Editing CUA: Surgical Management of RCC (2014) (section)

===== '''Pretreatment prediction of tumour histology''' =====

* '''Nomograms and Classification trees have been developed and may be used to predict pretreatment histology of renal masses less than 4 cm in diameter.'''
* '''Biopsy of the localized renal mass'''
** '''Biopsy of SRMs for histologic characterization is an option and may guide treatment decisions'''
*** Biopsy has a mean diagnostic rate of 83%. Histology concordance is good (73-98%), Fuhrman grade concordance is not robust (32-70%)
*** In the case of a non-diagnostic initial biopsy, it may be expected that a diagnosis can be made with repeat biopsy, and that the rate of malignancy remains high.
*** Indeterminate initial biopsy should not be taken as reassurance regarding the malignant potential of the mass.
*** It is essential to identify tumour histology in the setting of metastatic disease, both to confirm that metastatic sites represent tumour spread (and not a second primary tumour) and to classify the histologic subtype as a guide to systemic therapy. In many cases in which cytoreductive nephrectomy will have been performed, the primary histology is known and widespread metastatic disease can comfortably be assumed to be similar. If cytoreductive nephrectomy is not performed prior to planned initiation of systemic therapy, percutaneous biopsy may help to guide therapy.
*** In the setting of oligometastatic disease, the link between primary and secondary masses cannot be assumed reliably. Limited data are available with regards to the role of percutaneous biopsy in this setting.
** '''Biopsy of a renal mass or metastatic site in the setting of metastatic disease is important in guiding systemic therapy.'''
** '''In patients undergoing cytoreductive nephrectomy before systemic therapy, or surgical resection of metastatic site, a biopsy may not be necessary.'''
** '''Percutaneous biopsy is associated with a low risk of complications.'''
** '''Biopsy should be reserved for patients in whom the results might change management.'''