Endocrine Abstracts

Introduction & Objectives: A laparoscopic radical adrenalectomy is the standard treatment option for unilateral primary aldosteronism. Partial adrenalectomy for solitary adenomas has been suggested to be feasible and adrenal cortex-sparing. However, solitary adenomas may be rare. The purpose of this study was to assess whether partial adrenalectomy in patients with a seemingly solitary adenoma might be worthwhile by relating perioperative imaging to pathologic findings of excised adrenal glands.

Materials & Methods: Fifteen patients with unilateral primary aldosteronism, based on preoperative CT scan and adrenal vein sampling, were treated by laparoscopic total adrenalectomy. We compared findings of intraoperative EUS, ex-vivo MRI of the adrenal specimen (using a 11.7T MR system), immunohistochemistry (CYP11B2 and CXCR4, a recently described marker for aldosterone producing adenomas) and mutation analysis (KCNJ5, ATP1B2, ATP2B3, CTNNB1) regarding the presence of a solitary adenoma or multinodular hyperplasia.

Results: Considering the final pathology report as the gold standard, sensitivity and specificity to detect multinodular glands with EUS were 41.6% and 33.3%, respectively. Ex-vivo MRI identified thirteen of fifteen adrenals (87%) as multinodular where the pathologist initially classified seven of fifteen (47%) adrenals as multinodular. In the final pathology report, wherein the pathologist combined ex-vivo MRI and histology, the pathologist classified twelve of fifteen (80%) adrenals as multinodular. Immunohistochemistry showed in four of twelve (33%) multinodular glands more than one nodule positive for aldosterone synthase. All nodules positive for aldosterone synthase were also positive for CXCR4. In four of fifteen adrenals (27%) somatic mutations were present. In every gland with a mutation only one nodule harbored this mutation, irrespective of glands with multiple aldosterone synthase positive nodules.

Conclusions: In this study we show that intraoperative endoscopic ultrasound is not sensitive enough to detect multinodular glands. Ex vivo MRI and immunohistochemistry detect adrenal nodules that are frequently missed by routine histopathology. Some of these usually small nodules also produce aldosterone. The results from our study show that multinodular hyperplasia is common and questions suitability of partial adrenalectomy in primary aldosteronism because a solitary adenoma cannot reliably be proven pre- or intraoperatively, not even by EUS.