Is surgery needed for a 3.5 cm adrenal adenoma in an adult with a history of a benign 2.5 cm adrenal adenoma?

Surgery is Indicated for This Growing Adrenal Adenoma

Your patient requires adrenalectomy because the tumor has grown 1 cm over the surveillance period and now measures 3.5 cm, which meets criteria for surgical resection based on both size and growth rate. 1, 2

Critical Decision Points

Growth Rate Analysis

• The 1 cm growth over your surveillance period is concerning and mandates surgical intervention. 1 The NCCN guidelines explicitly state that nonfunctioning tumors showing enlargement >1 cm in 1 year should undergo adrenalectomy for suspected carcinoma. 1
• While benign adenomas can grow, research demonstrates that adenomas grow at a mean rate of 1.0 mm/year (range 0.3-2.8 mm/year), whereas malignant nodules grow at 58.4 mm/year (range 5.8-395.4 mm/year). 3 A growth rate >3 mm/year distinguishes malignancy from adenoma with 100% sensitivity and specificity. 3
• Your patient's growth pattern warrants concern even if the absolute growth rate calculation falls below the malignancy threshold, because the NCCN uses the absolute 1 cm change as the surgical trigger. 1

Size-Based Risk Assessment

• At 3.5 cm, this lesion falls into an intermediate-risk category where malignancy features must be carefully evaluated. 1 The NCCN guidelines note that tumors >3 cm raise suspicion for malignancy, particularly when combined with irregular/inhomogeneous morphology, lipid-poor characteristics, or lack of washout. 1
• The American Urological Association recommends surgical resection for adenomas ≥4 cm due to increased malignancy risk. 2 Your patient at 3.5 cm is approaching this threshold with documented growth.
• Research shows that 48% of patients younger than 60 years with lesions exceeding 4 cm who underwent surgery had appropriate indications, including the one patient with adrenocortical carcinoma in that cohort. 4

Mandatory Pre-Operative Workup

Before proceeding to surgery, you must complete comprehensive hormonal screening:

• 1 mg overnight dexamethasone suppression test to screen for autonomous cortisol secretion (mild autonomous cortisol secretion/MACS). 5, 2, 6
• Plasma or 24-hour urinary metanephrines to exclude pheochromocytoma—this is mandatory before any surgical consideration to prevent fatal cardiovascular events. 2, 6 Never proceed with surgery without excluding pheochromocytoma. 6
• Aldosterone-to-renin ratio if the patient has hypertension and/or hypokalemia. 5, 2, 6
• Androgen screening may be considered given case reports of adenomas co-secreting androgens and cortisol, though this is rare. 7, 8

Imaging Reassessment

• Obtain updated CT imaging with unenhanced sequences to measure Hounsfield units (HU). 5, 2 If HU ≤10, the lesion remains consistent with a lipid-rich adenoma, but this does not change the surgical indication given the documented growth. 5, 2
• If HU >10, perform washout CT or chemical shift MRI to further characterize the lesion and assess for malignancy features. 5, 2
• Evaluate for aggressive features including inhomogeneous appearance, irregular margins, and local invasion, which would suggest suspected carcinoma. 1, 2

Surgical Approach

• Laparoscopic adrenalectomy is preferred when the tumor can be safely resected without capsular rupture. 2, 6 This minimally invasive approach reduces complications and promotes faster recovery. 6
• Plan for possible conversion to open adrenalectomy if intraoperative findings suggest malignancy (irregular margins, heterogeneity, local invasion). 2
• If pheochromocytoma is confirmed, mandatory alpha blockade for 1-3 weeks preoperatively is required. 6

Why Surveillance is Insufficient

• The combination of growth >1 cm and intermediate size (3.5 cm) creates unacceptable risk for missing an early adrenocortical carcinoma. 1, 2 Research demonstrates that antecedent lesions in patients ultimately diagnosed with ACC are often indeterminate by imaging and can be small (25% were <2 cm initially). 9
• Surveillance detected only 50% of ACCs within 24 months, and some lesions showed long-term stability (up to 8 years) before malignant transformation. 9 This unpredictable behavior makes continued observation inappropriate for a growing lesion.
• Current surveillance guidelines are insufficient for diagnosing ACC early enough to impact outcomes. 9

Critical Pitfalls to Avoid

• Never proceed with adrenal biopsy for this workup—it is rarely indicated, carries unnecessary risks, and can trigger hypertensive crisis if unsuspected pheochromocytoma is present. 5, 6
• Do not delay surgery for repeated imaging intervals once the 1 cm growth threshold is met. 1
• Ensure complete hormonal workup is performed even if the mass appears radiologically benign, as approximately 5% of benign-appearing incidentalomas have subclinical hormone production requiring specific perioperative management. 5