Small Renal Masses

Posted on November 11, 2021 by - Medical Podcast, Podcasts, Urology

In this episode of PodMD, Melbourne trained Urologist Dr Kapil Sethi will be discussing the topic of small renal masses, including what small renal masses are, the natural history of the condition, the management options, when to refer and more.

  • Transcript
    Please note this is a machine generated transcription and may contain some errors.
    *As always, all in this PODMD podcast is intended for health professionals and the comments are of a general nature. Information given is not intended as specific medical advice pertaining to any given patient. If you have a clinical issue with one of your patients please seek appropriate advice from a colleague with expertise in the area.

    Today I’d like to welcome to the PodMd studio Dr Kapil Sethi

    Dr Kapil Sethi is a Melbourne trained Urologist with special interest in minimally invasive surgical techniques for benign and malignant conditions of the kidney, prostate and bladder. He completed international fellowships in advanced laparoscopy and robotics in Hamburg and Manchester and has public appointments at St Vincent’s and Austin Health, with a private practice in East Mebourne.

    Today, we’ll be discussing the topic of small renal masses.

    *We do hope you enjoy this podcast but please remember that the advice here is of a general nature and is not intended as specific advice about a given patient. The views and opinions expressed in this podcast are those of the doctor, not PodMD.
    If you do have a patient on whom you require specific advice, then please seek advice from a colleague with appropriate expertise in that area.

    Kapil, thanks for talking with us on Pod MD today.

    Kapil: Thank you for having me.

    Question 1
    The topic of today’s discussion is small renal masses, can you describe for our listeners what small renal masses are?

    Kapil: Sure, small renal masses are abnormal growths in the kidney that are usually less than 4 centimeters in diameter. These represent a heterogeneous group of both benign and malignant renal tumors, and the real concern for these lesions, is is the risk of underlying malignant potential, which by far and away is in the vast majority of them.

    Question 2
    How would we typically detect a patient to have a small renal masses (SRM)?

    Kapil: These days it’s nearly impossible to go through life without having some sort of abdominal scan. So, these masses are almost always incidentally detected during ultrasound or CT imaging for nonspecific reasons. As these are usually caught quite early, while they’re small, they tend to be asymptomatic. And I’d say we probably definitely apply the attitude of modern medicine, where you know, continue looking into the human body. You’ll end up finding something, and that’s certainly the case here and in the case of small renal masses, it’s definitely a good thing. So we have close to about two and a half thousand cases of renal cell carcinoma diagnosed in Australia each year.

    Historically, about 1/3 of these were always metastatic at diagnosis, and unfortunately it would prove fatal is there’s no systemic cure for this disease, so we’re seeing that a lot less because we’re detecting them early when they’re much smaller. The risk of metastatic potential of a small renal mass less than 4 centimeters is less than 4%.

    Question 3
    What is the natural history of this condition?

    Kapil: OK, so this is somewhat dependent on the type of renal mass that we’re dealing with. About 80% of small renal masses are malignant and their conditions, such as renal cell carcinoma, clear cell carcinoma pillory carcinoma. About 20% tend to be conditions where they’re benign, and these things like angiomyolipoma or oncocytoma, sometimes they’re reported on radiology reports. Both benign and malignant renal masses may grow in size, but the average growth tends to be really slow. It’s usually between about one in three millimeters a year.

    Question 4
    What are the management options?

    Kapil: So there’s an excellent number of really wide management options for small renal masses. These include both surgical and non-surgical approaches that we can apply. It’s really dependent on a number of characteristics and tends to be quite individualized, so this depends on patient characteristics such as Age and comorbidities, as well as more objective features such as renal function, tumor characteristics such as size, location on the kidney or histological confirmation of cancer. So taking these into consideration we can apply really personalized a risk adapted approach. The end game here really is to keep them alive by curing any cancer and keeping our patients off dialysis. So to go through this in a bit more detail. If we, for example, have a younger patient with an incidentally found small renal mass, we may wish to consider renal biopsy for histological confirmation cancer.

    In someone who doesn’t have any major comorbidities by far, and away the communist approach for treatment would be for the patient to undergo a partial nephrectomy where just the tumor and a small area of surrounding tissue is removed with the vast majority of kidney preserved. This is now routinely done by minimally invasive techniques such as laparoscopy or robotics, and allows maximal long term preservation of healthy nephrons. A radical nephrectomy is where we remove the entire kidney, and this has become a historical operation for small renal masses. So in a radical nephrectomy it is usually reserved for more technically challenging cases where we’re not confident that the small renal tumor can be successfully removed to achieve a good oncological outcome and without complications such as bleeding. Since partial nephrectomy me carries a slightly higher risk of bleeding than radical nephrectomy, we may offer a radical nephrectomy in these patients, where the complications may be higher and a long term nephron preservation, because it becomes less of an issue due to lower life expectancy.

    If you do have an older patient and someone who may have a number of comorbidities, we’ve got the conundrum of having someone who’s unfit for surgery and the risks and complications of surgery may be high and outweigh any benefit in overall survival. So are suitable option in these maybe active surveillance. Through this approach, we would confirm the diagnosis by biopsy and monitor the renal mass, which as mentioned tends to be very slow growing every 6 to 12 months or so. Uh, if the tumor increases in size or starts creeping towards those 4 centimeters, a very good option in these cases maybe focal ablation by minimally invasive techniques such as radiofrequency ablation or cryoablation. This is where the radiologist basically sticks a needle in the tumor and knocks the tumor off by heat. In the case of RFA or by cold in the case of collaboration, so there’s no long term data to suggest that this technique is durable, so it’s therefore reserved really just for patients with a limited life expectancy and not routinely used in younger patients.

    Question 5
    Have there been any recent developments in the way this condition in managed in the last few years?

    Kapil: Sure, so the issue for a long time has been over treatment of small renal masses with these masses. Like I said, 20% of them are benign. It hasn’t really been a great way to differentiate benign and malignant small renal masses on standard ultrasound or CT, so there are some really clear cut cases where we can clearly say some of these masses may be benign and such as an angiomyolipoma which has fat in it or an uncle side which sometimes has a scar, but as a tiebreaker we used to biopsy these lesions but we couldn’t really diagnose the masses benign with any confidence due to historically high false negative rates.

    These patients that then go off and have a partial or radical nephrectomy. Meaning we would be over treating benign masses in this situation, so we’ve really evolved in the last few years and we have, along with our radiology and pathology colleagues being able to apply quite sophisticated imaging techniques such as contrast. Enhanced ultrasound and dedicated MRI to help differentiate these lesions with a lot more accuracy.

    So contemporary data also suggests that we now have over about a 90% accuracy of diagnosis with percutaneous renal biopsy much better than it’s ever been. And another really interesting area of development is the growing use of stereotactic radiotherapy, which is called Saber. This is getting excellent results to ablate renal masses that are typically outside of the size range for you know Cryoablation or other BLT if techniques and it really works well for much larger achievements now.

    Question 6
    Are there any warning signs a GP or their patient can look out for?

    Kapil: OK, sure, so the classic teaching always used to be patient with kidney cancer would have hematuria flank pain and a palpable mass, but that really doesn’t apply in small renal masses. We rarely see any clinical features and if we do, these usually indicate quite advanced disease. So the real warning signs for a GP would be that if there was any solid component to a small renal mass, or if there was a cystic lesion that demonstrated any complex features, this could be things like calcification on assist or area of enhancement around this cyst. Then this really needs specialist review.

    Question 7
    We often see renal cysts detected during scans? Do these cysts pose any threat or are they linked to the other conditions you have mentioned?

    Kapil: So renal cysts are really common, just as assisting other organs of the body in the urinary system. We see them in the epididymis and we also see cysts on the liver and the pancreas routinely. For example, so simple cysts can be quite easily radiologically defined, and these tend to be smooth outline of a fluid filled SAC with no complicating features such as calcification, septation, or enhancement that I mentioned earlier. So from time to time reduces some complexity within these cysts in there may be such things, such as an area of an enhancement around the cyst, or some septations that go through them, or some calcium deposits. These would be classified as a complex renal cyst and it has its own grading system called a Bosniak classification. Uh, really, really small number of these complex cysts would have an underlying malignant potential and may require monitoring after a dedicated imaging and specialist review.

    Question 8
    When should a GP refer?

    Kapil: So if there’s any radiological finding a simple cyst and it’s clearly called a simple renal cysts with no abnormal features that I just mentioned. Then nothing further is usually indicated. If there are any clinical features such as dull flank pain associated with assist, then a specialist review may be warranted and for basically any other small renal mass. Referral should be made to a specialist and this will really help delineate the malignant potential and any further investigations that are usually required for these masses.

    Question 9
    What role does the GP play in the treatment of the condition?

    Kapil: A very important one. So the important task would be primarily in the detection in the first instance, so screening is not usually warranted, because like I said, we’re looking at two and a half thousand cases in Australia per year, so that wouldn’t warrant a wider screening program, but if they do go on to have an incidentally found small renal mass. This allows us to catch any disease early and offer appropriate treatment in cases where patients are also undergoing surveillance by either active surveillance or post operative surveillance and there may be a shared care model that’s been arranged with the GP. After discussion with your specialists about how and when to offer imaging just to monitor the kidney afterwards.

    Concluding Question
    Thank you for your time here today in the PodMD studio. To sum up for us, could you please identify the three key take home messages from today’s podcast on small renal masses.

    Kapil: Three take home messages are. The first would be that small renal masses are increasingly detected. Most are malignant, but grow slowly and have a very low metastatic potential.
    So all of these need to be reviewed by a specialist to help differentiate the nature of the mass.
    And #3 all cancerous tumours offer excellent cure rates with treatment tends to be very individualized to each patient.

    Thanks for your time and the insights you’ve provided.

    Kapil: Thank you for having me

*As always, all in this PODMD podcast is intended for health professionals and the comments are of a general nature. Information given is not intended as specific medical advice pertaining to any given patient. If you have a clinical issue with one of your patients please seek appropriate advice from a colleague with expertise in the area.