Overview
Definition:
Adrenal incidentalomas are adrenal masses discovered incidentally during imaging performed for unrelated reasons, not suspected clinically based on symptoms of hormone excess
In adolescents, their prevalence is lower than in adults, but evaluation is crucial due to potential for malignancy and endocrine activity.
Epidemiology:
The exact incidence in adolescents is not well-established, but it is significantly lower than in adults
Studies in adult populations report prevalence rates ranging from 1% to 10%
Factors like increasing use of cross-sectional imaging contribute to detection
Pediatric studies are limited, but incidentalomas are more common in older adolescents.
Clinical Significance:
Adrenal incidentalomas in teens warrant careful evaluation to rule out potentially serious conditions such as adrenal malignancy (carcinoma), functional adrenal tumors (producing excess hormones like cortisol, aldosterone, or catecholamines), or pheochromocytoma
Early detection and appropriate management can prevent long-term morbidities and improve outcomes.
Diagnostic Approach
History Taking:
Detailed history focusing on symptoms of hormonal excess: Cushingoid features (weight gain, central obesity, striae, moon facies), hypertension, hypokalemia (suggestive of hyperaldosteronism), palpitations, headaches, sweating (suggestive of pheochromocytoma), or signs of virilization/precocious puberty
Family history of endocrine disorders or adrenal tumors is important
Review of imaging indications and incidental findings.
Physical Examination:
Thorough physical examination assessing for signs of hormone excess: blood pressure measurement (hypertension), BMI and central obesity, striae, skin changes, acanthosis nigricans, peripheral edema, signs of virilization (hirsutism, clitoromegaly), or precocious puberty
Palpation of the abdomen for masses.
Investigations:
Initial investigations focus on biochemical screening for hormone hypersecretion and imaging for characterization
Laboratory tests include: 24-hour urinary catecholamines and metanephrines (for pheochromocytoma), overnight low-dose dexamethasone suppression test (LDDST) for cortisol (for Cushing's syndrome), plasma aldosterone concentration (PAC) and plasma renin activity (PRA) with calculation of aldosterone-to-renin ratio (ARR) for hyperaldosteronism, and serum electrolytes (especially potassium)
Imaging: CT scan is the primary modality for adrenal lesion characterization, assessing size, attenuation (Hounsfield units - HU), presence of necrosis, calcification, and enhancement patterns
Lipid-rich lesions (<10 HU) are usually benign adenomas
Lesions >20 HU are more suspicious for non-adenoma, potentially malignancy
MRI can be useful for assessing soft tissue detail, especially if CT is equivocal or in pregnant patients.
Differential Diagnosis:
Adrenal adenoma (functional or non-functional), adrenal carcinoma, pheochromocytoma, myelolipoma, adrenal cyst, metastatic disease to the adrenal gland, adrenal hemorrhage, adrenal lymphangioma.
Imaging Assessment
Ct Scan Interpretation:
CT scan is crucial
Key parameters to evaluate include size (>4 cm is concerning for malignancy), attenuation (lesions with <10 HU on contrast-enhanced CT are typically benign adenomas
>20 HU suggests other etiologies like carcinoma or pheochromocytoma), presence of necrosis, calcifications, and enhancement patterns post-contrast
Features suggestive of malignancy include irregular margins, heterogeneous enhancement, and central necrosis.
Mri Role:
MRI is complementary to CT, particularly useful for better soft-tissue characterization, differentiating benign from malignant lesions, and assessing tumor invasion
Specific sequences like T2-weighted imaging can help
Chemical shift imaging can aid in identifying lipid-rich adenomas.
Size And Growth Criteria:
Lesions measuring >4 cm are generally considered at higher risk for malignancy and require more aggressive evaluation
Follow-up imaging is essential for masses <4 cm to assess for growth, which can also indicate malignancy or functional changes.
Hormonal Evaluation
Screening Protocols:
Standard biochemical screening for functional tumors includes: overnight 1mg LDDST for subclinical Cushing's syndrome, 24-hour urinary fractionated metanephrines and normetanephrines for pheochromocytoma, and PAC/PRA for primary hyperaldosteronism
Serum potassium and sodium levels are also important
Additional tests may be guided by imaging findings or clinical suspicion.
Biochemical Cutoffs:
For LDDST, a morning serum cortisol level <1.8 mcg/dL (50 nmol/L) generally excludes Cushing's syndrome
For pheochromocytoma, elevated urinary metanephrines/normetanephrines are diagnostic
For hyperaldosteronism, a PAC > 10 ng/dL and an ARR > 20-30 are suggestive, requiring further confirmatory testing.
Hormonal Implications:
Detecting hormonal hypersecretion is critical
Uncontrolled cortisol excess leads to Cushing's syndrome, impacting growth and metabolism
Uncontrolled aldosterone excess causes hypertension and hypokalemia
Pheochromocytomas can cause life-threatening hypertensive crises.
Management Strategy
Benign Adenomas Monitoring:
Small (<4 cm), homogeneous, lipid-rich (<10 HU) incidentalomas without biochemical evidence of hormone excess are typically managed with active surveillance
This involves periodic reassessment of size by imaging and biochemical evaluation for hormone hypersecretion, usually annually for the first 1-2 years, then less frequently if stable.
Functional Tumors:
Functional tumors require specific treatment: Cushing's syndrome may be managed medically (e.g., ketoconazole, metyrapone) or surgically
Primary hyperaldosteronism is managed with mineralocorticoid receptor antagonists (e.g., spironolactone, eplerenone) or surgery
Pheochromocytomas require surgical resection, preceded by alpha-adrenergic blockade (e.g., phenoxybenzamine) and then beta-adrenergic blockade.
Adrenal Carcinoma Evaluation:
Larger (>4 cm), heterogeneous, or biochemically active lesions, or those with suspicious imaging features, warrant further investigation for adrenal carcinoma
This may involve biopsy (though often avoided due to seeding risk), or surgical resection based on clinical suspicion and patient factors.
Key Points
Exam Focus:
Differentiation between benign adenomas and potentially malignant/functional tumors
Appropriate biochemical screening tests and interpretation of their results
Imaging features that raise suspicion for malignancy
Management algorithms for incidentalomas based on size, imaging, and biochemistry.
Clinical Pearls:
Always consider the patient's age and potential for pubertal changes
A solitary nodule <1 cm is usually benign, but any incidental finding warrants a systematic approach
Remember that adrenal incidentalomas can be bilateral.
Common Mistakes:
Over-reliance on imaging alone without biochemical screening
Inadequate follow-up protocols for stable incidentalomas
Delayed surgical management of confirmed functional tumors or suspected malignancies
Failure to consider pheochromocytoma in the differential diagnosis of hypertension.