Endocrine Abstracts

Background: The best lateralization method to ascertain cure after surgery in unilateral primary aldosteronism (PA) is debated. Risk of persistent of PA in those with non-classical adrenal histopathology remains poorly characterized.

Objective: We examined the value of anatomical compared with functional subtyping and the significance of immunohistochemical analysis of CYP11B1 and CYP11B2 for the outcome and histopathological diagnosis of primary aldosteronism.

Design: A retrospective multicenter study of patients operated for PA.

Methods: We identified 277 subjects with a diagnosis of primary hyperaldosteronism (E26.0) who had an adrenalectomy sample available in the Finnish biobanks during 1.1.2000-31.12.2019. Adrenal slides from biobanks were analyzed centrally after CYP11B2 staining and clinical data were obtained from patient registries.

Results: Altogether 179 (64.6%) patients underwent adrenalectomy based on anatomical lateralization on CT or MRI, whereas 43 (15.5%), 14 (5.4%) and 35 (12.6%) were operated based on functional lateralization in adrenal venous sampling (AVS); ¹¹C-metomidate (¹¹C-MTO) -PET or [¹³¹I] norcholesterol scintigraphy, respectively. Adrenalectomy based on functional subtyping more likely resulted in complete or partial clinical cure than anatomical subtyping -based adrenalectomy (88.5 % vs. 72.5 %, P=0.002). Re-evaluation of adrenal samples with CYP11B2 staining revealed aldosterone-producing adenoma (APA) in 146 (67.3 %) subjects and changed the original histopathological diagnosis in 91 (33.2 %) of the subjects. Aldosterone-producing nodules (APN) were more frequently present in those who did not reach clinical cure (22.4 % vs 9.4 %, P=0.012) whereas aldosterone-producing micronodules (APM) were common overall (83.4 %) and did not impact the outcome of adrenalectomy. Frequency of APAs and non-classical features did not differ according to the subtyping method used.

Conclusions: Lateralization detected in functional subtyping can identify unilateral aldosterone production more accurately than anatomical imaging. CYP11B2 staining is elemental for the histopathological diagnosis and complements the postoperative clinical data. Our results suggest the need for prompt long-term follow-up in patients with APNs even after removal of an APA.