Adrenal hyperplasia

Adrenal hyperplasia refers to non-malignant growth (enlargement) of the adrenal glands and is a rare cause of ACTH-independent Cushing syndrome, with unilateral adrenal cortical adenomas being the commonest. Approximately 20% of Conn syndrome cases are secondary to adrenal hyperplasia. In diffuse hyperplasia, the limbs of the adrenal glands are >5 cm in length and >10 mm in thickness. It may be unilateral in some situations ⁶.

Pathology

Classification

Adrenal hyperplasia can be classified according to:

• inheritance
  • congenital
    • congenital adrenal hyperplasia (CAH)
    • primary pigmented nodular adrenal dysplasia
  • acquired adrenal hyperplasia
• morphology
  • micronodular adrenal hyperplasia
  • macronodular adrenal hyperplasia
    • adrenocorticotropin independent macronodular adrenocortical hyperplasia (AIMAH) 

Radiographic features

• enlarged limbs of one or both adrenal glands >10 mm thick
• normal adrenal morphology maintained
• nodular or uniform

MRI

• high lipid content and thus may demonstrate signal dropout on out-of-phase chemical shift imaging
• signal dropout due to lipid content overlaps with adrenal cortical adenomas

See also

• bilateral adrenal enlargement