Editing Benign Kidney Tumours (section)

=== Diagnosis and Evaluation ===

==== History and Physical Exam ====

*'''Clinical Presentation'''
** '''<span style="color:#ff0000">Spontaneous perirenal hemorrhage</span>'''
*** '''<span style="color:#ff0000">Renal neoplasm most commonly associated with spontaneous perirenal hemorrhage, closely followed by RCC</span>'''
*** Aneurysmal dilation is found in 50% of AMLs; size of aneurysm correlates with risk of rupture
*** '''Wunderlich syndrome, which is a massive spontaneous non-traumatic retroperitoneal hemorrhage (from any cause), is the most significant complication of AML'''
*** '''<span style="color:#ff0000">Pregnancy increases risk of AML hemorrhage</span>'''

==== Imaging ====
* '''<span style="color:#ff0000">The only benign renal tumour that is confidently diagnosed on imaging</span>'''
** '''<span style="color:#ff0000">Presence of fat (≤-20 HFU) within a renal lesion is considered a diagnostic landmark</span>'''
*** '''<span style="color:#ff0000">Other lesions that can contain fat (2):</span>'''
**** '''<span style="color:#ff0000">Liposarcoma</span>'''
***** '''Should be considered in the differential of a fat-containing retroperitoneal tumour'''
*****Can distinguish from RCC by whether mass originates from kidney or retroperitoneum, the latter of which may displace kidney
**** '''<span style="color:#ff0000">Fat-containing RCC</span>'''
***** '''In RCC, the fat is thought to be a reactive process related to tumor necrosis.'''
*** '''<span style="color:#ff0000">≈5% of AML’s are fat poor</span>'''
**** '''<span style="color:#ff0000">Fat-poor AML can be difficult to distinguish from RCC</span>'''
**** '''<span style="color:#ff0000">Calcification is virtually never seen in association with AML</span>'''
***** '''<span style="color:#ff0000">Clinical implication: presence of fat with calcification is suggestive of RCC</span>'''
** '''MRI can be used in difficult cases when the lesion has minimal fat'''
***'''A T2-weighted image with fat suppression is most likely to identify macroscopic fat and confirm the diagnosis of an angiomyolipoma (AML).'''

==== Other ====
* '''Biopsy'''
** '''Consider biopsy if imaging findings equivocal'''