Editing Kidney Cancer: Diagnosis and Evaluation (section)

=== Renal mass biopsy ===

==== Rationale ====

* '''≈20-30% of clinically localized''' '''solid, enhancing, clinical T1 renal masses are benign'''
** The smaller the tumour size, the more likely to be benign.
*** Risk of malignancy increases 30%/cm increase in tumour size
** '''Young to middle-age women, in particular, are more likely to have benign pathology''', as high as 40% in some series.
*** Some benign renal masses, such as cystic nephroma and atypical AML, may be influenced by the hormonal milieu and are thus more common in women
** Most benign clinical T1 renal masses are oncocytomas or atypical AMLs.

==== Test performance characteristics ====
* '''A diagnosis of malignancy or RCC on RMB is highly reliable'''
* '''Mean diagnostic rate: 92%''' (8% non-diagnostic rate)[https://pubmed.ncbi.nlm.nih.gov/26323946/]
**'''Pooled sensitivity: 96.7%'''
**'''Pooled specificity: 94.4%'''
**Pooled positive predictive value: 98.8%
**Pooled negative predictive value: 80.8%
*'''Histologic concordance: 90%[https://pubmed.ncbi.nlm.nih.gov/26323946/]'''
*'''Grade concordance: 62%[https://pubmed.ncbi.nlm.nih.gov/26323946/]'''
*PET scanning coupled with administration of radioactively labeled anti–CA-IX monoclonal antibody has been reported as an alternative to RMB

==== Limitations (4) ====
#'''A benign biopsy must be distinguished from a non-diagnostic biopsy (renal parenchyma or connective tissues) result.'''
#*Non-diagnostic rate of renal mass biopsy is approximately 14%, which can be substantially reduced with repeat biopsy
#'''A benign biopsy may not always correlate with benign histology.'''
#*Due to the imperfect nature of renal mass biopsy, patients with benign renal mass biopsy may warrant follow-up.
# '''Grade concordance from biopsy to surgically resected tissue is imperfect.'''
#'''Oncocytic neoplasms may represent a diagnostic dilemma.'''

===== Indications =====

====== CUA ======
* '''[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8932428/ 2022 CUA Guidelines on Management of Small Renal Masses]'''
** '''<span style="color:#ff0000">Should be offered when the result of the biopsy will influence management'''

====== AUA ======

* [https://pubmed.ncbi.nlm.nih.gov/28479239/ '''2021 AUA Guidelines on Renal Mass and Localized Renal Cancer''']
** Currently has an adjunctive role in the diagnosis and risk stratification of patients with renal masses suspicious for RCC
** '''<span style="color:#ff0000">Consider biopsy when a mass is suspected to be hematologic, metastatic, inflammatory, or infectious.</span>'''
*** See [[Management of Localized and Locally Advanced Disease|Kidney Cancer: Non-Renal Cell Carcinoma Renal Malignancies Chapter Notes]]
*** If metastatic cancer is confirmed, systemic treatment is typically prioritized.
*** Index of suspicion for a non-neoplastic process, such as renal sarcoidosis, abscess, or focal pyelonephritis, should be increased in patients presenting with signs and symptoms consistent with an infectious or inflammatory condition or those with a prior history of recurrent infections or autoimmune disease
** '''<span style="color:#ff0000">Should be obtained if it will influence management</span>'''
***'''<span style="color:#ff0000">NOT required for (2):</span>'''
***#'''<span style="color:#ff0000">Young or healthy patients who are unwilling to accept the uncertainties associated with RMB</span>'''
***#'''<span style="color:#ff0000">Older or frail patients who will be managed conservatively independent of RMB findings</span>'''

===== Contraindications =====
*'''<span style="color:#ff0000">Biopsy or aspiration of cystic renal masses is generally not recommended, unless there is a targetable solid component, due to (2):[https://pubmed.ncbi.nlm.nih.gov/28479239/]</span>'''***#'''<span style="color:#ff0000">Concerns regarding tumor spillage</span>'''
*#'''<span style="color:#ff0000">High likelihood of obtaining a non-informative result due to sampling error</span>'''

===== Technique =====
*May be performed under CT or US guidance
* '''Multiple core biopsies are preferred over fine needle aspiration[https://pubmed.ncbi.nlm.nih.gov/28479239/]'''
** At least 2-3 cores being obtained with a 16-18 gauge needle to optimize diagnostic yield

===== Complications =====
*'''Overall complication rate: 8%[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8932428/]'''
**Vast majority of these complications reported as Clavien-Dindo <2 (>99%)
*'''Most common (5):'''
*# '''Renal hematoma''' (4.9%)
*# '''Clinically significant pain''' (1.2%)
*# '''Gross hematuria''' (1.0%)
*# '''Pneumothorax''' (0.6%)
*# '''Hemorrhage requiring transfusion''' (0.4%)
* '''No reported cases of tumor seeding using contemporary techniques'''[https://pubmed.ncbi.nlm.nih.gov/17561170/ §]