Adrenal Incidentalomas

Incidentalomas - Surprise Gland Finds

• Adrenal mass >1 cm diameter, discovered serendipitously on imaging for unrelated conditions.
• Prevalence: Found in ~3-7% of abdominal CT scans; frequency ↑ with age.
• Initial imaging assessment: Non-contrast CT is key.
  • Size: Lesions >4-6 cm raise suspicion for adrenocortical carcinoma (ACC).
  • Attenuation: ≤10 HU (Hounsfield Units) strongly suggests a benign, lipid-rich adenoma.
  • If >10 HU, consider contrast-enhanced CT with washout calculation or MRI.

⭐ The majority (around 70-80%) of adrenal incidentalomas are benign, non-functioning cortical adenomas.

Hormonal Workup - Hormone Havoc

• All patients: Screen for pheochromocytoma & (sub)clinical Cushing's.
• Pheochromocytoma:
  • Plasma free metanephrines OR 24-hr urinary fractionated metanephrines & catecholamines.
  • 📌 Mnemonic: "Pheo Free Met" (Pheochromocytoma = Plasma Free Metanephrines).
• (Sub)clinical Cushing's Syndrome:
  • 1mg overnight dexamethasone suppression test (ODST).
  • Post-DST serum cortisol > 1.8 $µg/dL$ (or >50 $nmol/L$) is positive.
• Primary Aldosteronism:
  • Screen if hypertensive or hypokalemic.
  • Plasma aldosterone concentration (PAC) & plasma renin activity (PRA) for ARR.
  • PAC > 15 $ng/dL$, PRA < 1 $ng/mL/hr$, ARR > 20-30.

⭐ Subclinical Cushing's syndrome is the most common hormonally active tumor found in adrenal incidentalomas.

Management Strategy - Scalpel or Scope?

• Surgery (Laparoscopic Adrenalectomy preferred):
  • All functional tumors (Cushing's, pheochromocytoma, Conn's).
  • Size > 4-6 cm.
  • Radiological suspicion of malignancy (e.g., >10 HU unenhanced CT, poor washout).
  • Significant growth (>1 cm/year) on follow-up.
• Conservative Management (Non-functional, <4cm, benign appearance):
  • Repeat hormonal workup & imaging (CT/MRI) at 6-12 months.
  • Then annually for 1-2 years, then less frequently if stable.
  • Consider surgery if tumor grows significantly or becomes functional.

⭐ Most adrenal incidentalomas (~70%) are benign, non-functioning adenomas; pheochromocytoma must always be ruled out before any intervention, including biopsy.

Key Diagnoses - Nodule Nasties

• Pheochromocytoma:
  • Rule out first! "10% tumor" (bilateral, extra-adrenal, malignant, familial, pediatric).
  • Symptoms: Paroxysmal hypertension, palpitations, headache, sweating (📌 PHE: Palpitations, Headache, Episodic sweating).
  • Biochem: ↑ Plasma metanephrines / 24hr urine metanephrines & VMA.
  • Pre-op: α-blockade (e.g., phenoxybenzamine) then β-blockade.
• Adrenocortical Carcinoma (ACC):
  • Suspect if >4-6 cm, irregular, heterogeneous, calcifications, high attenuation (>10 HU unenhanced CT), poor contrast washout.
  • Often functional (Cushing's, virilization). Surgical resection is key.
• Cushing's Syndrome (Adrenal Adenoma):
  • Autonomous cortisol secretion.
  • Dx: Dexamethasone suppression test (fails to suppress), ↑ 24hr UFC, ↑ late-night salivary cortisol.
• Primary Aldosteronism (Conn's Syndrome):
  • Aldosterone-producing adenoma. Hypertension, hypokalemia.
  • Dx: Aldosterone-Renin Ratio (ARR) >20-30, saline infusion test confirmation.
• Metastasis:
  • Common from lung, breast, kidney, melanoma. Often bilateral; history of primary cancer.

⭐ For pheochromocytoma, always initiate alpha-blockade before beta-blockade to prevent unopposed alpha-adrenergic stimulation leading to a hypertensive crisis.

High‑Yield Points - ⚡ Biggest Takeaways

• Adrenal incidentalomas: Masses >1 cm found serendipitously; most are non-functional benign adenomas.
• Prevalence ↑ with age; initial workup includes CT/MRI and hormonal screening.
• Screen for pheochromocytoma (metanephrines), Cushing's (dexamethasone suppression), and Conn's (aldosterone/renin).
• Surgery for functional tumors, malignancy suspicion (size >4-6 cm, suspicious imaging), or growth.
• Non-functional tumors <4 cm without suspicious features are typically observed with serial imaging.
• Always resect pheochromocytomas after alpha and beta blockade to prevent hypertensive crisis.