Adrenal Incidentaloma
An adrenal incidentaloma is an adrenal mass found by chance on imaging — and every one must be triaged with exactly two questions: is it functioning (hormones) and is it malignant (imaging phenotype + size).
The big picture
Cross-sectional imaging frequently finds adrenal masses. Most are benign non-functioning adenomas, but a minority are hormonally active (cortisol, aldosterone, catecholamines) or malignant (adrenocortical carcinoma or metastasis). The job is to sort each mass along those two axes.
Every incidentaloma gets two questions — functioning? (hormones) and malignant? (imaging + size) — and you exclude phaeochromocytoma before any biopsy.
Red flags
Phaeochromocytoma — metanephrines; alpha-blockade before any surgery; never biopsy first.
Suspicious for adrenocortical carcinoma — surgical referral, avoid biopsy.
Consider metastasis — but exclude phaeochromocytoma before biopsy.
Symptom sorter
Screen the hormones in every case.
Diagnostic algorithm
Each step answers one question. Tap to expand.
Treatment ladder
Treat based on the two questions: remove functioning tumours and those suspicious for malignancy; surveil benign non-functioning small masses.
Complications
- Missed phaeochromocytoma (crisis)
- Missed cortisol/aldosterone excess (cardiometabolic harm)
- Missed adrenocortical carcinoma
- Unnecessary adrenalectomy for benign adenomas
- Biopsy-precipitated phaeochromocytoma crisis
- Apply the two questions to every mass
- Never biopsy before excluding phaeochromocytoma
- Refer functioning/suspicious masses for surgery; surveil benign ones
Summary tables
The two-question framework
| Question | Tests | If positive |
|---|---|---|
| Functioning? | DST, metanephrines, ARR, androgens | Treat/operate for the hormone |
| Malignant? | HU, washout, size, growth | Adrenalectomy (en bloc if ACC) |
| Both negative, small | — | Surveillance |
Memory hooks
Two questions: functioning? malignant?
Screen everyone: DST + metanephrines (± ARR).
Benign adenoma = low HU + good washout.
Big, lipid-poor, growing = think cancer.
Never biopsy before metanephrines.
Board traps
Adrenal mass biopsied → hypertensive crisis (it was a phaeo).
Non-functioning 5 cm lipid-poor mass observed instead of resected.
Resistant hypertension + hypokalaemia ignored (missed aldosteronoma).
Clinical cases
A 55-year-old has a 2.5 cm adrenal mass found on a CT for back pain. It measures 6 HU unenhanced with good washout. BP is normal.
What work-up is required and what is the likely outcome?