Page 4 - Role of renal mass biopsy in the management of kidney cancer: KCRNC

Lavallée et al

8. Patients who have a renal mass biopsy with benign ing will be recommended irrespective of the biopsy
histology should be informed about the risk of a false result because of competing risks.
negative biopsy and should be monitored. 10. Renal mass biopsy should not be recommended to
Renal mass biopsy can be an important diagnostic tool to patients who will want to proceed with definitive man-
guide the management of a patient with a renal mass. Prior agement irrespective of the biopsy result.
to ordering a renal mass biopsy, a physician must evaluate 11. Renal mass biopsy should not be performed in patients
the patient’s values and preferences with respect to manage- with a renal mass showing classic radiological appear-
ment of the renal mass. While renal mass biopsy is usually ance of an angiomyolipoma.
well-tolerated, it is an invasive procedure associated with Renal mass biopsy should be offered to patients when
risks. Patients must be counselled on the rationale for a the biopsy result may alter the management approach they
renal mass biopsy, how the results (malignant, non-malig- select. For some patients, the results of a biopsy, malignant
nant, non-diagnostic) may alter their management choices, or benign, are unlikely to alter the management options they
the side effects of a biopsy, and alternatives management select. For very elderly, highly comorbid, or frail patients, the
options. Patient counselling should encourage shared deci- competing risks of mortality from other causes outweigh the
sion-making and a patient-centered approach to care. risk of death from small renal mass even if a biopsy reveals
A renal mass biopsy provides three possible histologic- RCC. In these patients, whom active surveillance or watch-
al results; malignant, benign, or non-diagnostic. When a ful waiting will be recommended irrespective of the biopsy
renal mass biopsy is malignant, the physician should discuss outcome, renal mass biopsy should not be performed.
management options with the patient. When a renal mass For healthy patients with a long life expectancy and a
biopsy is reported benign, patients should be monitored with low risk of significant morbidity from definitive treatment,
imaging to ensure there are no concerning interval changes it is important to discuss the role of renal mass biopsy and
in the size or appearance of the mass. The diagnostic accur- how the results may impact their treatment choices. Some
acy of renal mass biopsy at experienced centers is good, patients will prefer definitive management because they are
however, there is still the possibility of a false negative test unwilling to accept any uncertainty after a renal mass biopsy
result (i.e., benign biopsy reported when a malignancy is or because they want to avoid a long period of imaging
present). The false negative rate of renal mass biopsies in surveillance. In these patients, proceeding with definitive
one Canadian series was 3.5%; however, most renal mass treatment is recommended and a renal mass biopsy should
biopsy series do not report the false negative rate, as masses not be performed.
with a benign biopsy are not removed. Therefore, a range Angiomyolipomas (AMLs) are benign renal masses that
of false negative rates may be expected based on center contain fat, smooth muscle, and blood vessels. The major-
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experience and patient selection. 5,36 One example of a par- ity of these lesions contain abundant amounts of fat visible
ticularly challenging diagnosis is differentiating oncocytoma on imaging, making the diagnosis of AML on cross-section-
and chromophobe RCC. A reasonable approach to monitor- al imaging reliable. Fat-containing RCCs are rare. Renal
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ing after a benign renal mass biopsy would include imaging masses with classic radiological features of an AML do not
with an ultrasound or computed tomography (CT) scan at require a renal mass biopsy to confirm the diagnosis.
six months and 12 months after the renal mass biopsy. The
followup imaging schedule can then be adapted based on Renal mass biopsy of cystic renal masses
patient factors and mass characteristics, such as the patient
age, mass size, and growth pattern after the first year. 12. Biopsy of cystic renal masses may be considered if there
For patients with a non-diagnostic renal mass biopsy, is a significant solid component amenable to biopsy.
management may include monitoring, repeat biopsy attempt, Renal masses without a solid component should not be
or proceeding directly to definitive treatment. After a non- biopsied due to low diagnostic yield.
diagnostic renal mass biopsy, patients should be counselled The use of renal mass biopsy for cystic and solid renal
on the benefits and harms of a repeat biopsy. If it is felt masses is different. First, the diagnostic yield is lower for
the results of repeat biopsy may alter management, repeat cystic tumors, given the large fluid-filled area of the mass. 7,12
biopsy may be offered. Second, the risk of puncture and spillage of the cystic fluid
is a concern. Finally, in comparison to matched solid-
12
Patients in whom renal mass biopsy should not be enhancing renal masses, renal masses with a large cystic
recommended component are associated with a less aggressive natural
39,40
Therefore, unless
history and a lower risk of metastases.
there is a solid, nodular, enhancing component in the cystic
9. Renal mass biopsy should not be recommended to renal mass, these masses should not routinely be biopsied.
patients in whom active surveillance or watchful wait-

380 CUAJ • December 2019 • Volume 13, Issue 12