Diagnostic Ultrasound - Abdomen and Pelvis

Adrenal Cyst
TERMINOLOGY
Definitions
• Descriptive term for simple or complex cystic lesion in
adrenal gland
IMAGING
General Features
• Best diagnostic clue
○ Rounded, uni-/multilocular, thin-walled, suprarenal cyst
• Location
○ Unilateral > bilateral (8-10%)
• Size
○ Majority ≤ 5 cm (50%), up to 20 cm
Ultrasonographic Findings
• Grayscale ultrasound
○ Well-defined, anechoic or hypoechoic, uni-/multilocular;
with thin wall and posterior acoustic enhancement
○ Low-level internal echoes, hyperechoic foci (calcification),
fluid-fluid levels, and septations suggest recent
hemorrhage
○ Complicated cyst, ≥ 5 cm size, internal echogenicity or
thick wall (≥ 3 mm): ↑ concern for malignancy
• Color Doppler shows no internal flow
CT Findings
• NECT
○ Well circumscribed with thin wall, homogeneous low
density (water or near-water density < 20 HU)
○ Higher or mixed attenuation cyst contents →
hemorrhage, intracystic debris, crystals
○ Calcification seen in 15-30%
– Rim-like or nodular (51-69%), centrally along
septations (19%), punctate within intracystic
hemorrhage (5%)
• CECT: No central enhancement ± wall enhancement
MR Findings
• Uncomplicated: Uniformly T1 hypointense, T2 hyperintense
• Hemorrhage: Variable T1 hyperintensity
• Centrally nonenhancing on T1WI C+
Imaging Recommendations
• Best imaging tool
○ US for initial screening and follow-up
○ CT and MR for further characterization
DIFFERENTIAL DIAGNOSIS
Necrotic Adrenal Tumor
• Primary: Pheochromocytoma or adrenal carcinoma
• Metastatic tumor (e.g., melanoma metastases)
• Cystic neuroblastoma in appropriate age group (rare)
• Complex wall with heterogeneous contents and enhancing
components
Adjacent Cystic Lesions
• Hepatic or renal cyst; pancreatic tail pseudocyst, splenic
artery pseudoaneurysm, splenic varices, GI duplication cyst;
gastric diverticulum
• Multiplanar CT or MR can help better characterize origin
Adrenal Adenoma
• Well defined and homogeneous with density < 30 HU on CT
• Shows avid enhancement without wall
PATHOLOGY
General Features
• Etiology
○ Endothelial lining (~ 45%): Lymphangioma (majority) and
hemangioma
○ Epithelial lining (~ 9%): True simple cyst; types include
congenital glandular or retention cyst, embryonal cyst,
cystic adenoma, or mesothelial inclusion cyst
○ Pseudocyst (~ 39%): Prior hemorrhage or infarction
○ Parasitic cyst (~ 7%): Usually due to disseminated
Echinococcus granulosus infection
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Usually clinically silent
○ Abdominal or flank pain due to mass effect
• Other signs/symptoms
○ Retroperitoneal hemorrhage
○ Hypertension associated with adrenal cyst
Demographics
• Age
○ 3rd to 6th decade of life
• Epidemiology
○ Uncommon with autopsy incidence of 0.073%
○ Imaging prevalence of about 1%
Natural History & Prognosis
• Complications: Hypertension, infection, rupture with
retroperitoneal hemorrhage, intracystic hemorrhage
• Prognosis: Excellent
• Increase in size over time frequently seen with benign cysts
and is not indicative of malignancy
Treatment
• Usually conservative management: No standard follow-up
imaging recommendations
○ Hormonal work-up to assess activity of lesion
• Treatment reserved for cysts with malignant features, > 5
cm, or in symptomatic patients with endocrine
abnormalities or complications
○ Ultrasound-guided percutaneous cyst aspiration; ±
injection of sclerosing agent
– Cyst-fluid analysis may yield adrenal steroids or
cholesterol: Diagnostic of adrenal cyst
– Therapeutic for cyst without malignant features
○ Surgical resection; laparoscopic approach
SELECTED REFERENCES
1. Lattin GE Jr et al: From the radiologic pathology archives: adrenal tumors
and tumor-like conditions in the adult: radiologic-pathologic correlation.
Radiographics. 34(3):805-29, 2014
2. Ricci Z et al: Adrenal cysts: natural history by long-term imaging follow-up.
AJR Am J Roentgenol. 201(5):1009-16, 2013
Diagnoses: Adrenal Gland
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