Editing Adrenal: Malignant Tumours (section)

==== Imaging ====

* '''In incidentally detected adrenal tumors, size is a relative indicator of malignancy'''
** '''Risk of malignancy based on tumour size:'''
*** '''< 4 cm: 5%'''
*** '''> 4 cm: 10%'''
*** '''> 6 cm: 25%'''
*** Given the relationship between size and malignancy, '''it is currently recommended that adrenal tumors > 4-6 cm be surgically excised'''
** ACCs tend to be larger than benign adrenal tumors, with an average size of 10-12 cm on presentation
* '''Radiographic characteristics of ACCs on CT imaging (5):'''
*# '''Irregular borders'''
*# '''Heterogenous enhancement'''
*# '''Increased enhancement (mean 39 HU) compared to adenoma (8 HU)'''
*# '''Calcifications'''
*# '''Necrotic areas with cystic degeneration'''
* '''MRI'''§
** '''Normal adrenal gland'''
*** '''TI: uniform intermediate signal intensity that is slightly less intense than that of the liver and renal cortical tissue'''
*** '''T2: difficult to distinguish from retroperitoneal adipose tissue because of the presence of intracellular lipid with the gland'''
** '''Myelolipoma'''
*** '''T1: bright'''
*** '''T2: intermediate'''
** '''ACCs'''
*** '''T1: isointense relative to the liver or spleen'''
*** '''T2: intermediate to increased intensity'''
*** '''Marked contrast uptake on gadolinium-enhanced images'''
** '''Pheochromocytoma'''
*** '''Classically, bright signal intensity on T2-weighted imaging''' (best seen on fat suppression sequences)—termed the “light bulb” sign—was believed to be diagnostic. It is now clear that '''this imaging characteristic is neither specific nor sensitive enough to secure a diagnosis and must be interpreted with caution'''