Immunohistochemical staining seems mandatory for individualizing and shortening follow-up in unilateral primary aldosteronism

ObjectiveThe clinical significance of immunohistochemistry (IHC) for unilateral primary aldosteronism (PA) has been unclear. Individualized follow-up of PA patients could be in sight. Long-term outcomes of patients, classified based on IHC, need further investigation. We aimed to assess long-term clinical outcomes for unilateral PA, classifying patients based on IHC. DesignA nationwide observational study, with up to 16 years follow-up, executed in 2007-2016 at Landspitali University Hospital, tertiary referral center. Patients were diagnosed and treated in line with the current guidelines. Haematoxylin and eosin (H & E) tissue slides were stained using CYP11B1 and -B2 antibodies. All cases were re-evaluated and classified according to the HISTALDO consensus. Outcomes were assessed using the PASO criteria. PatientsAll unilateral PA patients diagnosed in 2007-2016 in Iceland, 26 patients aged 28-73 years, who underwent adrenalectomy, were included. MeasurementsAldosterone, renin, and cortisol values, use and dosage of antihypertensives, potassium supplementation, blood pressure and serum potassium pre-intervention and throughout follow-up, and histopathology results post-adrenalectomy. ResultsFollowing IHC, an aldosterone-producing nodule was seen in 12 adrenals, an aldosterone-producing adenoma in 10 and multiple aldosterone-producing micronodules in four. IHC altered histopathology from previous H & E diagnosis in 23% (6/26) of the patients. In total, 81% (21/26) of the patients had partial clinical success. Eight percent (2/26) of the patients needed potassium supplementation during follow-up. In the classical group, the AVS results were more determinative with significantly higher lateralization index (median 10.1 vs. 5.3, p = .04) and more contralateral suppression (median nondominant ratio 0.4 vs. 1.0, p = .03). One out of five patients with complete clinical success at 12 months post-op had severe relapse later, the other four were normotensive without antihypertensives for up to 10 years. ConclusionsWe found IHC mandatory for accurate histopathologic diagnosis of PA. Our results support the importance of contralateral suppression when interpreting AVS results. Also, the study highlights the complicated assessment of clinical outcome and importance of aldosterone and renin measurements during follow-up.