Diagnostic Ultrasound - Abdomen and Pelvis

Pheochromocytoma
600
Diagnoses: Adrenal Gland
Adrenocortical Carcinoma
• Rare; aggressive; large, unilateral, heterogeneous solid with
necrosis; hemorrhage ± calcification
• ↑ T1 and ↓ T2 signal (as with "classic"
pheochromocytomas)
• Aggressive, often with IVC extension
Adrenal Neuroblastoma
• Large pediatric adrenal mass; calcification (80-90%)
Adrenal Granulomatous Infection
• TB, histoplasmosis, other fungal diseases; usually bilateral
○ Acute (hypoechoic masses) or chronic (small & calcified)
PATHOLOGY
General Features
• Associated abnormalities
○ Majority are sporadic
○ 25% have autosomal dominant gene mutation
– Multiple endocrine neoplasia, type II (MEN2)
□ MEN2 mutation; 50% have pheochromocytoma
□ Medullary thyroid carcinoma; hyperparathyroidism;
neuromas and marfanoid habitus
– von Hippel-Lindau (VHL) disease
□ VHL tumor suppressor gene, 10-20% risk
□ Multiple benign and malignant tumors
– Neurofibromatosis, type I
□ Rare cause of pheochromocytomas (1% risk)
□ Cutaneous/plexiform neurofibromas, optic nerve
gliomas, peripheral nerve sheath tumors,
gastrointestinal stromal tumor
– Pheochromocytoma-paraganglioma syndromes
□ Mutations of succinate dehydrogenase gene family
(SDHB and SDHD)
□ ↑ incidence of extraadrenal tumors and head/neck
paragangliomas
□ 50% risk of malignant pheochromocytomas
• Most are benign; 10% are malignant
○ Diagnosis of malignancy is based solely on presence of
direct local tumor invasion or metastatic disease
○ Extraadrenal paragangliomas are more likely to be
malignant
Gross Pathologic & Surgical Features
• Range of appearances: Small, well-circumscribed, yellowtan
lesion confined to adrenals; large, hemorrhagic, cysticnecrotic
masses
Microscopic Features
• Predominantly chromaffin cells; occasionally spindle cells
are dominant feature
○ Term pheochromocytoma refers to dusky color of cells
stained with chromium salts
• No single histologic feature of pheochromocytoma
consistently predicts malignancy
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Majority are asymptomatic; symptoms may be episodic
or paroxysmal
○ Classic triad (arises from adrenergic excess)
– Paroxysmal headache, palpitations, sweating
– 90% specific but uncommon (only present in 10.0-
36.5% of patients)
• Other signs/symptoms
○ Hypertensive crisis: Palpitations, tremors, arrhythmias,
pain, myocardial infarction
• Lab data
○ Tumors typically secrete norepinephrine > epinephrine
○ ↑ levels of 24-hour urine-fractionated metanephrines
– 90-97% sensitivity; 69-98% specificity
Demographics
• Age
○ Sporadic cases, 3rd and 4th decades (mean age: 44 years)
○ Hereditary cases (mean age: 25 years)
○ 10% are found in children
• Gender
○ Slight female predilection (M:F = 1:1.4)
• Epidemiology
○ Incidence (exact unknown): Estimated at 2-8 cases/1
million people/year
– 0.1-0.6% of hypertensive adults
○ Majority of pheochromocytomas are likely asymptomatic
(incidentalomas)
– Autopsy occurrence rates 10-17%
Natural History & Prognosis
• Hypertensive crises and cardiovascular complications ↑
morbidity/mortality
• Prognosis
○ Noninvasive and nonmetastatic: Typically favorable
– Postoperatively: 50% have persistent hypertension;
16% recur within 10 years of resection
○ Malignant tumors: 54% 5-year survival rate
Treatment
• Symptomatic therapy: α-adrenergic blockade and calcium
channel antagonists
• Laparoscopic resection/debulking for both benign and
malignant tumors
• Adjuvant therapy (malignant tumors): I-131 MIBG therapy ±
chemotherapy (cyclophosphamide, vincristine, dacarbazine)
DIAGNOSTIC CHECKLIST
Consider
• Imaging characteristics can mimic other diagnoses; labs
essential for diagnosis
Image Interpretation Pearls
• Extraadrenal tumors arise anywhere along sympathetic
ganglia (neck to bladder); include in search pattern
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. Leung K et al: Pheochromocytoma: the range of appearances on ultrasound,
CT, MRI, and functional imaging. AJR Am J Roentgenol. 200(2):370-8, 2013
3. Raja A et al: Multimodality imaging findings of pheochromocytoma with
associated clinical and biochemical features in 53 patients with histologically
confirmed tumors. AJR Am J Roentgenol. 201(4):825-33, 2013