Role of Ultrasound in The Management of Renal Masses - SD

Introduction

My name is Dr. Mike Hill
and I'm a diagnostic radiologist from the George Washington
University Hospital in Washington DC.
The title of my talk today is the role
of ultrasound in the management of renal masses.

Role of Ultrasound in Renal Masses

Ultrasound has a important role to play in the management
of renal masses and during my talk this afternoon,
I will address the simple renal cyst,
either single or multiple.
I will also address diffuse cystic disease of the kidney,
including adult type polycystic kidney disease
and acquired cystic kidney disease.
I will address in particular three benign tumors called
oncocytoma angio, my lipoma and multilocular nephroma.
And finally, I will address malignant tumors including renal
cell cancer, lymphoma,
and metastatic disease to the kidneys.

Ultrasound characterizes renal masses into cystic and solid.
A cystic mass can be simple or complex
and a solid mass can be hypo coic, hypo coic, or iso coic.
Either cystic or solid masses can be single or multiple
and based upon these findings,
one can reach a reasonable diagnosis.

Simple Renal Cysts

In most cases, there is a way
of classifying renal cyst based upon the
CT appearance of cyst.
And I will mention this classification
because of its use in the general population
of physicians in this country.
It's called the Bosniac classification.
A simple cyst is the type one
and this on CT scanning has a water density,
usually less than 20 hounds field units.
A type two cyst is allowed to have a thin septation
and even thin calcification, which should not enhance
both the one and two cysts are benign.
The two F lesion is possibly benign
and includes a hypertense cyst as seen on CT
and also a thick calcified cyst seen on ct.
When one gets into the type three
where you have thick septations coarse calcifications
with variable enhancement, it is problematic
that the lesion is probably going to be a renal cell cancer.
And finally, type four deals
with the large necrotic cystic mass
with a thick irregular enhancing wall,
and this is definitively going to be a renal cell cancer.

Now the simple renal cyst is very common.
In fact, 25% of people over the age of 50 years
of age have these simple cysts.
These cysts can be within the parenchyma of the kidney
or they can be in a PARP location.
They tend to be round to oval in shape,
have a thin smooth wall, no internal echoes,
good truth transmission,
and may contain a single thin septum.
And this is just an example
of a simple cyst involving the kidney.
We can see it here as a very smooth, round shaped
low density lesion with no internal echos,
a very nice thin wall
and some good through transmission consistent
with a simple renal cyst.

Now where ultrasound is extremely helpful is in the case
where on a CT scan you have a small mass in the kidney
and it measures let's say over 20 hansfield units
and you cannot prove it as a cyst.
By taking your ultrasound transducer
and scanning directly over this lesion,
you can in fact prove that this is,
this is in fact a benign cyst
that does not need any further workup.
And here's an even smaller lesion seen on a CT scan.
A very tiny indeterminate lesion in the kidney is this
cystic or a solid mass.
While the ultrasound here shows you that this is a very nice
thin walled cyst with a slight degree of
of true transmission and so
therefore again, a benign cyst which does not need any
further workup.

Hyperdense Cysts

Now on CT scan, another problematic lesion
for us is what's called the hyperdense cyst.
This is a non-contrast CT scan demonstrating a mass in the
kidney that is more dense than the surrounding parenchyma.
And this density can vary from 60 to 90 household units.
This could represent a renal neoplasm
or it could represent a hyperdense cyst.
And ultrasound again has a critical role to play by showing
that in fact, this uh, lesion is in fact a cystic lesion.
Again, a thin wall, an coic and good through transmission.
No internal vascularity with color doppler imaging.
Therefore, again, this is a benign system,
does not need any further workup.

Ultrasound is also a very sensitive tool
in looking at the internal architecture of cysts.
Looking at a well performed CT scan here
with contrast shows a cyst in the kidney,
but you can't see the septation,
which is very nicely demonstrated by ultrasound.
So when I have cystic lesions on CT where I'm trying
to determine their internal architecture,
I'll use ultrasound as a way of doing this.
In this instance here on a CT scan, we have a lesion
that has got wall calcification.
I could not give this patient contrast
because he had renal failure and
therefore I went to ultrasound which demonstrated
that this in fact was a very nice thin walled cyst
with no internal echoes and
therefore this will be a cyst that
that will be safe to follow.

Contrast the previous lesion with this lesion where you have
a cyst with a lot of complex internal septations
and in fact with mural nodularity at this stage of the game,
we are not going to call this a simple cyst.
This is a complex cyst which could
represent the renal cell cancer.
And on on the right here we have the CT scan demonstrating
calcification within the cyst with mural nodularity
and this lesion turned out to be a renal cell cancer.

Parapelvic Cysts

Now, PARP pelvic cysts are cysts
that occur within the renal sinus.
They may be unilateral or bilateral
and are of lymphatic origin.
The problem with these cysts is when they are multiple,
they can mimic hydronephrosis
and even at ultrasound they can create difficulty
and in which case a contrast enhanced delayed CT scan may be
necessary to prove that in fact they are paralytic cyst
and not hydronephrosis.
Here we have a have an example of the right
and left kidney demonstrating what one could surmise,
could be hydronephrosis.
But when one does the contrast enhanced delayed CT scan,
we can see that the contrast within the UM collecting system
is actually being compressed by these PARP cysts.
So this is not a, uh, an example of hydronephrosis,
but in fact represents para pelvic cysts
compressing the renal collecting system on both sides.

Diffuse Cystic Diseases of the Kidney

Diffuse cystic disease of the kidney,
the most common type would be the autosomal dominant
polycystic kidney disease.
We are now seeing more
of acquired cystic kidney disease in dialysis patients
and I will address that in just a moment.
Anytime we see cysts in the kidney, there are diffuse.
We have to consider von Hippo lindo disease
and also tubal sclerosis.

Autosomal Dominant Polycystic Kidney Disease (ADPKD)

Now with autosomal dominant polycystic kidney disease,
a family history of the disease is present in about
50% of patients.
Renal failure usually has its onset in 50% by the age
of 50 to 60 years.
However, some people can get very old
and not develop renal failure from this disease.
Cysts are also found in the liver in approximately 60%
of patients and occasionally in the pancreas and spleen.
This disease is also associated
with cerebral bar aneurysms in about 18 to 40% of patients
in autosomal dominant polycystic kidney disease.
The kidneys are large, the cysts are multiple
and they vary greatly in size from
millimeters to centimeters.
Occasionally some of the cysts may have echogenic debris
which is usually due to hemorrhage.
However, infection can also produce a similar picture
because of the hemorrhage,
they can develop dystrophy calcification in the wall
of the cysts and stones do develop in the collecting system
because of the compression
of the collecting system by these cysts.
And this is an example of the right
and the left kidney enlarged not massively
so containing numerous cysts of various sizes.
And this is typical
for autosomal dominant polycystic kidney disease.
Here we have an example in the same patient
of a CT scan demonstrating the cyst.
You can notice the small little punctate
calcifications in the cysts.
You'll also notice that there are
liver cyst presence as well.
This is a T two weighted MR sequence in the coronal plane
demonstrating cyst in the liver here
and also in both kidneys.

Acquired Cystic Kidney Disease

Now acquired cystic kidney disease occurs in patients on
long-term dialysis.
Usually after five years these cys tend to be
of a smaller size from 0.5
to three centimeters in both kidneys.
They also tend to be of a uniform size,
unlike adult type polycystic kidney disease, which tends
to have cysts varying size from millimeters
to many centimeters.
This disease is due to the presence
of epithelial hyperplasia leading to tubular obstruction
and also as in adult type polycystic kidney disease
cyst hemorrhage can occur.
Renal cell cancer is also common in these people occurring
in about four to 10% of patients
and this is an example of acquired cystic kidney disease,
the right kidney, the left kidney,
the kidneys are not enlarged.
They do contain cysts of a fairly uniform size.
And we can also see a similar image here on the
non-contrast enhanced CT scan.

Now all cases of acquired cystic kidney disease
do not appear similar.
In this instance here we actually have a case
where it actually looks like adult type polycystic kidney
disease where the kidneys do appear somewhat
enlarged on both sides.
We have multiple cysts of various sizes.
I know this is acquired cystic kidney disease
because we had a scan done seven years prior
to the patient going on long-term dialysis
and the kidneys looked relatively normal
with a few small scattered cysts not consistent
with um adult type polycystic kidney disease.
So in fact this is is a case
of acquired cystic kidney disease
that in fact mimics adult type polycystic kidney disease.
But obviously the history will help solve this problem.

Benign Renal Tumors

There are three benign renal tumors.
I would like to discuss the multilocular, nephroma,
the oncocytoma and the angiomyolipoma.

Multilocular Nephroma

Now the multilocular nephroma as its name would imply,
is actually made up of a collection of uh,
cyst clumped together almost like in a grape like fashion.
And these cysts love to invade into the sinus of the kidney.
As we see here. They tend to be solitary,
they tend to be unilateral.
They're well-defined encapsulated multilocular cystic mass
that as I said already like the herniate into the renal
hilum with contrast have variable enhancement
and they can also calcify.
However, they cannot always be distinguished from a
multiloculated cystic renal cell cancer.
Here's an example of my practice where I believe
that this was a a renal cell cancer.
It had a multid appearance
with somewhat irregular looking septa.
As we look at the contrast scan here, the SEPTA did appear
to enhance there was some calcification
and this is the pathological specimen.
But at the time of surgery this was taken out.
Pathology proved it to be a multilocular nephroma.
So again, not all
of these cases can be distinguished from a renal cell cancer
and may need to be removed.
To prove this point, in this instance here we have an
echogenic mass arising from the lower pole of the kidney
and when I initially looked at this, I was assuming
that this could be either a solid renal tumor
or an angio myel lipoma containing fat.
I did a T one and T two weighted MR sequence T one, uh,
weighted MR sequence.
One can identify that the mass in the kidney is in fact
of less intensity than the normal renal parenchyma.
On the T two weighted sequence we can see
that it is bright in relationship
to the normal renal parenchyma proving
that this lesion contains water.
If one looks carefully, one can actually see
that this has little small septa within it
and this in fact turned out to be a multilocular nephroma.
Here's a gadolinium image in the coronal
and axial planes demonstrating
that this lesion does not enhance with gadolinium.
So going back to look at this lesion again
for the second time, if one looks carefully,
although this lesion is echogenic, it does have good
through transmission and if one can looks carefully,
one can see small cystic spaces in this echogenic mass
and this when seen should suggest the presence
of a multilocular Nephroma

Oncocytoma

oncocytoma are tubular adenomas are solid,
well demarcated cortical masses.
They tend to have homogeneous enhancement
and may have a central stellate scar in 30 to 50%
of cases which can help prove the diagnosis.
They can undergo hemorrhage
and sometimes they can even calcify.
They can be multifocal bilateral
and they can be found in conjunction
with renal cell cancers by themselves.
However, they do not produce any lymphadenopathy.
They not do not produce metastasis
nor do they invade the venous system.
Here we have an ultrasound example of a lesion
that actually looks like a donut
with a black hole in the center.
The actual parenchyma of the lesion looks echogenic
and the central stellate scar area looks hypoechoic.
Here we have a non-contrast CT scan of the same lesion
followed by a contrast enhanced CT scan
and again showing you the central stellate scar here
with the peripheral dense enhancement
of this lesion consistent with an oncocytoma.
A somewhat similar appearing lesion,
again showing you an echogenic mass in the kidney
with a central hypo coic scar which actually does contain
some small calcifications here
with shadowing on the non-contrast CT scan you can see this
less dense area in the center followed by contrast.
One can see the central stellate scar here
and the tumor in this area out here consistent
with a renal oncocytoma.
This one's somewhat less characteristic.
Pedunculated coming off the end
of the kidney is slightly more echogenic
than the normal kidney.
Has a central hypo coic area consistent with a central scar
and again the CT scan not particularly helpful here
as in fact uh,
the CT scan would suggest more a renal cell cancer than a
renal oncocytoma.
However, at pathology, the ultrasound was proven true
that this was in fact a benign renal oncocytoma
and not a renal cell cancer.
So the central scar is the hallmark of this tumor.

Angiomyolipoma

Now angio, my lipoma is the most common benign tumor
that one finds in the kidney.
95% of these contain fat allowing us
to identify them as angio.
My lipomas. They are found multiply, uh,
in in tuber sclerosis.
So when one sees multiple angio, my lipomas one should think
of tubo sclerosis on ultrasound
because of the presence of the fat within the lesion,
they are echogenic and this can be proven
by CT or M or scanning.
These tumors do like to hemorrhage
and so when they reach a size greater than four centimeters,
they're usually uh removed.
They may also on rare occasions invade the inferior vena
cava and simulate a renal cell cancer.
In this example here we have an echogenic mass in the kidney
in which one would state that this is probably some kind
of tumor and angiomyolipoma is a possibility
including renal cell cancer.
On the CT scan
however, we have a non-contrast scan on the left here,
a contrast scan on the right one can identify that this mass
has a hands unit measure of minus 34 consistent with fat.
And in fact if you just look at this with your eyeballs here
and compare it to the subcutaneous fat, you can see it's
of the same density convincing you
that this is in fact a fat containing angiomyolipoma.
Another example of a somewhat larger tumor,
again a echogenic tumor in the kidney.
When you look at the CT scan without contrast,
you can identify this low density fat in the
center of the lesion.
Now a somewhat different appearance of an angiomyolipoma
and this is kind of confusing
because here it really looks like a normal looking kidney
surrounded by very echogenic fat
and in fact if one wasn't um, skilled enough in identifying
what this was, you could miss the diagnosis
because on the CT scan here we can actually identify
that this angiomyolipoma is arising from the anterior aspect
of the kidney and because the fat surrounding the
or within the mass is so pliable that it, it allows itself
to be compressed between the kidney
and the liver, thus giving it the appearance
of perinephric fat on on this slide here.
So angio lipomas can in fact
because of their soft pliable nature,
oftentimes when they're large like this,
look like perinephric fat.

Malignant Renal Tumors

Now onto malignant renal tumors, these may be single
or multiple renal cell cancer lymphoma
and renal metastasis are all included in the differential
of a solitary renal mass
with obviously renal cell carcinoma being the most common
and renal metastasis being very rare.

Renal Cell Carcinoma

Now ultrasound of renal cell carcinoma, the solid ones tend
to be hyper coic in about 50% of cases.
They tend to be ISO coic in 40%
and that's the reason why small
solid renal cell cancers are hard to see with ultrasound
and about 10% of cases they can be hypoechoic.
The cystic type of renal cell carcinoma tends
to have a thick irregular wall and thick septa.
It tends to have neur nodules
and calcifications in about 10%
and as I mentioned already,
these cystic lesions can be multifocal and bilateral.

Now renal cell cancer likes to metastasize to the liver
to adjacent retroperitoneal lymph nodes
and also to the adrenal glands.
So when we do see a mass in the kidney we should look at the
liver and the adjacent retroperitoneum
and also look for a an adrenal mass.
We should also look for venous invasion
and this is most common arising from the right kidney
because the right renal vein is shorter
than the left renal vein.
Another pointer is since these tumors can be multiple
and can be synchronous,
one should always look very carefully at the opposite kidney
to make, make sure there is not a small renal cell cancer on
the opposite side, which would obviously change treatment.

Here's an example of a non-contrast CT scan
where there's a very subtle evidence
of a low density mass in the kidney.
However, the hounsfield units did not
suggest this was a cyst.
We could not give the patient intravenous contrast.
So again, ultrasound came to the rescue
and showed that this mass was in fact not a cyst
but in fact was a a solid renal neoplasm.
And this was proven by a
contrast enhanced gadolinium performed amor scan
of the kidneys in the axial coronal plane showing this mass
to be a solid enhancing mass in the kidney consistent
with a renal cell carcinoma which was surgically removed.

Another example of a solid renal cell carcinoma in the
kidney, A rather large tumor here.
This tumor was staged by ct.
There was no evidence of any renal VA renal vein invasion,
no evidence of retro peritoneal lymphadenopathy, no evidence
of liver metastasis.
There was some concern
that the mass might be invading into the SOS muscle
but at the time of surgery this turned
out not to be the case.

Here we have another example
of a solid renal cell carcinoma here arising in the upper
pole of the right kidney.
Again, we can see no evidence
of renal vein invasion on ultrasound
and no evidence of liver metastasis.
This is the adrenal tumor here without contrast here.
And then with contrast over in this area here,
this is just an example of retroperitoneal lymphadenopathy.
Here's the spine here
and here's the lymph nodes wrapping
around the aorta in the midline consistent
with retroperitoneal lymphadenopathy, an example
of metastatic disease to the to the liver in this instance
and the companion image to this case is as follows.
Here we have invasion
of the tumor into the inferior venia cava.
It was not obstructing flow,
there was still flow towards the heart
and this tumor was not invading into the heart itself.
Here we have an ex the ultrasound image
demonstrating diffuse involvement of the left kidney
with the tumor we can identify the tumor invading along the
left renal vein going into the inferior venia cava
and here we have an R scan demonstrating the the mass
within the left kidney.
We can identify the tumor extending along the left renal
vein, not only up the IVC
but also in a retrograde fashion down the IVC.

Now how good is uh ultrasound in the detection
of renal cell carcinoma?
Well this depends upon not only its echogenicity
as I already mentioned but also on its size.
For example, a three centimeter lesion
and above has a 85% chance of being detected by ultrasound.
However, when you get to a lesion two centimeters
or less, the detection rate will will go below 60%.
So I guess the point to be made from this is
that ultrasound really cannot be used to screen
for small renal cell carcinomas.

Is it safe to follow a small renal tumor?
Well that depends upon the patient's, uh, age.
It depends upon comorbid factors
and also the rate of growth of tumor,
which I will just discuss in a moment.
Obviously a young person in his forties
or fifties with good health,
obviously the tumor should be taken out.
If on the other hand the patient is 85 years
of age in a nursing home with cardiopulmonary disease,
not a very good risk factor for surgery,
then such a patient could probably be followed.

Now the growth rate, well there was a study done by Bosniac,
uh, which is on this slide here
where he followed 49 patients
for periods ranging from 1.8 years all the way out
to 8.5 years and in 30 tumors he found
that the tumor grew out a a fairly slow rate
of half a centimeter per year
and the other 19 tumors grew at a rate of one third
of a centimeter per year.
So it is reasonable in some patients
to actually follow the growth of tumors, uh,
taking into account age and comorbid features.
Um, as factors,

Multiple Solid Renal Masses

multiple solid renal masses can be due to many causes.
They can be due to renal cell carcinoma associated
with genetic diseases such as um, Von Hippo, Linda disease.
We can also see multiple lesions in the kidney with lymphoma
and also with metastatic renal disease.
Metastatic renal disease can be either solid or complex
and common sites of origin are include the lung, the breast,
the colon, the pancreas, and of course melanoma.
Here we have an example
of multiple mass lesions in the kidney.
These lesions are echogenic and
therefore these are unlikely to be lymphoma,
however they could be metastatic disease
but in my practice I rarely see metastatic
disease to the kidneys.
So renal cell carcinoma will be on the list
and the fact this patient is a patient
who has von hip Linda disease,
this is an autosomal dominant disease in which renal cyst
occur in 60% and renal cell carcinomas occur in about 35%.
They also have CNS heman glioblastomas
and also they have heman oblasts in the retina
and in the cerebellum they are also associated
with pancreatic and liver cyst and neuroendocrine tumors
and 12% of them will develop pheochromocytomas.
And this is just an example of a CT scan
of the previous patient I just showed you showing you cystic
and multiple solid masses throughout both kidneys in this
patient with von Hippel, Linda disease
and multiple renal cell cancers.

Renal Lymphoma

Now renal lymphoma does tend
to look different than renal cell car in
that it is a hypo coic mass
and often the these lesions are multiple throughout
the renal parenchyma.
They can also infiltrate into the renal sinus
and they can also infiltrate
around the kidney giving it a characteristic appearance.
In this instance here we have an HIV positive person
with multiple high coic areas throughout the kidney
and the CT scan demonstrates the same entity in which you
have multiple hypodense lesions throughout the kidney
and on biopsy these prove to be renal lymphoma.
Other things that renal lymphoma can do is,
as I said already it can invade into the renal
sinus as seen here.
It can also wrap itself around the kidney
and the fact it can mimic perinephric fluid.
The corresponding CT scan here shows the tumor going into
the kidney sinus and also surrounding the kidney as here.
And this is fairly typical appearance for a renal lymphoma.

Pseudotumors on Ultrasound

Now there are pseudo tumors on ultrasound scanning which
one has to be aware of.
So as we don't over-diagnose a tumor
and these include the renal pyramid, the column of bertan
junction zone renal loation focal oph is all the way
to a renal abscess.
In this instance here at first blush that could be mistaken
as a cyst but one will notice
that there is really no evidence of any any cyst wall here.
And this fact represents just a hypo coic renal pyramid.
Here we see an echogenic mass along the upper anterior
aspect of the kidney which has the appearance
of an angiomyolipoma.
However, on longitudinal scanning one can see
that this echogenic mass assumes a triangular shape
consistent with fat within the junction zone of the kidney.
As you may know, the the kidney is formed of a dorsal
and ventral part which fused like a sandwich
and sometimes there is a defect at the upper end
of this junction line which traps extra um, renal fat
and makes this look like an angio
myel lipoma, which it is not.
Here we have an enfolding of the cortex here
between the two collecting systems
of this kidney simulating a renal mass,
but again, this is not a mass, it's normal renal parenchyma.
We can also have bumps along the kidney,
which can sometimes look like a tumor as we see here.
Difficult to see on the axial view
and that's often the tip off
that this is in fact not a true tumor.
And when you do a CT scan you can see
that this little bump here in fact is just a normal loation
of the renal surface and does not represent a renal tumor.
In this instance here we have a longitudinal scan
of the kidney demonstrating a mass within the upper pole
here and here and then when one goes
to the CT scan you can see the mass here.
However, we also have a straight nephro in this kidney
consistent with focal pyelonephritis.
So this hypo coic mass here in the kidney in fact represents
a focal area of pyelonephritis.
And again, the history here would be very helpful
because one would expect this patient to have a fever
leukocytosis flank pain and
and pussing the urine In this patient.

Here we have an irregular mass within the mid
to lower portion of the kidney in contradistinction
to the cyst, which is at the upper pole.
Here this cyst contains internal echos
but does not have any internal vascularity
and this is in fact a renal abscess in a diabetic patient.
You're showing you the abscess here again, a nice example
of the, of the poor margination of the sepsis
with internal echos within the kidney.
The non-contrast scan here
and this was treated by percutaneous drainage.

Indications for Biopsying a Renal Mass

Now what are the indications for biopsying a renal mass?
Well, first of all, if you have a primary renal mass
and metastatic disease to other areas
where the tumor is not resectable, then it's reasonable
to perform a biopsy to prove that the well
to confirm whether the mass in the kidney is a primary renal
cell cancer or a metastatic lesion.
It can also also be done in patients
with suspected renal cell carcinoma with metastasis.
We also perform it prior to tumor ablation
or prior to focal resection to prove
that the lesion we are resecting is in fact
benign or malignant.
One can use either ultrasound
or CT guidance to biopsy the mass.
You can use a small needle 20 gauge
or above for cytopathology
or you can use a large cutting needle 18 gauge
or 16 gauge for histology.
And this allows one also to look at the immuno cytology
and cytogenetics of the biopsy specimen.
The diagnostic accuracy of a biopsy is in the 85
to 95% range for diagnosing malignancy.

Now ultrasound biopsies are sometimes performed
because one cannot always tell whether the lesion is a
benign solid mass or a malignant solid mass.
In this instance, in a report by Frank from the Journal
of Urology in close to 3000 nephrectomies, 12.8%
of their lesions were benign.
And as one might expect,
the most common one was the oncocytoma followed
by the angiomyolipoma
and followed by the adenoma of the kidney.
Size also does determine the rate of malignancy
and as one might imagine the smaller the lesion,
they're more likely it is to be benign.
In this study by Frank, again,
we see lesions less than one centimeter,
where in fact almost half of them were benign.
When the lesion got
to two centimeters when approximately one third
of them were benign, but then above three, the uh,
the benign sea rate fell to 25%.
So small lesions are probably benign,
larger ones are probably malignant.

Well, this biopsying a real massive impact on clinical
management when in, in this paper by wood at all,
it did in 73 patients, um, 41%
of 'em had their clinical management changed by the biopsy
because in this instance they only found malignancy in 62%
of the lesions and the benign lesions were 31%.
So that's one third, uh,
the biopsy specimens were non-diagnostic in about 6%
when one has an extra renal primary with,
with a renal mass in this paper by Rebecca of 54 patients,
20% of these biopsies were shown actually
to represent metastatic disease,
but actually 31 were shown to represent renal cell cancer.
So therefore, when one sees a mass in the kidney,
even though you have a known primary elsewhere,
a biopsy is necessary to prove that
that lesion is a metastatic lesion and not renal cell cancer

Biopsy of Cystic Renal Masses

Is biopsy of cystic renal masses indicated.
Well, this is a debatable point.
Um, in a paper by Harsin Gian, he actually showed
that in his 28 patients with bosniac three criteria lesions
that actually 40% of them turned out to be benign
and 61% turned out to be malignant.
He did this by using a combination
of fine needle aspirations and also core biopsy needle.
Obviously since one one can of biopsy,
the entire mass benign results are not really definitive
and these lesions would need
to be followed even though they could be benign.
This is just an example of a lesion in the kidney
with a small amount of calcification.
Here we have an ultrasound guided biopsy
needle in the lesion.
Question is, is it safe?
Well, in a large series of biopsies, um,
of over 1000 patients in patients
and all of these patients were normotensive,
they had normal coagulation factors
and they were not on aspirin.
There were four major hemorrhages, three three
of which required transfusions
and one required an interventional procedure
to stop the hemorrhage.
So really ultrasound guided renal biopsies is a safe
procedure and has a low acceptable risk rate.

Thermal Ablation of Renal Tumors

Now how about the thermal ablation of renal tumors?
What are the indications?
Well, it can be an alternative to a partial nephrectomy.
This can be maybe due to the patient's age
or comorbid features.
Also, how about if the patient only has a single kidney left
and you don't want to remove it and make the patient a neph.
Also in a patient who may have marginal
or renal insufficiency where you don't want
to take out the kidney and put them on dialysis.
Again, one has to factor in all
of these things including the surgical risk, the age
of the patient and cardiopulmonary disease.
In our institution we do most of these
CT guided thermal ablations using uh, CT guidance.
But other people, other places
use actually ultrasound guidance.
Once we do a biopsy of the lesion, we actually, um, uh,
thermally ablate it.
We then follow that with a contrast enhanced CT scan
to make sure we have not left
behind any residual enhancing tumor.
And then of course, we follow these patients up
with frequent intervals starting at three months
by giving them contrast enhanced um, CT scans
to make sure there is no evidence
of any residual tumor left.

Summary

So in summary, ultrasound is a very useful tool in helping
to characterize the nature of a mass seen on a CT scan.
It can divide lesions into cystic and solid renal lesions
and also can be used in the management
and follow up of such lesions
as hopefully I've demonstrated to you.
I would again like to emphasize it is not a screening tool
for small solid renal masses
and um, ultrasound is also a useful tool for guiding biopsy
and also for guiding thermal ablation.
Thank you.