Primary aldosteronism caused by unilateral adrenal hyperplasia: rethinking the accuracy of imaging studies.

A rare type of aldosteronism, known as unilateral adrenal hyperplasia (UAH), is difficult to diagnose, not only because it fails to conform to the typical common subtypes, but also because imaging results are unreliable. We report 2 Taiwanese patients with UAH. Case 1 was a 44-year-old man with 2 episodes of hypokalemic paralysis. Hypertension and suppressed plasma renin activity (PRA) with elevated plasma aldosterone concentration (PAC) were observed. Abdominal computed tomography (CT) and magnetic resonance imaging (MRI) showed a right adrenal mass, but adrenal scintigraphy revealed no definite laterality. The patient underwent a laparoscopic right adrenalectomy. Adrenal cortical hyperplasia was discovered from results of the histologic analysis. Case 2 was a 33-year-old woman referred for hypokalemia, hypertension, and a left adrenal mass found on a CT scan. However, MRI revealed normal adrenal glands. The adrenal vein sampling for PAC showed overproduction of PAC from the left adrenal gland. A laparoscopic left adrenalectomy was done. Pathology results revealed micronodular cortical hyperplasia with central hemorrhage. Blood pressure, plasma potassium, aldosterone, and renin activity levels returned to normal after operation in both cases. Both patients have been well for 3 years and 16 months, respectively, after surgery. We review the literature and discuss the limitations of imaging studies.

Perioperative hypertensive crisis in clinically silent pheochromocytomas: report of four cases.

Improvements in imaging have resulted in an increase in incidentally discovered adrenal tumors. The adrenal incidentalomas have been identified in at least 2%-3% of patients receiving abdominal computed tomography (CT), and pheochromocytomas are reported to occur in about 5.1%-23.0% of those patients. Only a few case reports of clinically silent pheochromocytomas have been published in the English literature. Herein we present 4 cases of pheochromocytomas as unforeseen adrenal masses on abdominal images. The characteristics of these tumors were that they (1) were noted to have no particular symptoms, (2) were confirmed biochemically and pathologically with immunophenotypic staining, (3) were benign in nature, and (4) produced apparent blood-pressure fluctuations during the operation. Three of these patients underwent a hypertensive crisis during surgery, and antihypertensives were applied transiently for blood pressure control. Two cases suffered from dramatic hypotension after the tumor had been excised, and intravenous fluid expanders and ephedrine were necessary to maintain adequate blood pressure. The above changes in blood pressure had no correlations with the size of the tumors. Although these tumors were clinically silent, they indeed were biologically active. Surgical resection of these tumors was indicated, and the risk of complications, such as hypertensive or hypotensive crises, may be no less than those of other typical tumors. Thus, such tumors should be managed with great caution.