KEY FACTS
Terminology
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Rare catecholamine-secreting tumor arising from chromaffin cells of adrenal medulla
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Termed paraganglioma if extraadrenal
Imaging
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Best diagnostic clue
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Adrenal mass in setting of clinical symptoms or biochemical abnormality
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Paroxysmal headache, palpitations, sweating
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↑ levels of 24-hr urine-fractionated metanephrines
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” Imaging ” chameleon
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Commonly solid and hypervascular ± cystic change, necrosis, and calcification
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Can be purely cystic
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1st-line : CT or MR
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Size: Up to 15 cm (typically 3-5 cm)
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Variable appearance: Solid (75%) > solid/cystic or cystic
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Larger tumors: Solid; homogeneous (46%) or heterogeneous (54%)
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Can be predominantly cystic due to chronic hemorrhage and necrotic debris (fluid-fluid level)
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Always evaluate bladder wall, renal hilum, and organ of Zuckerkandl at origin of inferior mesenteric artery
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Hypervascular
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Ultrasound may detect adrenal masses but is limited for extraadrenal disease
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68Ga-DOTATATE PET/CT or I-123 MIBG : Most specific modalities for localization and detection of metastatic/recurrent disease
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US : Comparable sensitivity to CT for detection of adrenal disease; poor detection of extraadrenal tumors
Top Differential Diagnoses
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Adrenal adenoma
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Adrenal metastases or lymphoma
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Adrenocortical carcinoma
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Adrenal neuroblastoma
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Adrenal granulomatous infection
Pathology
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25% have autosomal dominant gene mutation
Clinical Issues
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Classic triad (arises from adrenergic excess): Paroxysmal headache, palpitations, sweating
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Majority are asymptomatic; symptoms may be episodic or paroxysmal
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Hypertensive crisis: Palpitations, tremors, arrhythmias, pain, myocardial infarction
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Hereditary cases (mean age: 25 years)
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Sporadic cases: 3rd and 4th decades (mean age: 44 years)
Diagnostic Checklist
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Remembered as ” rule of 10s ”
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10% extraadrenal (paraganglioma)
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10% bilateral (suggesting hereditary disease)
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10% pediatric (also suggests hereditary disease)
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10% contain calcification
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10% malignant (higher for extraadrenal cases)
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25% familial (previously thought to be 10%)
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, moderate in size, with a well-circumscribed margin and solid appearance. Note hypervascularity 
of the mass, which commonly results in necrosis and cystic change.
, which was proven to be a pheochromocytoma. It is hyperechoic to the renal cortex 
.
