Simple or complex cystic lesion in adrenal gland

Well-defined, round, typically unilocular, thin-walled, suprarenal cyst

Anechoic or hypoechoic lesion with thin wall and posterior acoustic enhancement

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  Low-level internal echoes, calcification, fluid-fluid levels, and septations suggest recent hemorrhage

CT: Nonenhancing, thin-walled, homogeneous, low-density lesion with attenuation values < 20 HU

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  Higher or mixed attenuation cyst contents → hemorrhage, intracystic debris, crystals; ± calcification

MR: Nonenhancing with uniform low T1, high T2 SI

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  Hemorrhage shows variable T1 signal

Concerning features: Complicated cyst, ≥ 5 cm, internal echogenicity, or thick wall (≥ 3 mm) → suspect malignancy

Color Doppler shows no internal flow

May be initially detected and characterized by ultrasound; ultrasound can be used for follow-up

Imaging recommendation

CT and MR for further characterization if complex

Complicated cyst, ≥ 5 cm, internal echogenicity or thick wall (≥ 3 mm): ↑ concern for malignancy

Adjacent cystic lesions

Adrenal adenoma

Necrotic adrenal tumor

Endothelial lining (~ 45%): Lymphangioma (majority) and hemangioma

Pseudocyst (~ 39%): Prior hemorrhage or infarction

Epithelial lining (~ 9%): True simple cyst

Parasitic cyst (~ 7%): Usually due to disseminated Echinococcus granulosus infection

Typically clinically silent

Abdominal or flank pain due to mass effect or cyst rupture

Often increases in size over time; not indicative of malignancy

Usually conservative management: No standard follow-up imaging recommendations

Treatment reserved for cysts with malignant features, > 5 cm, or in symptomatic patients with endocrine abnormalities or complications

Due to posttraumatic cyst rupture

Adrenal cysts are avascular; optimize Doppler settings to avoid misdiagnosis