KUB:Benign neoplasms

Dr arif khan s

INTRODUCTION

URINARY SYSTEM

KIDNEYS

URETER

BLADDER

RENAL NEOPLASM

Adult

Paediatric

WHO classification categorises neoplasms on basis of cell of origin and histopathology.

Most renal tumors arise from the parenchyma, refered to as renal cell tumors

Small number from mesenchyme and collecting system.

WHO 2006 (hiedelberg classfication)Renal cell tumours

Malignant • Clear cell renal cell carcinoma

• Multilocular clear cell renal cell carcinoma

• Papillary renal cell carcinoma

• Chromophobe renal cell carcinoma

• Carcinoma of the collecting ducts of Bellini

• Renal medullary carcinoma

• Xp11 translocation carcinomas

• Carcinoma associated with neuroblastoma

• Mucinous tubular and spindle cell carcinoma

• Renal cell carcinoma unclassified

Benign Papillary adenoma Oncocytoma

Mesenchymal tumors classification(W.H.O ………contd)

Metanephric tumors • Metanephric adenoma

• Metanephric adenofibroma

• Metanephric stromal tumors

Mixed mesenchymal and epithelial tumors • Cystic nephroma

• Mixed epithelial and stromal tumor

• Synovial sarcoma

Nephroblastic tumors • Nephrogenic rests

• Nephroblastoma

• Cystic partially differentiated nephroblastoma

Neuroendocrine tumors

• Carcinoid

• Neuroendocrine carcinoma

• Primitive neuroectodermal tumor

• Neuroblastoma

• Pheochromocytoma

Other tumors

• Mesenchymal tumors

• Hematopoietic and lymphoid tumors

• Germ cell tumors

• Metastatic tumors

Balls v/s beans concept By Harman and ros

BALL TYPE

Most by expansion appears as exophytic balls from the poles

Eg: cysts, renal cell carcinomas, angiomyolipoma, metastasis, oncocytoma

These masses are shaped similarly to spheres or balls and they displace and compress, rather that invade normal structure

BEAN TYPE

grow along the latticework of normal renal parenchyma

Infiltrating lesions swell the area of involved parenchyma,

do not deform the shape. The kidney retains the ‘bean’ shape.

These are difficult to detect radiologically since little mass effect

is associated.

Eg;

transitional cell carcinoma, squamous cell, lymphoma,

renal medullary carcinoma

Imaging modalities

IVU Excretory urography lacks specificity for accurately

characterizing a lesion.

Expansile masses cause contour abnormalities, calcyeal splaying, stretching and draping.

Infiltrating renal mass produce little parenchymal mass effect and maybe seen as a filling defect in the collecting system.

Ultrasound

Ultrasound is very useful for detection of renal masses and characterizing them as solid or cystic.

Ultrasound may also be useful when CT

pseudoenhancement is noted, leading to a simple renal cyst being mischaracterized as solid mass.

Color Doppler sonography can evaluate renal vein and IVC for presence of thrombus

The vascular flow within a renal mass, identified by color and power Doppler is strongly associated with clear cell carcinoma.

Peripheral or mixed peripheral and penetrating patterns are seen.

CT CT is accurate in detection, characterization and staging of renal

masses. MDCT allows fast, multiphase and high resolution imaging

For characterization of a renal mass, the examination is to performed before and after administration of IV contrast

the different phases of renal enhancement arterial (15-20sec delay) corticomedullary (35-80 sec), nephrographic (85-180 sec) and excretory (3 min or more) need to be evaluated.

The nephrographic phase is ideal for detection of masses as there is maximal andhomogenous parenchymal enhancement

In corticomedullary phase, small renal masses may be indistinguishable from renal medulla.

excretory phase, masses may be same attenuation as the parenchyma which has de-enhanced.

Cortico-medullary phase may help in characterizing pseudo-tumors such as hypertrophy of column of Bertin

Careful attention is to be given to enhancement that is identified as unequivocal and not due to pseudoenhancement which is elevated HU measurement of cyst due to image reconstruction algorithm

It may be useful to adopt gallbladder or a simple cyst (when present) as internal reference standard for Hounsfield unit measurement

An increase in attenuation of 10 HU or more in a lesion measuring at least 2 cm in diameter indicates enhancement

As enhancement is transient, washout of contrast is also useful.

If an area of enhancement decreases subjectively or quantitatively (at least 10 HU), neoplasm is suspected. This is called “de enhancement”.

CT urography is beginning to replace IVU as the imaging examination of choice to detect upper urinary tract tumors.

MRI especially useful in patients in whom iodinated contrast is contraindicated.

PROTOCOL Coronal HASTE for planning ,

axial T2-weighted gradient and spin echo with fat suppression,

axial dual echo in phase and opposed phase gradient echo T1 images, and

3D fat suppressed GRE T1 images before and after iv contrast

followed by a coronal 3D fast gradient echo sequence with fat suppression after the dynamic series to display renal venous anatomy and IVC,

MRimaging is valuable for distinct renal lesions.

On MR imaging, hemorrhagic cysts have high signal on T1WI.

A homogeneous hyperintense lesion on T2 with a thin wall and no enhancement is a renal simple cyst.

All 3 phases of renal excretion are obtained after contrast and subtraction images may be obtained to determine, percentage of enhancement

In and opposed phase images help in detecting intratumoral fat.

MR urogram is indicated in patients with suspected collecting system disease

Oncocytoma

solid non-fat containing renal mass,

Arising from proximal tubule with many characteristics of RCCs

Most oncocytomas are asymptomatic (80%), but few may present with hematuria pain or mass

The peak age of incidence is in the seventh decade with a male pre-ponderance.

IMAGING

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

Bilateral multiple oncocytomas are seen in hereditary syndromes of renal oncocytosis

USG may show a central stellate scar within a solid hematogenous mass.

Generally tend be large well demarcated tumours at presentation.

Non contrast

if less than 3 cm - homogenous attenuation 

if more than 3 cm - heterogenous attenuation

perinephric fat-stranding may be present  due to oedema

calcification may be present

Post contrast  small tumours may enhance

homogeneously, but usually enhancement is heterogenous and the mass is larger

central stellate non-enhancing scar is seen in approximately a third of cases  4

renal vein thrombosis may be present, but tumour thrombus is absent.

Post contrast: Cart wheel Enhancement homogenously enhancing

The presence of a central scar, absence of calcification or necrosis and haemorrhage suggests the diagnosis

Surgery is usually performed for these and HPE is indicated to confirm both.

MRI: T1W – Hypo to iso intense ; T2W hyperintense,

The central scar, if present is hypointense on T2

Post contrast show heterogenous enhancement

Renal Adenomas

Papillary adenomas are the most common renal epithelial neoplasm

According to autopsy series, approximately 40 percent of patients above the age of 70 harbor renal adenoma.

They are indistinguishable from RCCs. papillary adenomas measure 5 mm or less peak age in 5th-6th decades

a welldefined, unencapsulated, solitary solid mass. Metanephric adenomas display hypovascularity

and delayed, minimal enhancement

Metanephric adenoma

asymptomatic in many patients few with pain and hematuria.

IMAGING  difficult to differentiate from other renal tumours such as renal cell

carcinomas typically appears as a well-defined  expansile hypoechoic or

hyperechoic. , unencapsulated, solitary solid mass on sonography.  appears as a hyper attenuating mass on unenhanced CT; large tumors appear as heterogeneous, hypovascular masses with

frequent foci of hemorrhage and necrosis. Calcification is seen in 20% of cases

MRI: T1 hypointense , T2 hyper intense ;few hypointense

ANGIOMYOLIPOMA

These benign lesions are mesenchymal neoplasms A type of hamartomas Represents Excess growth of fat , smooth muscle and thick

walled blood vessels Amount of Each component is variable Histologically proliferation of perivascular Epitheliod cells

(PEComas) Tuberous sclerosis is the most commonly associated

syndrome. Multiple and bilateral angiomyolipomas should suggest the

diagnosis of TS Other assosciations include NF-1 , ADPKD, vHL

IMAGING

large, heterogeneous masses with varying amount of macroscopic fat

intralesional aneurysms and hypervascular soft tissues seen.

Angiomyolipomas are composed of thick walled inelastic blood vessels,

Risk of intratumoral and perinephric hemorrhage is higher in lesion > 4 cm diameter

USG:

hyperechoic lesions on ultrasound, located in the cortex and with posterior acoustic shadowing

in tuberous sclerosis, they may be so numerous that the entire kidney is affected, appearing echogenic with loss of normal cortico-medullary differentiation.

ontrast-enhanced ultrasound tend to enhance peripherally with decreased central enhancement, compared with normal cortex

CT

Most lesions involve the cortex and demonstrate macroscopic fat (less than -20 HU)

MRI

 excellent at evaluating fat containing lesions

Appear hyper in T1 wt images ,

In RCC also mascroscopic fat is seen. But lack of uniformity and capsular breach all be there

macroscopic fat in RCC almost always occurs in the presence of ossification/calcification,

absence of ossification/calcification on imaging is in favour of AML. 

DSA - angiography

Angiomyolipomas are hypervascular lesions demonstrating often characteristic features:

micro or macro aneurysms

sharply marginated

dense early arterial network

late whorled appearance

absent AV shunting

Renal lymphangiectasia

 is a rare disorder

dilatation of perirenal, peripelvic and intrarenal lymphatics.

aspiration of chylous fluid is usually confirmatory.

Haematuria, flank pain and abdominal pain

Ascites, renal mass, pyelonephritis and renal insufficiency have also been described

Subscapular fluid accumulation relative ischemia Secondary Hypertension.

Renal or perinephric inflammation, blocking the lymphatics

IMAGING

USG:

perirenal collection and peripelvic cysts

retroperitoneal fluid collection

ascites

poor corticomedullary differentiation and diffuse echogenic renal parenchyma

CT:

perinephric fluid attenuation collection of HU usually 0-10.

 Fluid collection in peritoneal or retroperitoneum compartments

Perinephric collection may give a page kidney like appearance.

MIXED EPITHELIAL AND STROMALTUMORS (MESTs)

This comprises of tumors previously referred to as hamartoma, adult mesoblastic nephroma.’

seen almost exclusively in perimenopausal women, most patients receiving estrogen therapy

imaging patterns including complex cysts, mixed solid cystic masses

show delayed and heterogeneous enhancement. On MR imaging the degree of delayed enhancement and T2

hypointense signal

It is typically seen as a multiloculated cystic renal mass with a variable proportion of solid and cystic components and containing internal septa. The latter may demonstrate heterogeneous and delayed contrast material enhancement

CYSTIC NEPHROMA

These are rare benign neoplasms that also show a female preponderance. Most patients are asymptomatic

predominantly unilateral, As well circumscribed cystic lesions with thin

septations. Hemorrhage or urinary obstruction may be caused by

the prolapse of the cystic mass into the renal pelvis.

Renal Cysts and Bosniack classification The Bosniak classification system of renal cystic

masses divides renal cystic masses into five groups.

based on imaging characteristics on contrast-enhanced CT

Useful in predicting risk of malignanacy and follow up

Classification

Bosniak 1 simple cyst, imperceptible wall, rounded

work-up: nil

percentage malignant: ~0%

Bosniak 2

minimally complex, a few thin (<1 mm) septa, thin calcifications; 

non-enhancing high-attenuation (due to to proteinaceous or haemorrhagic fluid)

renal lesions of less than 3 cm are also included in this category;

these lesions are generally well marginated

work-up: nil percentage malignant: ~0%

Bosniak 3

indeterminate, thick or multiple septations, mural nodule, hyperdense on CT (see 2F)

treatment/work-up: partial nephrectomy or radiofrequency ablation in elderly or poor surgical candidates

percentage malignant: ~54%

Bosniak 4

clearly malignant, solid mass with large cystic or necrotic component

treatment: partial or total nephrectomy

percentage malignant: ~100

Incidental Solid Renal mass If a large >3 cm solid mass is discovered, renal cell carcinoma

(provided there is no fat on CT/MR protocols) is the most probable diagnosis and surgery is recommended. If

the tumor is 1-3 cm in size, RCC is most likely though percutaneous biopsy may be required.

Very small lesions < 1 cm are more likely to be benign; thin sections (< 3 mm) used .

Obsevation and follow up CT/MR at 3-6months, then at 12 months and then yearly may be done.

Urinary bladder Tumors

Epithelial and no –epithelial

All epithelial tumors are malignant ;

E.g transitional cell type with squamous cell carcinoma and adenocarcinoma.

Non-epithelial tumors may be benign

E.g leiomyoma, fibroma

Malignant

E.g Leiomyosarcoma and Rhabdomyosarcoma

Various other primary tumors or masses may occur including pheochromocytoma, hemangioma, leukoplakia, lymphoma and endometriosis

Urinarybladder leiomyoma the most common mesenchymal tumor

accounts for only 0.43% of bladder tumors.

Leiomyomas occur equally in men and women with a wide age range of 22–78 years

Most are small and asymptomatic and are discovered incidentally.

However, large tumors manifest with symptoms such as hesitancy, frequency, dribbling, hematuria, pressure from mass effect, or urinary obstruction.

Leiomyomas arise in the submucosa,

but growth may be submucosal (7%), intravesical (63%), or extravesical (30%)

USG:

smooth-walled homogeneous hypoechoic solid mass in the bladder with thin echogenic surface 

Can determine the nature od spread

reveal smooth-walled solid lesion with homogeneous echogenicity

CT is accurate in detection and localization of these lesions, by presenting it as hypodense mass

contrast-enhanced CT scan the lesion is shown as a moderately enhan cing mass

MRI

Better demonstrating  sub mucosal origin of the tumour

the preservation of the muscle layer

The imaging characteristics are similar to uterine leiomyomas:

T1: intermediate signal intensity

T2: low signal intensity

degenerated leiomyomas have more heterogeneous signal characteristics; cystic areas have high signal intensity

T1 C+ (Gad): contrast enhancement is variable, degenerated areas lack enhancement

Neurofibroma

Neurofibromas of the bladder are rare,

The bladder is the most common genitourinary site of a neurofibroma.

They may be isolated or occur in association with neurofibromatosis type 1

Patients most commonly present with urinary tract infections. Other symptoms include hematuria, urinary frequency and urgency, mass, or obstruction

Characteristic CT and MR imaging features are diffuse, nodular bladder wall thickening with masses extending to the pelvic side wall .

MR imaging features are more specific Low signal intensity on T1-weighted images a target sign on T2-weighted images. which consists of low-signal-intensity fibrosis surrounded by

high-signal-intensity myxoid stroma

Bladder Hemangiomas

half manifest in childhood

the mean age is 58 years (range, 19–76 years) and they are more common in males in a ratio of 3.7:1

Painless gross hematuria is the most common presentation

a median size of 0.7 cm (range, 0.2–3 cm)

. Cavernous hemangioma is the most common type, accounting for 78% of cases,

capillary and arteriovenous types having equal rates of 10%

Most were single, broad-based, sessile bladder masses on the posterolateral walls

Hemangiomas are hypervascular masses at US, CT, and MR imaging

a focal, lobular, intramural mass OR diffuse bladder wall thickening 

MRI

low to intermediate signal intensity on T1-weighted images

markedly high signal intensity on T2-weighted images

Paraganglioma

preferred term for pheochromocytomas arising outside the adrenal gland.

 may rarely manifest as a bladder mass. 

They account for 0.1% of all bladder tumors and 1% of all pheochromocytomas.

The age range is wide at 10–78 years, and there is a female preponderance

A characteristic clinical syndrome of catecholamine release during micturition, “micturition attack,” occurs in 50% of patients.

Nonfunctioning pheochromocytomas are also reported.

CT  a solid, homogeneous, lobulated,

well-marginated mass, but cystic areas may result from necrosis or hemorrhage.

Submucosal in location and marked enhancement Post contrast .

Ring calcification around the circumference of the mass is highly suggestive of a bladder paraganglioma

Prostate cyst Midline prostatic cysts can be Müllerian duct cysts or utricle cysts.

Müllerian duct cysts do not contain sperms and can cause infertility due to compression of the ejaculatory ducts.

Utricle cysts contain sperms but unlike former do not extend beyond prostate.

The paramidline cysts are Wolffian cysts, seminal vesicle cysts or ejaculatory duct cysts which contain sperms.

Associated Wolffian duct \anomalies, i.e. renal anomalies may be seen in these patients

Peripheral cysts are acquired retention cysts and may be associated with BPH.

Cowper’s gland cysts are also acquired cysts associated with urogenital diaphragm.

Cystic lesions appear smooth walled, hypoechoic on USG

MRI: hyperintense on T2WI unless complicated by infection or hemorrhage

Adrenal Tumors

Pheochromocytoma catecholamine producing tumors which arise from ganglion cells.

Arise from anywhere in the autonomic nervous system.

Ninety percent of pheochromocytomas originate in the adrenal medulla,

10 percent are extra-adrenal,

the common sites being paravertebral sympathetic ganglia, organ of Zuckerkandl, urinary bladder, neck or mediastinum.

10 percent are extra-adrenal, Ten percent of pheochromocytomas are bilateral and 10 percent are malignant..

Clinical features of hypertension, paroxysmal attacks of palpitation, headache, sweating

biochemical tests of plasma catecholamine levels and 24 hours urine vanillylmandelic acid level can provide the diagnosis

IMAGING USG : seen as well-defined hypoechoic mass

which may show areas of necrosis or hemorrhage.

Accuracy for detection is less than that of CT MRI

CT is the technique of choice to confirm adrenal mass.

It is seen as soft tissue density mass with contrast enhancement on CECT

MRI MRI is the most sensitive modality for identification of pheochromocytomas,

and is particularly useful in cases of extra-adrenal location. The overall sensitivity is said to be 98% 

T1

slightly hypo-intense to the remainder of the adrenal

if necrotic and/or haemorrhagic then signal will be more heterogeneous

T2 markedly hyper-intense

areas of necrosis/haemorrhage/calcification will alter signal

T1 C+ (Gd) heterogenous enhancement

enhancement is prolonged, persisting for as long as 50 minutes 

Adrenal adenomas Represent nonneoplastic overgrowth of adrenocortical cells of zona fasciculata.

Consist of cholesterol laden clear cells and contribute little to steroid production

Functional and non functional types are seen

Imaging wise both appear the same.

They account for almost 90 percent of all incidentalomas

CT: Low attenuation well defgined mass (HU values rarely exceed 10HU).

Contrast study shows enhancement with washout in delayed phase

Mri

Adrenal Adenoma V/s Metastasis Adrenal adenomas have two properties that differentiate

them from non-adenomas.

. 70% of adenomas contain high intracellular fat (lipid-rich adenomas) and will be of low attenuation on unenhanced CT.

2. Adenomas rapidly wash out contrast.

Unenhanced CT : HU values less than 10HU Adenoma

If > 10HU then Contrast CT

Contrast CT :

Mild with rapid washout Adenoma

Hetrogenous moderate to intense enhancement Malignant or

Pheochromocytoma

The wash-out can be calculated by comparing the attenuation value at 60 sec with the attenuation value on a delayed scan at 15 minutes.

Adrenal Cyst Adrenal cysts are rare and usually seen in females.

derived from endothelium in 45 percent of patients

the rest are epithelial, parasitic or pseudocysts from prior hemorrhage.

CT shows characteristically well-defined round low attenuating lesion suggesting fluid with rim enhancement

Rim calcification may be noted

The attenuation values may be mixed in the presence of debris or hemorrhage

Adrenal Myelolipoma benign tumor of the cortex, comprised of mature fat and hematopoietic

elements

It accounts for about 7-15 percent of all incidentalomas.

Imaging appearance may vary depending on which histological component is dominant

USG : well-defined echogenic or heterogeneous adrenal mass,

may be associated with apparent posterior displacement of the diaphragm.

CT:

confirms presence of intratumoral fat.

Punctate calcification may be seen in 20 percent of cases

large myelolipomas may mimic retroperitoneal lipoma or liposarcoma.

GRE T1W in-phase (A) and opposed phase (B) image show a hyperintenseright adrenal mass which shows no drop in signal intensity but is suppressed on T2W fat suppressed image

Spotters

Double bubble sign

PINCER TYPE IMPINGEMENT

Lipoma of the filum terminale

is a relatively common finding on imaging of the lumbar spine, and in most cases is an incidental finding of no clinical concern.

In some patients however it may be associated with signs and symptoms of tethered cord syndrome. In such cases it is usually associated with a thickened filum and a low lying conus

Hamburger’s sign

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