Primary Aldosteronism due to Unilateral Adrenal Hyperplasia. Report of Two Cases and Review of the Literature.

Abstract

Abstract.Unilateral adrenal hyperplasia (UAH) is a rare, surgically correctable subset of primary aldosteronism(PA), which shows similar endocrine features to aldosterone-producing adenoma (APA). We report here two Japanese patients with UAH. Case 1 was a 62-year-old man with a four-year history of hypertension.Hypokalemia and suppressed plasma renin activity (PRA) with elevated plasma aldosterone concentration (PAC) were observed, while no adrenal nodules were identified by abdominal computed tomographic (CT) scan. Adrenal scintigraphy did not reveal definite localization.The selective adrenal-vein sampling for determinations of PAC showed an overfunctioning left adrenal gland, and a left adrenalectomy was performed.Diffuse micronodular adrenocortical hyperplasia was observed.Case 2 was a 61-year-old man with a six-year history of hypertension. At the first visit to our hospital, hypokalemia and suppressed PRA with elevated PAC were observed.An abdominal CT scan showed a left adrenal mass 1.5 cm in diameter, while adrenal scintigraphy did not reveal definite laterality. A left adrenalectomy was performed, and three macronodules and diffuse micronodular adrenocortical hyperplasia were observed. Hypokalemia, hypertension and endocrine data became normal, and both patients have been well with no signs of recurrence for eight years (case 1) and seven months (case 2) after surgery. Clinical characteristics and endocrine features of UAH are also reviewed.

A Case of Primary Aldosteronism Due to Unilateral Adrenal Hyperplasia

“…There are several reports that bilateral uptake (22) or no uptake (23) or even incorrect side uptake might occur in patients with proven aldosterone producing adenoma (24). For cases of unilateral adrenal hyperplasia, adrenal scintigraphy with or without dexamethasone treatment has been used in 8 cases with varying results: four had a bilateral uptake, 2 had the correct uptake, and 1 had early uptake on the correct side on day 3 followed by bilateral uptake on day 5 ( 6,9,11,13,14,18). In these cases, dexamethasone suppression did not improve the determination of the affected site.…”

Pathological manifestation of difference in washout pattern of adrenal hyperplasia on dynamic CT

“…The stasis of contrast medium may occur on the delayed phase in a tumour mainly composed of clear cells in comparison with a compact cell‐rich tumour. Although the same logic can be applied to AA, previous reports have shown that lipid‐rich AAs do not demonstrate washout patterns different from those of lipid‐poor AAs . However, the authors divided adenomas into lipid‐rich and lipid‐poor groups using non‐enhanced CT attenuation values and did not perform histological analyses of each AA.…”

“…These two diseases can be differentiated from pheochromocytoma, adrenal metastasis and adrenal cancer, which reportedly show low washout rates . AH is composed of clear cells and compact cells and closely resembles AA in histology, although AH is differentiated from AA using several findings such as bilaterality, not encapsulated margin and a transition into the surrounding adrenal cortex as a whole . Not only AA but also AH show variable washout rates, but the difference in washout rates within the same disease has not been fully investigated, and the details are unknown.…”

New concepts in adrenal vein sampling for aldosterone in the diagnosis of primary aldosteronism

“…Nonetheless, differentiating between APA and IHA can be extremely challenging for three reasons: 1) there are rare cases of MUAN, or unilateral autonomous hyperplasia, that can be cured by adrenalectomy [13]; 2) at histopathology the border between a microscopic adenoma and a unilateral hyperplasia or MUAN is undefined; and 3) bilateral APA and APA in the context of BAH can exist [14,15].…”