Diagnostic Ultrasound - Abdomen and Pelvis

Pheochromocytoma
Diagnoses: Adrenal Gland
TERMINOLOGY
• Definition: Rare catecholamine-secreting tumor arising
from chromaffin cells of adrenal medulla
• Termed paraganglioma if extraadrenal
IMAGING
• Best diagnostic clue
○ Adrenal mass in setting of clinical symptoms or
biochemical abnormality
– Paroxysmal headache, palpitations, sweating
– ↑ levels of 24-hr urine-fractionated metanephrines
• "Imaging chameleon": Variable US/CT/MR appearance;
mimics other lesions
○ Commonly solid and hypervascular ± cystic change,
necrosis, and calcification
○ Can be purely cystic
• First-line: CT or MR
• US: Comparable to CT in detecting adrenal tumors; limited
for extraadrenal disease
KEY FACTS
• I-123 MIBG: For extraadrenal, metastatic, or recurrent
disease
TOP DIFFERENTIAL DIAGNOSES
• Adrenal adenoma
• Adrenal metastases or lymphoma
• Adrenocortical carcinoma
• Adrenal neuroblastoma
• Adrenal granulomatous infection
DIAGNOSTIC CHECKLIST
• Remembered as "rule of 10s"
○ 10% extraadrenal (paraganglioma)
○ 10% bilateral (suggesting hereditary disease)
○ 10% pediatric (also suggests hereditary disease)
○ 10% contain calcification
○ 10% malignant (higher for extraadrenal cases)
○ 25% familial (previously thought to be 10%)
(Left) Graphic shows a typical
pheochromocytoma ,
moderate in size, with a wellcircumscribed
margin and solid
appearance. Note
hypervascularity ſt of the
mass, which commonly results
in necrosis and cystic change.
(Right) Transverse
transabdominal ultrasound
demonstrates a wellcircumscribed,
homogeneous
hypoechoic adrenal mass ſt.
The appearance is nonspecific,
but the patient presented with
elevated catecholamines and
hypertensive urgency,
suggesting a diagnosis of
pheochromocytoma.
(Left) Longitudinal
transabdominal ultrasound
shows a well-demarcated,
solid right adrenal mass ,
which was proven to be a
pheochromocytoma. It is
hyperechoic to the renal
cortex . (Right) Transverse
transabdominal ultrasound of
a right adrenal
pheochromocytoma shows a
large, well-defined echogenic
mass with an anechoic
cystic area representing
necrosis .
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