Fact-sheet: Adrenocortical adenoma


Updated on 09/25/2025 at 1:49 PM

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Definition

Benign cortical lesion of the Adrenal gland.

High frequency (up to 10% of autopsy series).

Raises the issue of incidentalomas given the increasing number of CT examinations performed.

Clinical features

Either non-hyperfunctioning or secreting:

  • Nonsecreting adenomas: 70%
  • Cortisol-secreting adenoma (mildly secreting or subclinical): 8%
  • Conn's adenoma: 1%

Cortisol hypersecretion = Cushing syndrome

  • Resistant hypertension, obesity with "moon" face, skin and hair changes, osteoporosis, mood disorders.

Aldosterone hypersecretion = Primary hyperaldosteronism

  • Resistant hypertension, signs of hypokalemia (tetany, muscle pain, polyuria, polydipsia)

Secretion deficit = Adrenal insufficiency

  • General deterioration, digestive disorders, melanoderma

Laboratory findings

Detection of Cushing Syndrome

  • Screening with dynamic dexamethasone suppression test: negative in Cushing syndrome
  • Confirmation by measurement of serum cortisol (diurnal cycle) and 24-hour urinary free cortisol

Detection of primary hyperaldosteronism

  • Hypokalemia (9-37% of cases)
  • Hyperaldosteronemia: >18 ng/dL or >0.5 nmol/L
  • Elevated aldosterone/renin ratio: >34 ng/dL or >0.95 nmol/L
  • Confirmation by fludrocortisone suppression test or saline infusion test

Detection of adrenal insufficiency

  • Screening with standard Synacthen (ACTH) stimulation test
  • Confirmation by measurement of ACTH, cortisol, and aldosterone

Ultrasound

Homogeneous adrenal mass.

CT

Round, homogeneous, well-defined lesion, less than 4 cm with unenhanced attenuation <20 HU, or less than 6 cm with attenuation <10 HU, in the absence of a neoplastic context.

Intracellular fat:

  • Absolute washout [(portal HU - 15-min HU) / (portal HU - unenhanced HU)] > 60%
  • Relative washout [(portal HU - delayed HU) / portal HU] > 40%

New recommendations from the European Society of Radiology

Recommendations for true incidentalomas: - in the absence of a neoplastic context, - and in the absence of suspected adrenal pathology. According to: Seow JH, Stella DL, Welman CJ, Somasundaram AJ, Gerstenmaier JF. Washed up: the end of an era for adrenal incidentaloma CT. Insights Imaging. 2025 Jun 27;16(1):136. doi: 10.1186/s13244-025-02015-4. PMID: 40579670; PMCID: PMC12204974.Unenhanced CT AttenuationSize1-4 cm4-6 cm> 6cm< 10 HUBenign No follow-up10-20 HUProbably benign Unenhanced follow-up at 6-12 months20-40 HUProbably benign Unenhanced follow-up at 6-12 monthsMultidisciplinary team meeting and/or surgical opinion>40 HUCaution Individualized follow-up

MRI

Detection of intracellular fat by signal drop on opposed-phase imaging > 30%: [(IP Signal - OP Signal) / IP Signal] > 30%

Nuclear medicine

No uptake on MIBG scintigraphy (pheochromocytoma) or on PET-CT (adrenocortical carcinoma, metastases)

Management

No follow-up if typical criteria are met.
Endocrinology consultation for biological workup (even in the absence of clinical signs: 10% of subclinical secretions)

Differential diagnosis

  • Adrenocortical hyperplasia: Mean thickness of the adrenal limbs > 5mm in a context of primary hyperaldosteronism = bilateral adrenal hyperplasia. Unilateral or bilateral enlargement of the adrenal body >10 mm. Smooth or nodular
  • Adrenal hematoma: clinical context, initial hyperdensity, cystic involution +/- calcifications, stability
  • Myelolipoma: fat density < -30 HU
  • Pheochromocytoma: central necrosis, MIBG scintigraphy, biological workup
  • Adrenocortical carcinoma: heterogeneous arterial hypervascularization of the solid component. Tuberculosis: bilateral involvement, calcifications
  • Metastases to adrenal gland: PET-CT