Makindo Medical Notes.com

Related Subjects: |Adrenal Physiology |Addisons Disease |Phaeochromocytoma |Adrenal Adenomas |Adrenal Cancer |Cushing Syndrome |Cushing Disease |Congenital Adrenal hyperplasia |Primary hyperaldosteronism (Conn's syndrome) |ACTH |McCune Albright syndrome

Adrenal adenomas are the most common benign adrenal neoplasm, found in up to 5% of patients on CT

About

• Cortisol or Aldosterone or Sex hormone producing adenomas may be bilateral or occur simultaneously
• Small, asymptomatic adrenal nodule most likely to represent adrenal adenoma

Aetiology

• Adrenal adenomas have been linked to mutations or activation of the cAMP-dependent pathway, including ACTH-receptor (MC2R gene), PRKAR1A and PDE11A.

Clinical

• Asymptomatic or may cause Cushing's Syndrome
• Hypertension due to Primary hyperaldosteronism
• Rarely, virilization or feminization.

Investigations

• Urinary free cortisol testing. Exclude other causes of Cushing syndrome
• CT Abdomen: Adrenal adenomas are typically small, less than 3 cm in size, and of homogenous attenuation on CT. Consider comparison with any available prior imaging to establish stability over 12-month period and avoid unnecessary additional testing. CT/MR can confirm Lipid-rich adenomas which lowers the attenuation of the lesion. An adrenal lesion with Hounsfield units of less than 10 on unenhanced CT is a benign, lipid-rich, adrenal adenoma. Adrenal nodules without characteristic CT or MR findings of benign adenomas may be adrenal malignancy or lipid-poor adenomas. Adrenal nodules that are indeterminate on CT and demonstrate FDG avidity greater than that for the liver are often suspicious for adrenal malignancy.
• Adrenal vein sampling if high cortisol and low ACTH.
• FDG PET the vast majority of adenomas demonstrate background FDG avidity. An FDG-avid adrenal mass is suspicious for malignancy until proven otherwise.

Pathology

• Adenomas are rarely larger than 50 g or 5 cm in diameter
• Adenomas causing Primary hyperaldosteronism are commonly smaller than usual, often no larger than 2 cm in diameter, and appear orange-yellow or yellow; they may be multiple or even bilateral. In patients with primary hyperaldosteronism who are treated with spironolactone, spironolactone bodies may be found in the neoplastic cells as well as in the adjacent non-neoplastic zona glomerulosa. These bodies appear as intracytoplasmic eosinophilic globules, 2 to 15 µm, often surrounded by clear spaces. Electron microscopic studies have shown spironolactone bodies to be composed of lamellar whorls of membranes thought to be derived from smooth endoplasmic reticulum
• Glucocorticoid-secreting neoplasms are comparatively larger, with a bright yellow or orange cut surface secondary to the presence of abundant lipid
• A subset of adrenocortical adenomas is diffusely pigmented; these tumours are also referred to as black adenomas. Black adrenocortical adenomas are usually clinically functional and associated with Cushing's syndrome

Differentials

• Adrenal pseudocyst
• Phaeochromocytoma
• Adrenocortical carcinoma

Management

• Referral to Oncology MDT for assessment and planning and risk assessing
• Spironolactone for Aldosterone secreting adenomas or hyperplasia
• Adrenalectomy: ‘cures’ adenomas but not cancers.
• Radiotherapy & adrenolytic drugs (mitotane) follow if carcinoma.

References

• Colection of articles