bone and Stage4: nodal involvement., organs bone and

lungs.lungs.

lymphomalymphoma

Usually part of systemic diseaseUsually part of systemic disease Renal involvement is usually a symptamaticRenal involvement is usually a symptamatic Non hodgkins more common than hodgkinsNon hodgkins more common than hodgkins CT more sensitive than USGCT more sensitive than USG 4 common presentations4 common presentations 1: Multifocal renal lesions usually bilateral1: Multifocal renal lesions usually bilateral Enhancement less than surrounding renal Enhancement less than surrounding renal

parenchymaparenchyma Calcifications rare unless there is therapyCalcifications rare unless there is therapy

2:2: invasion of kidney by renal massinvasion of kidney by renal mass Does not involve renal vein / IVCDoes not involve renal vein / IVC 33: perinephric rind of soft tissue around : perinephric rind of soft tissue around

kidney without a focal parenchymal lesion.kidney without a focal parenchymal lesion.

4:diffuse infiltrative involvement of kidney 4:diffuse infiltrative involvement of kidney Less common.Less common. Predominant involvement of medulla with Predominant involvement of medulla with

relative sparing of cortical margins.relative sparing of cortical margins. Usually involves renal hilum may encase Usually involves renal hilum may encase

renal vessels resulting in decreased renal renal vessels resulting in decreased renal enhancement.enhancement.

MRI features similar to CTMRI features similar to CT Hypo to renal parencyma on T1 and Hypo to renal parencyma on T1 and

slightly hyper on T2slightly hyper on T2 Mild heterogenous enhancement less than Mild heterogenous enhancement less than

renal parenchyma on T1 gadorenal parenchyma on T1 gado

Primary renal lymphoma is a form of NHL Primary renal lymphoma is a form of NHL arisng directly from renal parenchymaarisng directly from renal parenchyma

Extremely rare as normal kidney is free Extremely rare as normal kidney is free of lymphatic tissueof lymphatic tissue

metastasesmetastases Excluding lymphoma & leukemia Excluding lymphoma & leukemia most most

common primary sites: lung , colon, common primary sites: lung , colon, breast,melanoma, testicular & ovarian breast,melanoma, testicular & ovarian malignancy.malignancy.

Usually asyptamatic rarely hematuriaUsually asyptamatic rarely hematuria Ct very sensitiveCt very sensitive Multi focal renal masses, usually bilateralMulti focal renal masses, usually bilateral Hypodense 20-40 huHypodense 20-40 hu Do not demonstrate hyper enhancement 5-15 Do not demonstrate hyper enhancement 5-15

huhu Large mets may be from lung , colon or breastLarge mets may be from lung , colon or breast Colon mets disrupts renal cortical marginColon mets disrupts renal cortical margin

Peri nephric space involvemnt by Peri nephric space involvemnt by mets seen in melanoma and lung metsmets seen in melanoma and lung mets

Hemorrhagic mets: melanomaHemorrhagic mets: melanoma May also be seen in May also be seen in

pheocromocytoma leiomyosarcoma.pheocromocytoma leiomyosarcoma.

Difference from RCC:Difference from RCC:Usually bilateral, less necrosis, no renal Usually bilateral, less necrosis, no renal

vien involvemnt/ thrombosisvien involvemnt/ thrombosis

sarcomasarcoma

Common in pts > 40yrsCommon in pts > 40yrs Hematuria, abd distension , pain wt lossHematuria, abd distension , pain wt loss Leomyosarcoma most commonLeomyosarcoma most common May be seen in perinephric spaceMay be seen in perinephric space Rx: surgical resection…poor prognosisRx: surgical resection…poor prognosis Ct: heterogenous lesions… fibrous Ct: heterogenous lesions… fibrous

component delayed enhancement spindle component delayed enhancement spindle cell component early enhancement.cell component early enhancement.

MR: low on T1 and mixed on T2MR: low on T1 and mixed on T2

Liposarcoma:Liposarcoma: Usually from capsuleUsually from capsule Present with mass , pain , wt loss without Present with mass , pain , wt loss without

hematuriahematuria Ct: retroperitoneal mass with macroscopic fat.Ct: retroperitoneal mass with macroscopic fat. Tumour capsule may be present, may displace Tumour capsule may be present, may displace

kidney.kidney. Hypovascular massHypovascular mass Parenchymal invasion not typical.Parenchymal invasion not typical.

Unlike AML this lesion is relatively avascular Unlike AML this lesion is relatively avascular and without enlarged vessels.and without enlarged vessels.

Wilms tumorWilms tumor Children 3-4 yrsChildren 3-4 yrs Pesents as palpable abd massPesents as palpable abd mass May be associated with WAGR (wilms,aniridia, May be associated with WAGR (wilms,aniridia,

gu abnormality and retardation)gu abnormality and retardation) Drash(wilms, congenital nephropathy,pseudo Drash(wilms, congenital nephropathy,pseudo

hermaproditism)hermaproditism) Ct: focal solid mass with appearance similar to Ct: focal solid mass with appearance similar to

rccrcc Enhances heterogenouslyEnhances heterogenously Cystic changes and necrosis may be seenCystic changes and necrosis may be seen Perinephric extension and adenopathy may be Perinephric extension and adenopathy may be

seenseen Vascular invasion commonVascular invasion common Calcfnts are rareCalcfnts are rare

Wilms' tumor vs Wilms' tumor vs NeuroblastomaNeuroblastoma

Wilms'Wilms' <10% are calcified; <10% are calcified;

more often a more often a curvilinear patterncurvilinear pattern

Occasional local para-Occasional local para-aortic adenopathy (less aortic adenopathy (less common than with common than with neuroblastoma)neuroblastoma)

IVC invasion has high IVC invasion has high positive predictive positive predictive valuevalue

Mets to lungs commonMets to lungs common

NeuroblastomaNeuroblastoma Often calcified; scattered Often calcified; scattered

pattern throughout masspattern throughout mass Large regional adenopathyLarge regional adenopathy High predictive value: High predictive value:

encasement of great vessels, encasement of great vessels, spinal canal invasion, spinal canal invasion, paravertebral massparavertebral mass

Moderate predictive value: Moderate predictive value: extension across midline, extension across midline, displacement of great vesselsdisplacement of great vessels

Mets to liver, bone commonMets to liver, bone common Elevated urine Elevated urine

catecholaminescatecholamines

Wilms vs Neuroblastoma Wilms vs Neuroblastoma Vascular invasion common, does not Vascular invasion common, does not

encase aorta, calcfts rare, mets encase aorta, calcfts rare, mets common to lungs in wilmscommon to lungs in wilms

MR: mild hypo on T1 high T2MR: mild hypo on T1 high T2 Heterogenous enhancementHeterogenous enhancement Vein and IVC well seen on MR than CTVein and IVC well seen on MR than CT