Discordance Between Imaging and Immunohistochemistry in Primary Aldosteronism

Presentation Number: SUN 508
Date of Presentation: April 2nd, 2017

Aya T. Nanba*1, Richard J. Auchus1, Kazutaka Nanba1, J. Brian Byrd2, James J. Shields1, Thomas J Giordano1, Barbra S. Miller1, William E. Rainey3 and Adina F. Turcu3
1University of Michigan, Ann Arbor, MI, 2Univ of Michigan, Ann Arbor, MI, 3The University of Michigan, Ann Arbor, MI

Abstract

Background:Primary aldosteronism (PA) is most commonly attributed to an aldosterone producing adenoma (APA) or to idiopathic hyperaldosteronism/bilateral adrenal hyperplasia (IHA/BAH). Correct subtyping is essential when surgery is considered. Adrenal vein sampling (AVS) and/or computed tomography (CT) are used for PA subclassification. However, clinical and/or biochemical improvement is not achieved in all patients with presumed APA.

Objective:To investigate the PA cases with poor clinical and/or hormonal benefit after surgical treatment.

Methods:We studied 170 patients who underwent AVS for PA subclassification at the University of Michigan, between 2009 and 2016. We reviewed their clinical, biochemical, imaging, AVS and pathology results. Bilateral AVS was performed simultaneously and samples were obtained before and after cosyntropin stimulation. The daily defined doses of antihypertensive medications were calculated using the WHO ATC/DDD Index (MedI). Postsurgical outcome was ascertained as “not improved” if the following hormonal and clinical criteria were met: serum aldosterone did not decrease by at least 50%, renin remained < 1 ng/ml/h, and the MedI did not decrease by at least 0.5 after surgery. We performed immunohistochemistry (IHC) for aldosterone synthase (CYP11B2) and 17α-hydroxylase (CYP17A1) of the removed adrenal tissue in patients without improvement after adrenalectomy.

Results:Bilateral catheterization was successful in 159 (94%) patients and 87 (55%) were deemed to have unilateral PA. In total, 55 patients (37 men, median age 54 years) underwent adrenalectomy. Of these, 9 (16%) patients showed incomplete hormonal normalization or no clinical improvement, and 3 (5.5%) patients had no hormonal or clinical benefit. On CT, 2 of the latter patients had a single adrenal nodule, and AVS suggested lateralization to the same side in both. The third patient had mild diffuse adrenal nodularity with a dominant nodule on both sides, and AVS indicated lateralization to the adrenal with the largest nodule. All three patients underwent partial adrenalectomy. Clinical pathology was consistent with an adrenocortical adenoma in all. Paraffin-embedded tissue was available in two of these cases, and both demonstrated a nodule that was negative for CYP11B2 and positive for CYP17A1 IHC. Hypercortisolism was excluded in 2 of the patients and not tested in the third.

Conclusion: Dominant adrenal nodules, despite lateralized AVS, are not always the source of aldosterone in PA. These data caution against partial adrenalectomy and reliance on CT findings for patients with PA.

 

Nothing to Disclose: ATN, RJA, KN, JBB, JJS, TJG, BSM, WER, AFT