Adrenal cyst

Last revised by Daniel J Bell on 30 May 2023

Adrenal cysts are rare lesions that are usually found incidentally on imaging performed for other reasons. 

Adrenal cysts are reported to be rare with an incidence of <1% 1

Patients can present with pain or swelling, although a significant portion (~40%) are incidental findings 1,3. Functional adrenal cysts are very rare 7.

Adrenal cysts can be divided into four categories 1-3:

Usually thin-walled cystic lesions with anechoic content and posterior beam enhancement. Internal mobile echoes might be seen. 

Small adrenal cysts may be difficult to differentiate from adrenal adenomas on unenhanced CT as they may both have densities in the pure fluid range, i.e. -10 to +10. However on post-contrast CT adrenal adenomas tend to enhance, whereas cysts do not 5.  

MRI is commonly reserved for those equivocal cases on CT and confirms fluid within the cyst (bright T2 signal) 6

In 1966, the pathologist Dale G Foster subclassified adrenal cysts into four main types based on histopathological evaluation of 115 cases: epithelial cysts, parasitic cysts, especially hydatid, pseudocysts and endothelial cysts. In this series, endothelial cysts were the commonest type. Although other studies since have found pseudocysts to be more common 7.

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Cases and figures

  • Case 1: adrenal pseudocyst
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  • Case 2: adrenal epithelial cyst
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  • Case 3: re-endothelialised hematoma
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  • Case 4
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  • Case 5: hemorrhagic cyst
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  • Case 6
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  • Case 7
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  • Case 8
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