A 35-year-old woman with hypertension, hypokalaemia, and elevated plasma aldosterone-to-renin ratio undergoes adrenal CT showing a 1.5 cm right adrenal adenoma. Pathology of the resected adenoma shows pale, lipid-laden 'clear cells' with abundant cytoplasm and small nuclei. Which zone of the adrenal cortex does this adenoma recapitulate?
- A Zona glomerulosa (mineralocorticoid-secreting zone) ✓
- B Zona fasciculata (glucocorticoid-secreting zone)
- C Zona reticularis (androgen-secreting zone)
- D Adrenal medulla (catecholamine-secreting chromaffin cells)
Explanation
Conn's syndrome (primary hyperaldosteronism) is caused by an aldosterone-secreting adenoma originating from the zona glomerulosa, the outermost layer of the adrenal cortex. The adenoma recapitulates zona glomerulosa histology — cells with pale, lipid-laden cytoplasm ('clear cells') reflecting cholesterol-rich steroidogenic activity. Importantly, adrenal cortical adenomas causing Conn's syndrome also frequently contain hybrid cells resembling zona fasciculata ('zona fasciculata-like cells'), explaining the pale, mixed appearance. KCNJ5 or ATP1A1 somatic mutations are found in the majority of aldosterone-producing adenomas.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.