Editing Benign Kidney Tumours (section)

=== Management ===
* '''<span style="color:#ff0000">Based on Bosniak classification</span>[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5365391/]'''
** '''<span style="color:#ff0000">Bosniak I and II</span>'''
*** '''<span style="color:#ff0000">Follow-up not warranted</span>'''
**** '''Majority will grow over time'''; growth should not necessarily be considered a sign a malignancy
**** Transformation into a more complex cyst is rare
*** '''<span style="color:#ff0000">Intervention only warranted if the cyst becomes symptomatic</span>''' (bleeding, recurrent infection or pain)
**** '''Treatment options:'''
****# '''Percutaneous management (aspiration +/- sclerotherapy)'''
****# '''Cyst decortication'''
****# '''Surgical resection'''
**** Percutaneous cyst decompression may be considered prior to offering definitive treatment as a means to confirm that the source of symptoms are cyst-related
** '''<span style="color:#ff0000">Bosniak IIF</span>'''
*** '''≈15% of these category IIF cysts will progress in complexity''' (to Bosniak category III or IV)
*** '''<span style="color:#ff0000">Should be followed with imaging</span>'''
**** '''<span style="color:#ff0000">Contrast-enhanced CT scan or MRI (not US) every 6 months for the first year. Cases without progression should be followed annually for at least 5 years</span>'''
** '''<span style="color:#ff0000">Bosniak III/IV</span>'''
*** '''<span style="color:#ff0000">Surgical excision is generally suggested</span>'''
*** '''<span style="color:#ff0000">Bosniak III</span>'''
**** '''Given the low metastatic potential of cystic RCC, the panel feels that reduced surgical margins and controlled cyst decompression (if required) can be performed with low risk of tumour recurrence'''
**** '''For the same reason, active surveillance and thermal-ablation therapies (see below) may also be considered as appropriate treatment alternatives in select cases'''
*** '''<span style="color:#ff0000">Bosniak IV</span>'''
**** '''Most of these malignant cysts are thought to have low metastatic potential and thus, more conservative management may be safely considered in select cases'''
*** '''<span style="color:#ff0000">2017 AUA Localized RCC Guideline:</span>'''
**** '''<span style="color:#ff0000">AS is an option as initial management, especially those <2cm</span>'''
**** '''AS/expectant management should be prioritized when the anticipated risk of intervention or competing risks of death outweigh the potential oncologic benefits of active treatment'''
**** For patients in whom the
***** Risk/benefit analysis for treatment is equivocal and who prefer AS, physicians should repeat imaging in 3-6 months to assess for interval growth and may consider RMB for additional risk stratification.
***** Anticipated oncologic benefits of intervention outweigh the risks of treatment and competing risks of death, physicians should recommend active treatment. In this setting, AS with potential for delayed intervention may be pursued only if the patient understands and is willing to accept the associated oncologic risk.

* '''Role of active surveillance for suspected cystic RCC'''
** '''The vast majority of cystic RCCs are multilocular cystic RCCs (mcRCC)''' though all RCC subtypes may present in a predominantly cystic form
*** '''Cystic RCCs need to be distinguished from solid renal masses with necrotic components, which behave more aggressively'''
** '''<span style="color:#ff0000">mcRCCs have low malignant potential</span>'''
*** '''Better cancer-specific and overall survival compared with solid RCCs'''
**** '''There has yet to be a report demonstrating metastases or recurrence of mcRCCs.'''
**** One potential explanation for this indolent behaviour is that the majority of mcRCCs tumour volume is fluid and therefore the actual tumour burden is much lower when compared to similar sized solid tumours.
*** To reflect this indolent behaviour, the International Society of Urological Pathology (ISUP) now recommends calling these lesions multilocular cystic renal neoplasm with low malignant potential
*** As the outcomes of these tumours do not seem to be influenced by the overall lesion size, some have even suggested to abandon the current pathological T staging for mcRCC and to reassigned them a new stage called pT1c (c for cystic).
** '''Given their relatively indolent behaviour, there is emerging evidence suggesting that these lesions (especially Bosniak classification III) can be safely managed by active surveillance'''
*** If active surveillance is considered, consider abdominal imaging every 6 months for the first 2 years, followed by yearly imaging thereafter, if the lesion is stable.
** '''<span style="color:#ff0000">Triggers for intervention on active surveillance for suspected cystic RCC are yet to be clearly defined and validated, but may include (3):</span>'''
**# '''<span style="color:#ff0000">Progression from Bosniak III to IV</span>'''
**# '''<span style="color:#ff0000">Growth of solid nodule > 3 cm</span>'''
**# '''<span style="color:#ff0000">Fast-growing nodule</span>'''
* '''Thermal-ablation therapies (RFA, cryotherapy)'''
** '''Given the limited data, RFA should be limited to patients with small Bosniak category III and IV cysts who are poor operative candidates and in whom active surveillance is not being considered'''
** '''The role of cryotherapy in the management of Bosniak III or IV cysts is not well-defined,''' only a few cases reports in the literature