Adrenal Gland Cysts: Overview, Effects, and Management

What Are Adrenal Cysts?

Types of Adrenal Cysts (Histologic Classification)

Effects and Clinical Consequences

1. Mass Effect (Large Cysts)

• Large cysts (especially >10 cm) can cause abdominal/flank pain, discomfort, and a palpable flank mass by displacing adjacent organs (kidney, pancreas, spleen, liver).
• Distinguishing a large adrenal cyst from lesions of neighboring organs can be difficult clinically.

2. Mostly Asymptomatic (Small Cysts)

• The majority (~90%) of adrenal cysts are asymptomatic and discovered incidentally on imaging done for unrelated reasons.

3. Hormonal (Functional) Effects

• While most adrenal cysts are non-functional, endocrinologic evaluation is always recommended to exclude active lesions (e.g., cortisol or aldosterone excess, or pheochromocytoma).
• Cysts can occasionally arise in the setting of a functioning adrenal neoplasm undergoing cystic degeneration.

4. Risk of Hemorrhage

• Cysts - particularly pseudocysts - can hemorrhage spontaneously, leading to acute abdominal pain, hemodynamic instability, or even acute abdomen.
• On CT, higher fluid density (>30 HU) within the cyst suggests hemorrhage or intracystic debris.

5. Malignancy Risk

• Approximately 7% of adrenal cysts are associated with underlying malignancy, almost entirely within the pseudocyst subtype.
• Cystic neoplasms masquerading as simple cysts include adrenocortical carcinoma (ACC), pheochromocytoma, and adenoma.
• Cystic neoplasms tend to be larger (>7 cm) and have thicker walls than true benign cysts.
• Because histology in most series comes from surgical specimens, the 7% malignancy rate may overestimate the true population risk. (Campbell-Walsh Wein Urology, p. 3167)

6. Cyst Growth and Recurrence

• In small series, ~60% of adrenal cysts increased in size over follow-up, and only 25% decreased. About one-third of patients experience ongoing enlargement.

7. Calcification

• Peripheral calcifications are seen in 15-70% of adrenal cysts on imaging. These are typically rim-like but occasionally nodular.

8. Infection / Rupture

• Infection of the cyst contents and spontaneous rupture, though rare, represent potential complications - especially in larger lesions.

Imaging Features

• CT (study of choice): Thin non-enhancing wall, fluid-density content (near water attenuation). Thickened walls, solid components, or septations raise suspicion for necrotic mass or cystic neoplasm.
• MRI: Simple cysts appear hypointense on T1 and hyperintense on T2.
• Radiology alone cannot exclude malignancy; aspiration or surgical excision is often needed when doubt exists. (Grainger & Allison's Diagnostic Radiology)

Management

Indications for Surgery

1. Symptomatic (pain, mass effect)
2. Functional (hormonally active)
3. Size >5 cm (risk of hemorrhage and secondary complications)
4. Radiologic suspicion of malignancy (thick walls, solid components, local invasion)

Conservative Management

• Small (<4 cm), asymptomatic, thin-walled, non-functional cysts with benign radiographic features can be observed without follow-up imaging, per the European Society of Endocrinology guidelines.
• If follow-up is chosen (e.g., borderline size), repeat CT or MRI at 6-12 months is recommended.

Aspiration

• Aspiration can be both diagnostic and therapeutic in select cases.
• Must be performed only after pheochromocytoma is biochemically excluded (aspiration can precipitate a hypertensive crisis if the cyst overlies or communicates with a pheo).
• Aspirate should be sent for cytology, Gram stain, cortisol, triglycerides, and amylase (for left-sided cysts).

Prognosis

• Benign cysts: Excellent prognosis after resection; follow-up is needed to watch for reaccumulation.
• Cysts with malignancy: Follow-up is governed by the underlying malignant histology (e.g., ACC protocols).

Clinical Scenario Summary

• Adrenal cyst: 1.2 x 0.8 cm (small, <2 cm)
• Malignant (accelerated) hypertension
• Elevated serum aldosterone
• Elevated urinary cortisol
• Likely: Co-secreting functional adrenal lesion - both Conn's syndrome (primary hyperaldosteronism) AND subclinical/overt Cushing's syndrome from the same small adrenal cyst/adenoma

Management Plan

STEP 1 - Immediate: Treat the Malignant Hypertension

• Admit to ICU/HDU immediately
• IV antihypertensives - reduce MAP by no more than 25% in the first hour:
  • IV labetalol (first choice if no contraindication)
  • IV nicardipine (calcium channel blocker)
  • IV hydralazine or sodium nitroprusside as alternatives
• Avoid ACE inhibitors/ARBs initially until renal function is established
• Target: Bring BP down gradually - do NOT normalize acutely (risk of cerebral hypoperfusion)
• Begin spironolactone (aldosterone antagonist, 25-50 mg/day) orally once oral medications tolerated - this addresses the root cause of hyperaldosteronism-driven hypertension directly
• Correct hypokalemia (common with hyperaldosteronism - monitor K+ closely)

STEP 2 - Confirmatory Biochemical Workup

For Hyperaldosteronism:

For Hypercortisolism:

Exclude Pheochromocytoma (MANDATORY before any intervention):

• Plasma free metanephrines OR 24-hr urinary metanephrines/catecholamines
• Must be done BEFORE any aspiration or surgery - failure to do so risks fatal hypertensive crisis

STEP 3 - Imaging Evaluation

• CT abdomen without contrast (non-enhanced CT):
  • Hounsfield units (HU) <10 = lipid-rich adenoma (benign)
  • HU >10 = indeterminate, needs washout study or MRI
  • Size <2 cm with benign features + functional = still warrants surgery given dual hormone excess
• MRI adrenals if CT indeterminate (chemical shift imaging to detect intracellular lipid)
• Adrenal Vein Sampling (AVS) - considered if:
  • Bilateral lesions suspected
  • Age >40 (non-functioning incidental adenomas common, may confuse lateralization)
  • CT inconclusive for lateralization
  • AVS has sensitivity 95%, specificity 100% for lateralized aldosterone secretion (Campbell-Walsh Wein Urology, p. 3167)

STEP 4 - Definitive Treatment

Surgical (Recommended - this lesion is functional with dual hormone secretion):

• Laparoscopic adrenalectomy - preferred approach for lesions ≤2 cm, minimally invasive
• Robotic-assisted approach is an acceptable alternative

Preoperative Preparation (Critical):

1. Spironolactone (25-100 mg/day) for 4-6 weeks preoperatively - corrects hypokalemia and volume overload
2. Correct hypokalemia to >3.5 mEq/L before surgery
3. BP control - target <140/90 mmHg with spironolactone + additional agents as needed
4. Steroid coverage mandatory - because urinary cortisol is elevated, the contralateral adrenal gland will be suppressed:
   • Give hydrocortisone 100 mg IV at induction, then 50 mg IV q8h for 24 hours, then taper
   • Continue until morning cortisol confirms recovery of contralateral adrenal (may take weeks-months)
5. Cardiopulmonary and anesthetic review preoperatively (Cushing's risk: airway, DVT, aspiration)
6. Prophylactic anticoagulation (hypercortisolism = VTE risk)
7. Proton pump inhibitor preoperatively

If Surgery Deferred or Patient Unfit:

• Spironolactone 25-100 mg/day (or eplerenone if spironolactone intolerance - less anti-androgenic side effects)
• Add standard antihypertensives (calcium channel blocker, thiazide)
• Regular monitoring of electrolytes, BP, cortisol levels

STEP 5 - Postoperative Monitoring

Key Points Summary

Clinical note: This management plan is a guide based on standard principles. Final decisions require a multidisciplinary team - endocrinologist, endocrine surgeon, radiologist, and anesthesiologist - with individualized assessment of the patient's full clinical picture.

Surgical Choice: Total Adrenalectomy vs. Partial vs. Cystectomy

The Three Options Compared

For THIS Patient (1.2 x 0.8 cm, dual hormone secretion - aldosterone + cortisol)

Simple Cystectomy Alone - NOT appropriate

• Simple enucleation/cystectomy is reserved for non-functional, benign, simple cysts
• This patient has a co-secreting functional lesion (elevated aldosterone + urinary cortisol)
• The hormonal excess does not come from the cyst wall alone - it comes from the underlying adrenal cortical tissue pathology (adenoma undergoing cystic change, or functional cyst)
• Cystectomy alone would leave behind the functioning tissue and fail to cure hypertension or normalize hormones

Partial Adrenalectomy (Cortical-Sparing) - PREFERRED for this patient

1. Small tumor (1.2 x 0.8 cm, <2 cm) - ideal candidate for tissue-sparing surgery. Per PMC/NIH evidence, partial adrenalectomy is strongly supported as first-line for small adrenal tumors
2. Cortisol is already elevated - this means the contralateral adrenal is already partially suppressed. Total adrenalectomy would guarantee adrenal insufficiency requiring lifelong steroid replacement
3. Conn's adenoma (aldosterone) specifically - the 2026 meta-analysis by Kashi et al. (PMID 41618588) found:
   • Partial adrenalectomy was NOT associated with higher recurrence in Conn's adenoma patients (unlike pheochromocytoma)
   • Partial adrenalectomy had significantly fewer perioperative complications in Conn's patients
   • Partial adrenalectomy cut the risk of adrenal insufficiency by 51% (RR 0.49) and steroid dependence by 56% (RR 0.44)
4. Bilateral cysts occur in 8-10% of adrenal cyst cases - preserving cortex on the operated side is prudent
5. Sabiston Surgery confirms: "When possible, a cortical-sparing or partial adrenalectomy should be performed to avoid permanent adrenal insufficiency" (Sabiston Textbook of Surgery)

• Remove the cyst/tumor with a thin (2-3 mm) rim of normal adrenal cortex
• Leave remaining healthy adrenal cortex in situ
• Done laparoscopically (transperitoneal or retroperitoneoscopic) given size ≤2 cm
• Robotic approach acceptable at high-volume centers

Total (Unilateral) Adrenalectomy - Reserved for specific situations

Decision Summary for This Case

Functional small cyst (1.2 x 0.8 cm)
        ↓
Pheochromocytoma excluded? → YES (mandatory before proceeding)
        ↓
Imaging benign? (no invasion, thin wall, <2 cm) → YES
        ↓
        ▶ PARTIAL (cortical-sparing) ADRENALECTOMY
          - Laparoscopic approach
          - Remove cyst + thin rim of normal cortex
          - Preserve remaining adrenal tissue
          - Perioperative steroid cover (cortisol already elevated)
          - Monitor K+ postop for rebound hyperkalemia

Key Evidence

• Kashi et al. 2026 - Meta-Analysis (PMID 41618588): 19 studies, 3,165 patients - partial adrenalectomy reduces adrenal insufficiency risk by 51%, no higher recurrence in Conn's adenoma, fewer complications
• PMC/NIH review: "Partial adrenalectomy is strongly supported as first-line for small (<5 cm) functional adrenal tumors"
• Schwartz's Surgery: "Cortical-sparing subtotal adrenalectomy may preserve adrenocortical function and avoid the morbidity of bilateral total adrenalectomy"
• Campbell-Walsh Wein Urology: "Partial adrenalectomy: underused first-line therapy for small adrenal tumors"

Revised Scenario: Pure Primary Hyperaldosteronism (Conn's Syndrome)

Pathophysiology Recap

• Na+ retention → ECF expansion → ↑cardiac output → Malignant hypertension
• K+ wasting → Hypokalemia → weakness, arrhythmia, tetany
• H+ secretion → Metabolic alkalosis
• Renin suppressed (high ECF pressure inhibits renin release) - hallmark of primary aldosteronism
• Long-term: LV hypertrophy, stroke, MI, renal damage (Robbins Pathology; Costanzo Physiology)

MANAGEMENT APPROACH

Phase 1 - Immediate (Malignant HTN Emergency)

Phase 2 - Confirmation and Localization

Phase 3 - Preoperative Medical Optimization (4-6 weeks)

Phase 4 - Definitive Surgery

• Lesion is small (1.2 x 0.8 cm), unilateral, benign in appearance
• No steroid cover required (cortisol normal, contralateral adrenal is fully functional)
• Short hospital stay, quick recovery

• Monitor serum K+ daily - rebound hyperkalemia can occur up to 1 month post-op (as contralateral suppressed aldosterone zone recovers, K+ can spike)
• Stop spironolactone postoperatively
• Check BP at each visit - residual hypertension (from vascular remodeling) may persist for months; treat with standard antihypertensives if needed
• Confirm cure: recheck aldosterone + renin at 1-3 months

MEDICATIONS: Adverse Effects and How to Control Them

1. SPIRONOLACTONE (First-line MRA)

2. EPLERENONE (Second-line MRA - preferred if spironolactone intolerance)

3. FINERENONE (Newest non-steroidal MRA)

• Non-steroidal - no progesterone or androgen cross-reactivity
• Additional anti-fibrotic, anti-inflammatory, anti-remodeling properties in kidney, heart, vasculature
• Distributes more evenly between heart and kidneys vs. steroidal MRAs
• Approved for hypertension and heart failure
• Reduce starting dose from 20 mg to 10 mg if CrCl ≤60 mL/min; contraindicated CrCl ≤25 mL/min
• Avoid strong CYP3A4 inhibitors
• Main AE: hyperkalemia

Drug Choice Decision Tree

Primary aldosteronism (pure - normal cortisol)
          ↓
Surgical candidate? → YES → Spironolactone 50-100 mg/d for 4-6 weeks preop
                              ↓ surgery (partial adrenalectomy)
                              ↓ STOP spironolactone postop
                              ↓ Monitor K+, BP, aldosterone

NOT surgical / awaiting / declines surgery?
          ↓
Male patient with concern for sexual side effects → Eplerenone 50-100 mg BD
Female patient → Spironolactone 25-100 mg/d (first choice)
Renal impairment (CrCl 25-60) → Finerenone 10 mg/d (reduced dose)
CrCl <25 → MRAs contraindicated; use amiloride (K+-sparing) + antihypertensives

Summary Table

Consequences After Adrenalectomy (Partial vs. Total)

Context: Pure Primary Hyperaldosteronism, 1.2 x 0.8 cm, Normal Cortisol

A. INTRAOPERATIVE COMPLICATIONS

B. EARLY POSTOPERATIVE CONSEQUENCES (Days to Weeks)

1. Rebound Hyperkalemia ⭐ (Most Important for THIS patient)

• Mechanism: Aldosterone was driving K+ excretion; when removed suddenly, K+ reabsorbs and serum K+ rises sharply
• Timeline: Can occur within days, persists up to 1 month post-op
• Risk: Cardiac arrhythmia - especially dangerous given the pre-existing malignant hypertension and LV strain
• Management: Daily K+ monitoring; withhold K+ supplementation immediately post-op; avoid spironolactone/eplerenone post-op; if severe, calcium gluconate IV + insulin/dextrose + Kayexalate

2. Hypotension

• Mechanism: Sudden loss of aldosterone → Na+/water loss → volume contraction
• Management: IV fluids, fludrocortisone rarely needed if cortisol is normal (which it is in this patient)

3. Wound Infection

• Rate ~1.5%
• Standard postoperative wound care and monitoring

4. Cardiac Complications

• Rate ~0.8%
• Pre-existing malignant HTN with LV hypertrophy increases cardiac risk
• ICU monitoring for 24-48 hrs post-op

5. Pulmonary Complications

• Rate ~0.6%
• Atelectasis, pneumonia (especially if retroperitoneoscopic approach used)

C. HORMONAL CONSEQUENCES (Differs Between Partial and Total)

PARTIAL Adrenalectomy

TOTAL Adrenalectomy (Unilateral)

Key difference: In THIS patient with normal cortisol, the contralateral adrenal is NOT suppressed, so risk of permanent adrenal insufficiency after unilateral total adrenalectomy is very low. Still requires short monitoring post-op.

D. FUNCTIONAL / BIOCHEMICAL OUTCOMES (The "Success" Consequences)

Hypertension Outcomes Specifically:

• ~59% complete cure (normotensive off all medications)
• ~26% improved control (reduced drug requirements)
• ~15% persistent hypertension requiring medications
• Duration of BP resolution: 1-18 months post-op (mean ~5-6 months)
• Residual hypertension is due to established vascular remodeling and nephrosclerosis from years of aldosterone-driven damage - not surgical failure

• Long duration of HTN before surgery (as in this malignant HTN case - a risk factor)
• Older age
• Renal impairment
• Higher serum aldosterone pre-op
• Obesity

E. LONG-TERM CONSEQUENCES

F. COMPARISON SUMMARY TABLE

G. MONITORING PROTOCOL POST-SURGERY