Diagnostic Ultrasound - Abdomen and Pelvis

Adrenal Adenoma
Diagnoses: Adrenal Gland
TERMINOLOGY
• Synonym: Adrenocortical adenoma
IMAGING
• May suggest diagnosis based on US; however, no specific
sonographic features distinguish adenomas from other
adrenal lesions
• US: Typically small, smoothly marginated, homogeneous,
and hypoechoic
○ Size is particularly important: Smaller adrenal lesions
tend to be benign; > 4 cm more likely malignant
○ Size stability over 12 months supports benignity
• CT and MR: Best imaging tool
○ Lipid-rich adenomas are best characterized with NECT or
chemical shift MR
○ Lipid-poor adenomas can be characterized with CECT
with 10-min delayed-phase imaging
KEY FACTS
CLINICAL ISSUES
• Adrenal adenoma may be detected due to
hyperfunctioning activity
○ Cushing syndrome, Conn syndrome, or virilization
syndromes
• More commonly detected as incidental finding
○ Increased detection in recent years due to greater
imaging utilization
DIAGNOSTIC CHECKLIST
• Benign vs. malignant: Consider size and stability
○ Comparison with any available prior imaging may help to
establish stability over 12 month period and avoid
unnecessary additional testing
• Attenuation < 10 HU on NECT → lipid-rich adenoma
• Signal drop on T1 out-of-phase MR → lipid-rich adenoma
• > 60% absolute washout on 10-min delayed-phase CECT →
lipid-rich and lipid-poor adenomas
(Left) Graphic shows a small,
homogeneous, solid nodule ſt
arising from the peripheral
adrenal gland. Note the oval
shape and smooth margin
typical of an adrenal
adenoma. (Right) Longitudinal
transabdominal US shows a
well-circumscribed,
homogeneous solid mass ſt
above the right kidney st.
(Left) Transverse
transabdominal US shows a
well-demarcated,
homogeneous right adrenal
mass ſt, which is mildly
hyperechoic relative to the
liver. (Right) Transverse color
Doppler US in the same
patient shows that the lesion
ſt is relatively hypovascular.
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