Endosonographic imaging in primary hyperaldosteronism

Objective: After primary hyperaldosteronism (PA) is hormonally documented, the most important step is to differentiate between a disease that can be surgically cured (aldosterone-producing adenoma – APA) and other entities of PA, especially bilateral adrenal hyperplasia (BAH). Classical imaging of adrenal glands (computed tomography, magnetic resonance, adrenal scintigraphy) may miss small unilateral or bilateral lesions or give ambiguous results, though it is necessary to make the distinction by adrenal venous sampling (AVS). We evaluated retrospectively the value of endosonography in detecting adrenal tumors or adrenal hyperplasia.

Patients and Methods: In 19 patients with hormonally confirmed PA (10 males, 9 females, age range 32–74 years, median age 53) endosonography was performed using a Pentax FG 32UA endosonoscope with a longitudinal 7.5MHz sector array. Patients with APA were referred to surgery, offering histological prove. Endosonographic data were related to data obtained by other diagnostic procedures (CT, MRI, AVS) as far as they were available (the patient collective was very inhomogeneous – patients referred and followed after diagnosis by different colleagues).

Results: 14 patients with APA (max. diameter 8–34mm, 11 leftsided, 3 rightsided), all detected also by CT and/or MRI, 3 confirmed also by AVS. One patient had micronodular hyperplasia on the opposite side, not detected by both CT and MRI. For all patients except 2 pathological assessment is available. The endosonographic characteristics of APA are: hypoechogenity, homogenity or slightly heterogenity with hyperechoic parts, sharp delimitation by a capsule, tendency to hypervascularisation. Five patients had a BAH (isoechoic, micronodular, large adrenals), for one of them confirmed by AVS, not detected by MRI.

Conclusion: Endosonography as a useful tool in detecting small adrenal abnormalities can be very helpful in PA: excluding an adenoma and confirming the BAH it may allow to skip invasive diagnostic procedures as AVS. Further (prospective) studies are necessary to confirm this finding.